Tony Wu's Underwater Photography Blog » humpback whale

Dead Humpback Whale Calf

tony — Thu, 05 Jan 2012 09:11:22 +0000

Early on 2 January, a baby humpback whale washed up on the beach in Odawara, which is about 60km south of where I am in Japan.

Dead humpback whale calf on the beach in Odawara, Japan

Yesterday, I travelled to the site to meet friends from the scientific community, who were planning to perform an autopsy to try to ascertain the cause of death. As it turned out, the local authorities didn’t have the proper equipment available to handle the whale, so the autopsy had to be postponed for a few days.

Fortunately, it’s the middle of winter here, so the carcass will keep to some extent, but the laws of nature dictate that additional deterioration will occur by the time dissection takes place.

Also, the cetacean pathologists will be at a meeting outside of Japan by then, so unfortunately, the cause of death will probably never be known.

Researchers measuring deceased humpback whale calf

To the best of my knowledge, the animal was dead when it washed ashore.

Some patches of skin were missing, which is to be expected given the situation. There were some minor abrasions here and there as well, but nothing to suggest that injuries were the reason for the little humpback’s death.

All that we were really able to ascertain is that the baby was male, measuring 6.87m in length. It probably weighed one to one-and-a-half tonnes or so, though we didn’t have the equipment to confirm that.

Penis of dead humpback whale calf

Baleen of dead humpback whale calf

My friends told me that the whale was the smallest humpback ever to have been recorded in a beaching/ stranding in Japan. Most babies that have washed ashore here have been in the eight- to nine-metre range. This is the third such beaching of the 2011-2012 breeding/ calving season in these waters.

[Amendment: I misunderstood what my friends told me about the size of the calf. I've received the full list of recorded humpback whale calf strandings in Japan, and it is clear that this beached calf is the smallest to be recorded during the winter season. The other records for this time of year reflect body lengths of between eight and ten metres, which implies that they were older, perhaps yearlings. The actual smallest dead humpback whale calf record in Japan is 6.11m in Ibaraki prefecture, found on 24 June 2002. The second smallest is 6.60m in Oita prefecture, found on 19 May 2004. So this one becomes the third smallest on record, but the smallest during this time of year.]

I’ve literally seen hundreds of baby humpback whales, but this is the first dead one I’ve come across.

The size of the calf suggested to me that it was quite young, perhaps a couple/ few months at most. It appeared to be about the same size as the larger calves in Tonga attain by early September each season, which is about two to three months into the breeding/ calving season there.

Researchers hard at work collecting data

I arrived on location quite early, around 07:15, so there weren’t many people around and the light was still subdued. There was a brisk, bone-chilling breeze coming in from the sea. It took a few moments to collect myself when I saw the carcass.

Death, I suppose, is never a pleasant subject, but I’ve rarely had problems dealing with reality. In this instance however, I got a little choked up. I’m not ashamed to admit that I feel a particularly strong emotional bond with humpbacks, given the hundreds, perhaps thousands, of hours of my life I’ve devoted to them.

With light levels changing rapidly and the prospect of spectators showing up, I had to work quickly though, so I whipped out my cameras and commenced photographing. As soon as I started concentrating on handling problems like balancing white-out from harsh backlighting against the all-black of the whale’s body, the immediate shock of confronting the dead whale wore off.

Single hair follicle protruding from tubercle

The most interesting part of the experience for me was seeing a hair follicle protruding from one of the tubercles on the humpback’s rostrum. I knew in concept, of course, that each of these tubercles has a single hair inside, but it’s normally not possible to observe tubercles so closely.

When the researchers pointed the hair out to me, I think I let out what can only be termed a shriek of excitement.

I flopped belly-down on the rocks and got soaked by the incoming surf a couple of times while looking at and photographing the hair, but the cold seawater drenching was worth it.

That single hair was confirmation that what lay before me was a mammal, evolutionary kin in a way, though we look almost nothing alike and lead such different lives.

It’s tempting to wonder, even speculate, about what led to this animal’s death, but in reality, there’s just no way to be certain. Even with an immediate autopsy, the ability to ascertain the cause of death wouldn’t be assured.

All we can do is measure, record, learn what we can…and hope that there aren’t too many more.

Researcher examining the humpback whale calf

Happy New Year!

tony — Sat, 31 Dec 2011 23:34:17 +0000

“Welcome to 2012…”

“…see you underwater!”

Humpback Whale Singer Audio

tony — Sun, 18 Dec 2011 04:41:27 +0000

Locating humpback whale singers underwater is a challenge, but it’s fun. There’s nothing quite like tracking down a singer bit-by-bit, swimming along, scanning the water until the vague outline of a cetacean emerges from the misty blue haze.

Sound travels so well underwater that it’s extremely difficult to gauge direction and distance. Also, singers can stay down for extended periods of time, often diving too deep to see, sometimes swimming as they sing, sometimes sitting in plain sight but countershaded so well that you cruise right past them.

We found 14 singers this season, which is pretty high. Single-digit tallies are more common, not necessarily because there aren’t more singers around, but due in large part to the amount of time and effort it takes to track a singing whale down.

We came across the first singer of the season on 13 August, pictured below:

First humpback whale singer I came across in the 2011 season.
Note the lopsided fluke.

The water wasn’t clear (bad viz. characterised the season), but the whale wasn’t too deep, about 15m (around 50ft) or less at the fluke from what I remember. It stuck around long enough for everyone to get a good look, and for my friends Debbie and George to record some video. (Debbie actually recorded the video. It was enough for George just to stay out of the way.)

They just forwarded me the following audio tracks of the singer, which they extracted from the video footage (Thanks Debbie, George!).

It may not come across in these recordings, but it seemed like the bass this year wasn’t as deep and booming as normal. I hung directly overhead this one and several others this season, and I didn’t get the same intense reverberation in my body as I have in the past.

Here’s a video from the 2010 season showing what it’s like to make a short courtesy call to a singing humpback whale. This one was considerably deeper, 20-25m at the fluke.

Whales, Whales, Whales

tony — Wed, 07 Dec 2011 08:56:29 +0000

If you’ve been following my ramblings in recent months, it’s probably obvious that I’ve been spending an increasing proportion of my time with large cetaceans. My schedule for next year is no exception, with 12 to 13 weeks or so planned for ~~sitting on a boat staring at the ocean hoping something will show up~~ whale photography.

For those of you who are crazy enough to contemplate joining me on one of these adventures, I’ve set out basic trip descriptions below.

If you read on, you’ll no doubt notice that many of the trips are already booked. This is because I keep a list of people who contact me in advance, and I do my best to get in touch with anyone who’s expressed interest before announcing trips on my blog. I also send out an e-newsletter in advance of posting to this site.

If you’d like to get a heads-up for future trips, please contact me via my contact form, or sign up for my trip newsletter.

Please let me know if you’re interested, even if the itinerary you’re keen on is full, as I keep a wait list for each of the trips. Life happens sometimes, and people who’ve signed up end up needing to change their plans.

Blue Whales, Sperm Whales in Sri Lanka
Dates: March/ April 2012
Availability: Fully booked

This trip requires someone who is accustomed to less-than-ideal circumstances, can deal with frustration, and can accept the possibility of being totally and utterly skunked.

Sounds like fun, no?

To be a good fit for this adventure, you need to be very, very experienced in the water, be easy-going and cooperative, and have a stable, mature personality.

On the upside, there is the prospect of seeing scenes like the images below, as well as other potential surprises:

Sperm whale swimming upside-down to check me out with sonar

Blue whales(!) swimming in blue water

Minke Whales in Australia
Dates: 28 June to 7 July
Availability: One spot available
Location: Fly into/ out of Cairns, transfer to Port Douglas
Accommodation: Liveaboard trip

Minke whales have been on my to-do list for a long time. As far as baleen whales go, they’re relatively small, running six to ten metres in length. They’re inquisitive…as in, they’ll come right up to boats and people in the water given the right mood. They’re also reasonably easy to find…if you get the timing and location right.

For these reasons, I’ve planned a trip Down Under to spend some quality time with the minkes that congregate at the Great Barrier Reef.

We’re heading over during absolute peak minke whale season.

The plan is to get on a boat in Port Douglas on 28 June, cruise overnight to minke central and sit there until we leave on 6 July to head back. That’s eight full days with minkes, only minkes, and just minkes.

We’ll be in the Great Barrier Reef Marine Park, so we’ll be following the well-established guidelines for in-water interactions with the small cetaceans, letting the whales dictate the pace and proximity of interactions.

I specifically picked the timing for this trip based on advice from my friends John Rumney, who is one of the leading authorities on minkes Down Under, and Julia Sumerling, who has many years of minke experience under her belt from working as the video/ photo pro on Mike Ball’s boat.

To cut to the chase, our trip will be during peak, peak minke time.

For whatever reason, the minkes show up like clockwork at this time, and more importantly, they demonstrate the greatest level of interest in people around this period.

Incidentally, the minkes in this area are a subspecies known as dwarf minke whales, which were first described in 1986. From what I gather, there is still no population estimate for this subspecies, and no consensus on the taxonomy for minke whales in general.

For more information about the dwarf minkes, please see the excellent summary prepared by the CRC Reef Research Centre (PDF file).

Minkes are inquisitive, and some will approach really close.

Humpbacks Whales in Alaska
Dates: 22 to 31 July
Availability: Fully booked
Location: Trip begins and ends at Juneau, Alaska
Accommodation: Liveaboard

This is the Megaptera Mania! trip I’m running with Jon Cornforth.

I’m really excited about heading to Alaska for the first time. I’m not so keen on the fact that it’ll be colder than I normally like, but bubble-net feeding and dramatic, mountainous terrain in the background will hopefully make it worthwhile, and also worth a repeat visit in 2013.

Humpback whales bubble-feeding at sunset in Alaska

Humpback whale breaching in Alaska

Humpback Whales in Tonga
As soon as we wrap up in Alaska, I’ll be heading over to Tonga for my annual stay, and to continue my calf count project. After the record number of baby whales I ID-ed this year, I can’t wait to see what happens in 2012!

My schedule for Tonga is still evolving, but here’s how it looks at this time:

Trip 1: 21 to 28 August. This is the second part of the Megaptera Mania! trip. Fully booked.
Trip 2: 29 August to 06 September. Two spots available.
Trip 3: 08 to 17 September. Fully booked.
Trip 4: 25 September to 3 October. Four spots available.

Tahafa, calf #14 of the 2011 season, with mommy

Fluke of a humpback whale singer

Season’s Greetings…almost

tony — Sat, 03 Dec 2011 13:07:25 +0000

A confluence of circumstances has kept me from posting anything since I hunkered down and cranked out my calf count summary at the end of October.

I’ve answered approximately three million emails (give or take a handful); I’ve caught up on current events (given the way things are going, I kinda wish I hadn’t); I’ve finally rid my site of hacks that were doing all sorts of funky things (in the worst possible connotation of the word funky); I’ve had a bunch of meetings (both physical and virtual); I’ve helped judge a photo contest; I’ve hit the gym and gotten back into decent shape; I’ve organised most of my trips for next year; I’ve read a pile of research papers about cetaceans and other marine life; I’ve managed to sleep at least a few hours a night; and I’ve even gotten some work done. Whew.

By way of proof that I’ve actually been working, here is a video of sperm whales that Smithsonian Magazine posted recently to complement an article about these amazing animals in the December 2011 issue, titled Call of the Leviathan:

The footage is from recent trips I took to Dominica and Ogasawara to photograph sperm whales. I can’t take credit for the excellent editing though. Brendan, the photo editor at Smithsonian Magazine, did a bang-up job of making my footage look decent. (Thank you Brendan!)

And this is a link to an interview I did with Radio Australia recently about the humpback whales in Tonga. It’s short, but important.

Here’s the audio in case you can’t access the link:

There were suggestions by another person in an earlier interview that humpback whales use their pectoral fins to stroke swimmers in the water, sometimes even lifting swimmers en masse into the air out of exuberance. Poppycock.

I’m the first to admit that being in the water with humpbacks can be a magical, almost mystical, experience, but there’s no good that can come of people visiting Tonga and expecting to be stroked by whales. None whatsoever.

Bruce Hill, the presenter of Radio Australia’s Pacific Beat program, was kind enough to give me an opportunity to set more realistic, and safe, expectations for anyone who might be contemplating a trip to Tonga. (Thanks Bruce!)

Anyway, I’m back at the helm, and I’ll be posting more from now on, including information about upcoming trips.

To get back into the swing of things, here is one of my favourite humpback whale fluke photos. It was a stormy day back in 2005, and it’s the only time I’ve ever seen two adult humpbacks tandem tail-slapping. Their slaps weren’t in sync, plus the seas were rocky, so it took quite a few tries to nail the right timing and composition.

Humpback whales tandem tail-slapping in Tonga

48 Baby Humpback Whales!

tony — Sun, 30 Oct 2011 12:00:14 +0000

48! That’s right…four dozen!!!

That’s the record-breaking number of humpback whale babies that I’ve ID-ed and catalogued since getting back from Tonga several weeks ago.

To put that into some context…that’s 2x the number of babies we counted in 2010.

Moreover, our previous record was 31 mother/ calf pairs (in 2009), meaning that we blew past the high tally two seasons ago by 17! Or to look at it another way, this year’s count trounced the previous high by a factor of more than 1.5x!

In case it’s not entirely obvious, I’m really excited. Like, giddy-little-kid-who-scarfed-down-too-much-halloween-candy excited.

First, because having so many baby whales is obviously terrific news for the ongoing recovery of the southern hemisphere humpback whale population. And second, because it’s vindication.

Back in the day, when I first started visiting Vava’u, the generally accepted wisdom was that there were perhaps a half dozen babies, maybe a few more, that were seen in the area each season. Within short order, I started to believe that there were more. Many more.

In fact, back in 2004, I went out on the proverbial limb (where I have tendency to find myself) and said there might be 40 or more babies in a season.

It’s taken a number of years, but this season’s calf count finally proves that 40 to 50 baby humpback whales in the Vava’u area is not only do-able, but is almost certainly an underestimate in some seasons.

Although I’ve photo-identified 48 mother/ calf pairs, there were many more whales that I either didn’t see, or did see but wasn’t able to ID. In fact, I have a number of photos of mother/ calf pairs that I think are additional ones. The thing is…I can’t be 100% sure, so I haven’t included them. Bummer, but all-in-all, it’s better to be conservative than to incorporate questionable data.

Summary of humpback whale calf sightings in Tonga during the 2011 season

One thing that I want to make clear…even though I’ve put in the time to organise, sort through and compile the data, there are actually a lot of people involved in this effort.

To name but a few: The many people who joined me in Tonga (62 people this season, hundreds more in the past!), who in effect, funded the time to undertake this project; Friends who’ve contributed photos and IDs this season, like Shawn, Douglas, Allan and Ma’ata; Friends like Mark and Karen, who sent me valuable information to help piece together theories about false killer whale attacks and escort relationships; The boat captains and crews (Endangered Encounters, Whale Watch Vava’u), whose dedication to keeping us safe and happy was invaluable; and Takaji and Emiko, who’ve been working with me on this project since we started.

In other words, this project is a group effort, involving dozens of people from all around the world. Thank you very much!!!

Given the high number of whales, the full summary is big. It’s a 64-page PDF file and about 196MB. To make this information as accessible as possible, I’ve prepared two different files available for download. The first is the 15-page summary, which is an overview of the key points but does not contain any of the photo-ID sheets. It is a 3.4MB file.

The second is the full 64-page document, which contains the 15-page summary plus photo-ID sheets for every ID-ed calf. It is 196MB.

Right click on the relevant link below to download the files.

Humpback Whale Calf Encounters in Tonga 2011 – Summary Only (v1, 31 October 2011)
~~Humpback Whale Calf Encounters in Tonga 2011 – Full File (v1, 31 October 2011)~~
Humpback Whale Calf Encounters in Tonga 2011 – Full File (v2, 01 November 2011, updated 201142 Faua to show split dorsal fin. Thanks to Robert Pierce for pointing out the split fin!)

In addition, I’ve uploaded all the location data for our calf sightings to two Google Maps. The first is this one, which shows the locations of all of our encounters with humpback whale mother/ calf pairs that I was able to ID:

View 2011 Humpback Whale Calf IDs Tonga in a larger map

The flags represent GPS data; the blue dots are hand-marked locations. I encourage you to click through to the full map, as there are notes for each of the encounters, and it’s much easier to view the information on the full map.

The second is a map that shows the locations of mother/ calf pairs that we encountered, but were unable to establish IDs for. The red pins are mother/ calf pairs I wasn’t able to ID; the green pins are mother/ calf pairs initially marked as unknowns, but later assigned IDs after reviewing photographs. Again, if you click through to the full map, there are notes for each of the sightings.

View 2011 Unidentified Humpback Whale Calf IDs Tonga in a larger map

Finally, in case you have a bad connection and can’t download either file, I’m appending the text of the summary to the end of this post. I can’t, however, include the four summary tables, which set out all the encounters and timelines. The only way to view those is to download one of the two files.

One request: If you have photographs and sighting information for humpback whale mother/ calf pairs from this season that are not in my summary file, please let me know. It would be just so awesome to cross the 50-calf mark!

I will post updated versions of my calf count file as and when additional data comes in.

Here’s the introductory text of my humpback calf count summary for the 2011 season in Vava’u, Kingdom of Tonga:

Introduction
This document is a summary of humpback whale calf encounters in and around the Vava’u island group in the Kingdom of Tonga during the months of August to October 2011.

During our stay this year (05 August to 01 October), we identified 45 humpback whale mother/ calf pairs over the course of 73 in-water encounters, with three additional IDs contributed by friends, for a total of 48 humpback whale mother/ calf pairs.

We initially recorded 33 sightings of calfs that we were unable to identify at the time of encounter. We were later able to assign IDs to two of those 33 in the process of preparing this summary, lowering the total unknown calf sightings to 31.

This is the highest number of mother/ calf pairs we have identified and tabulated since commencing this annual calf count project in 2008.

This season was notable in other respects as well:

There were reliable reports of whales arriving in the Vava’u area by mid-June, with calf sightings reported before the end of June. This is several weeks earlier than the timing in a hypothetical average season, and contrasts with the relatively late arrival of the whales in 2010. The whales did not, however, seem to leave the area any earlier than normal.

Overall whale behaviour/ disposition was “neutral”, meaning significantly less standoffish than in 2010, but not as approachable as in “friendly” seasons like 2009.

We documented three returning mothers. The mother of 201132 Toluua was also the mother of 200913 Luna, easily recognisable by her unique dorsal fin. Of note, her relaxed disposition was the same as it was two years ago, and both juveniles were friendly and inquisitive. The mother of 201107 Fitu was the same as the mother of 200920 Mama’s Boy. And the mother of 201115 Tahanima was the same as the mother of 200814 Jet.

We documented three mother/ calf pairs travelling between Vava’u and Toku Island, about 40km away. Travel among islands is not unusual, but it is the first time we have documented this taking place with photographs and GPS data.

For the first time, we recorded data pertaining to escort relationships with mother/ calf pairs. Over half of all mother/ calf pair encounters involved at least one escort, which seems to be a relatively high ratio viz. other humpback whale breeding and calving grounds.

We documented two long-term associations between an escort and mother/ calf pair: At least 14 days for 201114 Tahafa and at least 18 days for 201142 Faua. This is the first time we have observed/ noticed this. Such long-term associations seem to be unusual, or perhaps not well documented.

Of interest, in both cases of long-term escort association, the mother/ calf pairs undertook the 40km journey between Vava’u and Toku while in the company of their respective long-term escorts.

We also documented three occasions when escorts with mother/ calf pairs were singing, or vocalising in a song-like manner: 201114 Tahafa, 201121 Uataha and 201130 Tolunoa. We have come across this behaviour on multiple occasions in previous seasons as well.

There were two juveniles with all-white pectoral fins, the first we’ve seen in the Vava’u area. They were 201127 Uafitu and 201142 Faua.

We documented several juvenile whales with injuries that suggest coordinated attack by a pod of marine mammals, possibly false killer whales (Pseudorca crassidens).

Overall, there was an abundance of whales this season, a lot of interesting social interaction, and many opportunities to observe and record humpback whale behaviour. This document focuses upon the mother/ calf pairs and associated whales. For additional background information, please refer to the following blog posts:

Swimming with Humpback Whales in Tonga | 2011 Season Part 1
 Swimming with Humpback Whales in Tonga | 2011 Season Part 2 
Swimming with Humpback Whales in Tonga | 2011 Season Part 3 
Swimming with Humpback Whales in Tonga | 2011 Season Part 4 
Swimming with Humpback Whales in Tonga | 2011 Season Part 5 
Swimming with Humpback Whales in Tonga | 2011 Season Part 6 
Swimming with Humpback Whales in Tonga | 2011 Season Part 7
Swimming with Humpback Whales in Tonga | 2011 Season Part 8

All of this work has been and is being done on our own time, with our own resources. We are not receiving financial or other assistance, and we are not affiliated with any person or organisation involved with cetaceans.

If you have photographs of humpback whale mother/ calf pairs from the 2011 season in Vava’u that are not included in this file, or additional information about whales already included in this document, please contact Tony Wu.

Reference documents:
2008 Calf Summary, 2009 Calf Summary, 2010 Calf Summary

Methodology

Our basic methodology has remained unchanged since commencing this calf count project, with our core ID team comprising Tony Wu, Takaji Ochi, and Emiko Miyazaki.

We recorded GPS locations for all sightings of humpback whale calfs upon initial visual and/ or radio confirmation. We used Garmin GPS 60 and GPS 72H handheld units for marking GPS locations and converted to Google KML format using HoudahGPS. When GPS units were not available, we marked locations by hand on a map.

Where possible, we entered the water to photograph mother/ calf pairs and other associated whales if any.

We made notes of behaviour, easily recognisable physical traits, and any other noteworthy circumstances.

For the first time, we have recorded the number of escorts with each mother/ calf pair sighting, for the purpose of tracking escort activity from this season onward.

When we were able to take photographs of sufficient quality and quantity to establish an ID, we named and assigned a numerical ID to the relevant calf.

In those cases where we were unable to get sufficient photographs to establish ID, we did not name the calfs. We recorded the sightings as unknowns and cross-checked any photos of such juveniles with subsequent ID-ed whales to look for possible matches.

We have uploaded all the GPS and hand-marked location data to Google Maps, where the locations of all ID-ed calfs and unidentified calfs are available for viewing. GPS locations are also embedded as hyperlinks throughout this document when there is text that refers to date and location of sightings. Clicking the hyperlinks will take you to Google Maps to view the relevant location.

The photographs contained in this document represent a small portion of the images we collected. For most ID-ed calfs, we have many more images for verification purposes.

Observations

Figure 1 below illustrates our cumulative calf counts over the past four seasons (incorporating all ID-ed juvenile whales each season, including those contributed by third parties). While we recognise that there are inherent differences in each season (different periods of stay, varying number of boat days, weather variations, etc.), the slope of the line representing cumulative calf count has appeared relatively similar across previous seasons. With the addition of data for 2011 however, a divergence in the slopes of the curves for 2009 and 2011 from those for 2008 and 2010 is apparent. This makes intuitive sense against the backdrop of the number of calf encounters, overall whale mood and other conditions in each season.

Cumulative count of humpback whale calf IDs in Tonga

During our stay this season, we had 73 encounters with 45 mother/ calf pairs that we identified over 76 boat-days on the water (compared with 22 calf IDs over 81 boat days in 2010; 26 calf IDs over 59 boat days in 2009; 16 calf IDs over 67 boat days in 2008; 14 calf IDs over 53 boat days in 2007). This worked out to 0.59 Calf/ Boat-day, with a boat-day being defined as a single day of approximately six hours on the water on a boat looking for whales. These figures do not include calf IDs contributed by other people.

Humpback whale calf IDs per boat day in Tonga

As is apparent from Figure 2, this season was exceptional, with the Calf/ Boat-day ratio significantly exceeding the levels recorded in each of the previous seasons. In our 2010 summary, we posited that a Calf/ Boat-day ratio of 0.25 might represent the norm, with 2009 being an outlier. With this season’s ratio of 0.59 however, the question of whether there is a normal level or not becomes more intriguing.

It is certainly possible that our experience in 2011 is exceptional, and that we will not see a similarly high number and density of humpback whale mother/ calf pairs in the Vava’u area in the future. However, given the 0.44 ratio recorded in 2009, and our personal recollections of similarly high numbers and frequency of mother/ calf pair encounters in 2004 and 2005, it seems possible that there is no “norm”, and that the Calf/ Boat-day figure may vary unpredictably within a relatively broad band.

What this underscores is that extrapolating from limited observation in any single season to draw conclusions about the dynamics of the southern hemisphere humpback whale population is inadvisable. Only long-term observation and consistent recording of data may eventually reveal underlying patterns and trends.

In addition to the calf IDs we established, we received three more mother/ calf pair IDs from friends (201115 Tahanima from Shawn; 201143 Fatolu from Douglas, 201148 Favalu from Allan/ Ma’ata), bringing the total ID-ed calf count to 48.

In 2009, we commenced recording sightings of unknown mother/ calf pairs (those whales which we are unable to ID at the time), by marking GPS location, taking notes about behaviour, and taking photos when possible, for the purpose of trying to establish IDs at a later point. This year, we recorded 33 unknown mother/ calf pairs. We were later able to establish IDs for two of those 33 (Unknown calf #10 = 201146 Faono; Unknown calf #27 = 201147 Fafitu), meaning that we ended up with 31 unidentified calfs (compared with 16 in 2010; 24 in 2009).

Figure 3 depicts the total Calf Sighting Ratio for 2009 to 2011, where we have defined Calf Sighting Ratio as = (Total ID-ed calf count + Total unidentified calf count)/ Total boat-days. This ratio was 1.01, which compares with 0.49 for 2010 and 0.85 for 2009. This ratio provides a reasonable indication of the overall level of humpback whale mother/ calf pair activity in the Vava’u area.

Calf Sighting Ratio for 2011 Humpback Whale Season in Tonga

We again found mother/ calf pairs throughout the entire topography of the Vava’u Island group without apparent clustering or preference for a specific area. As with 2010, however, there were not many sightings in North Bay, once again consistent with our experience from most previous seasons. 2009 was the exception, when we recorded a significant number of encounters in North Bay. We recorded more encounters in the Toku area than in previous seasons. This may, however, have been due to the fact that calm conditions prevailed for a number of days in the latter part of the season, allowing several visits to Toku. See map of ID-ed mother/ calf pairs and map of encounters with unidentified whales.

The pattern of sightings once again supports our notion that, for the most part, humpback whale mother/ calf pairs use Vava’u as a transit area, visiting for a short duration before moving on, returning to the area at a later date in some instances. Within this context however, we have documented a number of repeat sightings over extended periods of time:

201103 Tolu (4 encounters/ 30 days);
201114 Tahafa (9 encounters/ 33 days, Vava’u to Toku to Vava’u);
201120 Uanoa (3 encounters/ 27 days);
201123 Uatolu (2 encounters/ 29 days, Toku to Vava’u);
201130 Tolunoa (2 encounters/ 33 days); and
201142 Faua (2 encounters/ 18 days, Toku to Vava’u).

This adds to our long-term repeat sightings in previous seasons:

201005 Ikumi (11 encounters/ 31 days);
201008 Lele (3 encounters/ 11 days);
200904 Stitches (4 encounters/ 23 days); and
200912 Luna (3 encounters/ 13 days).

Of note is that in three of the long-term sightings for 2011, the relevant mother/ calf pairs were sighted in both Vava’u and Toku. This is the first time we have documented travel by mother/ calf pairs between the two locations, which are about 40km apart.

As was the case in 2009 and 2010, the ratio of female to male juveniles favoured females. This year, we counted 13 females and 10 males. In 2010, it was 7 female to 4 male. In 2009, it was 14 female to 9 male. Given that this relationship has remained in favour of females for three consecutive seasons, it’s tempting to speculate that females may represent a greater proportion of overall calf births than males. Since it is not possible to establish the sex of every juvenile encountered, we cannot be certain of this however, and need to consider other possible explanations as well. It could be the case, for instance, that mother/ calf pairs with female babies tend to be more favourably disposed to interacting with people.

Ratio of female to male humpback whale calfs in Tonga

We documented long-term escort relationships with two of the mother/ calf pairs sighted over an extended period of time. In the case of 201114 Tahafa, the same escort stayed with the mother/ calf pair from at least 01 September to 14 September (14 days). In the case of 201142 Faua, the same escort remained with mother and calf from at least 20 September to 07 October (18 days). To the best of our knowledge, such long-term escort + mother/ calf relationships have not been documented previously in this area.

Spurred in part by observation of these long-term escort + mother/ calf relationships, we commenced recording escort sightings this season. In several instances, we were able to observe the effects of escorts on mother/ calf behaviour. In some cases, the adult females appeared to dislike the attention of the males; in other cases, the presence of an escort seemed to have a calming effect. We have made notes of such behaviour in the individual ID pages that follow.

Out of 48 ID-ed mother/ calf pairs, 30 were accompanied by escorts in at least one encounter with the relevant mother/ calf pair, a ratio of 0.63. Out of 76 total encounters with those 48 ID-ed mother/ calf pairs, 40 encounters involved at least one escort, a ratio of 0.53. In the case of unidentified mother/ calf pairs, the ratio was 0.35. We only calculated one ratio for unidentified mother/ calf pairs because we had only one encounter with each pair. In any event, the proportion of mother/ calf pairs accompanied by escorts was high. Subjectively, this is consistent with our experience in previous seasons.

Frequency of escort whales accompanying mother/ calf pairs in Tonga

We documented three repeat mothers this season, making a total of five females that we’ve documented returning to the Vava’u area with second babies since 2008.

The mother of 201132 Toluua was the same as the mother of 200913 Luna. Her unique dorsal fin made it easy to recognise her, and her overall friendly disposition in both 2009 and 2011 made it relatively easy to photograph her and the calf. Of note, both Toluua and Luna were inquisitive and pro-active in their approach to people in the water.
The mother of 201107 Fitu was the same as the mother of 200920 Mama’s Boy.
The mother of 201115 Tahanima was the same as the mother of 200814 Jet.

Female humpback whales that we’ve documented
returning to Vava’u with a second baby

We documented several juvenile whales with injuries that suggest coordinated attack by a pod of marine mammals, possibly false killer whales (Pseudorca crassidens). Refer to summary pages for 201107 Fitu, 201114 Tahafa, 201120 Uanoa, and 201144 Fafa to see the wounds. See also this blog post for a discussion of this topic.

We documented two juveniles with all-white pectoral fins: 201127 Uafitu and 201142 Faua. This is interesting because these are the first such calfs we have seen in the Vava’u area. In previous seasons, we had wondered where the adults with all-white pectoral fins come from, as we had not seen any juveniles with this trait.

Just For Fun

tony — Mon, 24 Oct 2011 06:45:18 +0000

In the process of going through many GBs of data to put together my humpback whale calf count summary, I came across the image below.

School of barracuda with humpback whale mother and calf in the background. Seriously?!!!

It’s certainly not the best photo I’ve ever taken, but hey…how many times do you get to snorkel down to a decent-sized school of barracuda and take a snapshot with a humpback whale mom and baby in the background?!

It would’ve been more effective if the barracuda had been cooperative enough to heed my pleas to: “Turn sideways!”, but the fish were, for whatever reason, horizontally challenged.

Incidentally, I’ve made it through the 45 mother/ calf pairs I ID-ed while in Tonga, and confirmed that I didn’t double-count any of them.

Even better, after careful review of the images, I think I may have two or three more to add to the tally.

If all goes well, I’ll post the summary file and accompanying maps in the next day or two.

2011 Humpback Whale Season in Tonga: Part 8

tony — Sun, 09 Oct 2011 08:45:15 +0000

It’s been a while since I’ve had a chance to post. Things got a little hectic toward the end of my stay in Tonga, and my re-entry into urban life has been as chaotic as usual. But I’ve finally settled back into (some semblance of) a normal routine, and I’m hard at work catching up on my to-do ~~list~~ mountain.

Final Calf Encounter
Before departing Tonga, I was fortunate enough to have one last encounter, with a humpback whale calf that I had not come across before…Fanima (female), the 45th(!!!) calf of the season.

Fanima was a big baby when I met her. I estimate that the mini-Megaptera was close to half the length of her mother, which suggests that she was born early in the season.

Perhaps in part because the calf was relatively mature, mom was laid back. She seemed, in fact, almost entirely unconcerned with what the little one got up to. Fanima played and splashed at the surface with considerable vigour, executed many a whimsical twirl, checked the boat out on multiple occasions, and peered with intense curiosity at anyone in the water.

Fanima (calf #45) was my final calf encounter for the 2011 season.
Given her relatively large size, Fanima was probably born early in the season.

We did, however, have a bit of drama.

Before I had a chance to take any photos, an escort appeared without warning out of the deep, surging up beneath Fanima’s resting mother, waking the female from her slumber. Not surprisingly, Fanima’s mom bolted, with calf in tow. Females of any species…as it turns out…don’t enjoy being taken by surprise.

When escorts approach suddenly like this, relaxed mother/ calf pairs often take off and swim at high speed for considerable distances.

I was alone in the water at the time, and groaned in despair at the prospect of having lost the opportunity to ID the calf.

Fortunately, mother and baby settled again after only a few minutes. Mommy, it seems, decided that she liked the escort and let him stay. Whew! I’ve seen this happen before, but less often than I’ve seen the swim-swim-swim-away scenario play out.

With that, we spent a wonderful hour or so cavorting with Fanima, mother and escort…a perfect way to wrap-up an incredible season of humpback whale encounters.

Humpback whale calf Fanima having fun swimming upside-down

Incredible Season
2011 was my tenth humpback whale season in Tonga, my ninth consecutive one.

It was also the most amazing. I think I learned more about humpback whale behaviour over the past two months than I have in all the other seasons combined!

The relatively high number of whales this season was certainly a big factor. After all, the more whales there are, the more there is to see.

But I think the cumulative weight of previous experience may have tipped the scales as well. Bits and pieces from seasons past seemed to fall into place, affording me a glimpse of the bigger picture…like the moment when a jigsaw puzzle finally coalesces.

I’m still processing everything I experienced and learned this season, but here are some key points that come to mind:

Record number of baby whales: To date, I’ve ID-ed 45 humpback whale mother/ calf pairs. My previous record was 31 mother/ calf pairs in 2009, set out in this file: humpback whale calf count file for 2009.

I have to double-check the IDs to make sure I didn’t double count, but I have a reasonably high degree of confidence in this tally, given the many(!) hours I’ve invested squinting at the finer details of whale body patterns, dorsal fins, flukes and other markings. Of course, I’m hoping to receive additional data that will increase the final count, but in any event, I’m 100% certain that there were many more babies in the area.

Record-breaking mother was a repeat from 2009: The mother that broke the previous high count of 31 was a female that I had previously ID-ed with a calf in 2009. The female in question was the mother of Luna (calf #13, female, in 2009) and returned this season with Toluua (calf #32, female). I recognised the mom on sight because of her unique dorsal fin, but also…more interestingly…because of her personality/ disposition. See Part 5 for a discussion of this inspiring encounter.

This is now the third female I’ve documented returning with a second calf. There might be more repeat mothers in this year’s crop. I just haven’t had time to do a methodical comparison yet.

Worst visibility ever: The underwater visibility this season was consistently the most mucked-up and worst that I’ve experienced to date. There have, of course, been periods of poor visibility before, but the less-than-ideal conditions persisted for the entire season. Visibility was poor far offshore as well, in areas that would be clear under more normal circumstances.

I have no idea what caused this prolonged phenomenon. I’m guessing it’s a lingering effect of the prolonged El Niño/ La Niña cycle that finally ended a while ago, but really…who knows?

Earliest whales ever: Somewhat offsetting the bad visibility was the fact that the whales showed up as early as I can recall. I wasn’t in Tonga at the time, but I received reliable reports of whale sightings in June, with the first babies spotted in late June. To put that in perspective, I usually expect the earliest humpback whale calfs to be spotted in mid- to late-July or so.

You might recall that the whales showed up relatively late last year, so this marks a stark contrast between the two consecutive seasons.

One thing I’ve been keen to see is whether the whales leave Tonga earlier than usual as a result of their early arrival in the area. We’re a third of the way through October now, and while the number of whales has declined, it seems like there are still quite a few around, as one would expect at this stage in a “normal” season. I’ve received several reports of excellent in-water encounters over the past few days.

Toluua (calf #32), who’s mom is the same as the mother of Luna, calf #13 of 2009!

Lots of whales as well: Going hand-in-hand with the early arrival of the whales was the seemingly high number of humpbacks.

Last season, it seemed as if there weren’t as many whales around as in a given “average” season. This year, there were certainly some days when there were few whales to be found, but in general, an abundance of whales characterised the season.

Go figure…Escorts are actually interesting: I’ve always considered escort whales that associate with mother/ calf pairs a bit of a nuisance. They often “push” the female/ baby whales and make them swim at high speed for prolonged periods, making it difficult to get a look in the water, much less take photos.

But I started noticing a few things about the escorts this season.

For instance, in Part 3 of my updates, I documented one escort hounding two separate mother/ calf pairs (calf #17 Tahafita and calf #18 Tahavalu) on consecutive days, with both mother/ calf pairs seemingly doing their best to get away from the pesky male in question. I named him “Two-timer”.

Two-timer’s plight was a clear contrast to the way that the presence of an escort seemed to settle Tolu’s (calf #3, male) mom, as I described in Part 2, and also to the way that Tahafa’s (calf #14, male) mom seemed to take comfort in the presence of her long-term escort, as I set out in Part 5. Recall also from the write-up about Fanima (calf #45, female) above, that Fanima’s mom only took a few minutes to accept the presence of the escort.

Perhaps this is obvious, but it seems that female humpbacks are receptive to overtures from some males, but not others.

I’ve also seen this behaviour among sperm whales, where females seem to “like” or “not like” individual adult males, so perhaps this is a universal phenomenon? (For my own good, I’ll resist the temptation to draw any parallels to human female behaviour, however obvious.)

Escort relationships can be long term: I had always assumed that escort relationships with mother/ calf pairs were relatively short term. Actually, to be more accurate, I hadn’t given the topic much thought, as ID-ing mother/ calf pairs was my priority, and escorts were just sort of “in the way”.

This season, I’ve documented two relatively long-term relationships between an escort and a mother/ calf pair.

The first involved Tahafa (calf #14, male), with a single escort staying with the mother/ calf pair for a period of at least 14 days (1 to 14 September), as I described in Part 6. The second was Faua (calf #42, female), with a single escort present from 20 September to 7 October, a span of 18 days (just received photo documentation of this latest sighting).

My understanding from communicating with researcher friends in Hawaii is that no one else seems to have documented such long-term associations between an escort and a mother/ calf pair before. (If you know of any such documentation, please clue me in!)

Perhaps this is a phenomenon unique to the whales that frequent Tonga; perhaps it’s a fluke (excuse the horrible pun); or perhaps this happens elsewhere as well, but hasn’t been documented because it’s difficult to follow a particular escort + mother/ calf for an extended period.

Of additional interest, both of these escort + mother/ calf groups travelled the 40km distance between Vava’u and Toku. Maybe having an escort around is something mothers prefer when crossing open ocean? (See discussion of Pseudorca attacks below.)

In any event, picking up on these fascinating escort/ mother/ calf dynamics has sparked my interest in escorts, and from this season forward, I’ll be keeping records of the number of escorts we see with mother/ calf pairs, as well as taking careful notes on their behaviour, and photographing them more carefully for ID purposes (just what I need…more self-imposed work!).

Tahafa (calf #14), the undisputed star of the season

Singing escorts: One other escort behaviour that has me scratching my head is singing. Most people associate singing behaviour with lone males, hanging in the blue, belting out their haunting melodies. Males can also sing while they swim. In fact, “travelling singers” seem to be nearly as common as stationary ones, at least in Tonga.

But over the years, we’ve also come across a number of males singing when they’re with mother/ calf pairs. Again, I haven’t kept meticulous records of this, but in general, this seems to take place when more than one male is involved. It can sometimes be when the whales are resting, and at other times, when the whales are swimming.

We had two such observations this season. The first was with Uataha (calf #21). Two males approached the mother/ calf pair; there was a bit of commotion; and then there was an escort with the mother and calf…singing. The whales settled in shallow water, not moving much.

The second instance involved Tahafa (calf #14, male). In this case, there were multiple males challenging the primary escort repeatedly over the course of many hours. Amid the chaos and pandemonium, at least one of the males was singing…really loud! I think it was the primary, long-term escort, but I can’t be certain. There was a lot of action, and the whales definitely weren’t settled.

What does this mean? I’m not sure, but I do know that humpback whale singing behaviour is much more complex and nuanced than a lone male crooning while hanging head-down in the water.

Escort ratio is high: One final note about escorts…the ratio of mother/ calf pairs with at least one escort present is high in Tonga. This season, out of a given 10 mother/ calf pair encounters, somewhere between 4 and 5 will have had an escort or more (I’ll have a precise figure after I review all the data). My understanding is that such a high prevalence of escorts with mother/ calf pairs is unusual.

If you think about it, escorts should prefer single females over ones with babies, on the assumption that escorts are males looking to mate.

From memory, the ratio has always been high in Tonga, but again, I haven’t kept careful records to date. I did keep careful records this year though, so when I produce my calf count summary for this season, it will include a breakdown of escort relationships as well.

2011 Humpback Whale Season in Tonga: Part 7

tony — Sun, 25 Sep 2011 02:20:17 +0000

It’s been another eventful and educational week.

My calf count is up to 44 ID-ed mother/ calf pairs now (with several uncertain pairs to which I may be able to assign IDs after more careful review).

The new calf IDs this week comprised:
- Fataha (#41), accompanied by an escort;
- Faua (#42, male), the second calf with all-white pectoral fins that we’ve photographed this season. Mom also had all-white pectoral fins. This pair were also in the company of an escort;
- Fatolu (#43, female), ID contributed by my friend Douglas Seifert (who has been here with his lovely wife Emily for the past couple of weeks and has been kind enough to contribute valuable calf-sighting information and photographs…thank you!). No escort with this pair;
- Fafa (#44, female), another injured calf with wounds similar to those of Tahafa (#14, male). No accompanying escort.

Faua (#42, male), the second humpback whale calf with all-white
pectoral fins this season. Mommy also has white pectoral fins.

Resightings included:
- Uatolu (#23, female), which I originally ID-ed at Toku Island on 02 September, and Douglas Seifert photographed in Vava’u on 20 September (19-day interval). This is the second example we have documented this season of a mother and calf travelling between the two locations;
- Uanoa (#20, male), accompanied by an escort. We originally ID-ed this calf on 29 August. I subsequently received a photo of this calf from Kristy Peacock, a guest at Mounu Island Resort, taken on 24 August. I photographed this calf again on 24 September (an interval of 32 days from first documented sighting) and was able to determine that the calf is male;
- Tahafa (#14, male), our ninth(!) encounter with this injured calf. We have now documented this calf going from Vava’u to Toku then back to Vava’u, between 23 August to 24 September, a span of 33 days. For a detailed timeline of the first eight encounters, please see Part 6.

Overall, it seems that there are still many whales in the area, including mother/ calf pairs. We have, however, ID-ed fewer new calfs this past week than in previous equivalent periods. This could be due to chance, but I have a feeling that the lower tally may reflect the fact that we’re approaching the tail-end of the season, with an accompanying decrease in the number of births.

One other observation: It may just be my imagination, but there seems to have been a proliferation of singers in recent days. Maybe we’re just noticing more, or perhaps there are actually more whales singing now.

I’d always assumed that the prevalence of singing would be greater during the early part of the season rather than the latter, but maybe I was mistaken. In the past 10 days, we’ve come across 10 singers, and on Wednesday, we came across one of the most complacent and cooperative singers I’ve ever encountered.

Humpback whale calf Uatolu (#23, female), the second calf I’ve documented travelling
between island groups, thanks to help from Douglas Seifert

Tahafa Back in Vava’u
The big story this week revolves around injured baby humpbacks.

First, there was Tahafa, the injured male calf that I’ve written about extensively in previous posts.

Humpback whale calf Tahafa (#14)
with mom resting in a head-down position

Tahafa has, without a doubt, shaped up to be the star of the season. Over 33 days and through nine encounters, we’ve watched as this little calf has developed from a wee little tyke suffering from grievous bodily harm (see Part 3 for photos) into a happy, healthy young lad full of energy and confidence.

This alone would be amazing enough, but we’ve also now tracked this baby from Vava’u to Toku (accompanied by a long-term escort that mommy seemed to take a shining to) and back to Vava’u again. On 24 September, we again came across mom and baby, this time playing in the inner waterways of Vava’u. We had last seen the pair on 16 September in Toku, some 40km away.

As with our last sighting, mother and baby were not accompanied by the escort that kept them company for at least 14 days (1 to 14 September), suggesting that the parting of the ways I documented as taking place between 14 and 16 September was a permanent separation. (Refer to Part 6 for more details).

The good news is that Tahafa’s injuries seem not to have led to any serious long-term damage. Over the past month or so, the calf’s wounds have healed well:

Tahafa’s wounds are generally healing well

In our recent encounters, the young humpback has been extraordinarily playful…tail-slapping, breaching, flopping around…doing all the fun things that baby humpbacks do as they explore their surroundings:

Overcast skies didn’t stop Tahafa from enjoying himself

Happy, healthy humpback whale calf Tahafa playing near the surface

At this stage, I’m confident that Tahafa will make it through the season and head south with his mother.

He’s not completely clear of the woods though. The large chunk taken out of the anterior portion of his dorsal fin hasn’t entirely healed over. It looks as if some flesh is still exposed; viewed from the side, the base of Tahafa’s dorsal fin seems to have some tearing.

If you compare the photos below to the image I posted in Part 3 though, you’ll see that the wound appears much better than before, so at least there has been visible healing progress.

Tahafa’s wounds are mostly healed, except his dorsal fin,
which still has areas of exposed flesh

There has been some discussion/ speculation about what may have been responsible for these wounds, with theories spanning tiger shark attack, run-in with a boat, and ambush by a group of marine mammals.

Bear with me for a little longer, and I think I can set out a strong case for marine mammal attack, based on a series of images showing similar wounds on three other baby humpback whales I’ve ID-ed this season, and also upon information/ input from a couple of fellow photographers.

The Case for Marine Mammal Attack
Let’s start with the latest calf I’ve ID-ed, a female named Fafa (#44), which we came across on 22 September. Fafa and mother were not accompanied by an escort.

Though not quite as extensive as Tahafa’s wounds, Fafa’s injuries were apparent from the moment I saw her.

This calf was covered with small circular and semi-circular wounds, identical to those on Tahafa. Also like Tahafa, Fafa had multiple wounds distributed all over her body, as opposed to a single wound or wounds concentrated in one place.

Humpback whale calf Fafa (#44, female) re-entering the water after breaching.
Note the wounds all over her body.

Particularly egregious was an injury to the calf’s fluke, with a chunk taken out, resulting in a tear to her right fluke:

Large chunk missing from humpback whale calf Fafa’s (#44, female) fluke

Upon closer inspection of underwater photographs, there are marks that look like an impression left by a bite mark, sort of like what happens when you go to the dentist and he/ she takes an impression of your teeth. The bite marks are all small, suggestive of a relatively small mouth:

These marks on Fafa’s mouth look to be impressions left by
the upper and lower jaw of whatever animal attacked this calf

Fortunately, Fafa seemed unfazed by whatever trauma had befallen her, as the calf was playful and brimming with positive energy.

My encounter with Fafa got me thinking about another calf I had seen much earlier this season, Fitu (calf #7, photographed on 18 August).

I posted a picture of Fitu back in Part 2, when I noted the unusual clover-like marking on the calf’s back, magnified in the graphic below. Given the wounds I’ve since seen on Tahafa and Fafa, my belief now is that this clover-like pattern is also the result of attempted bites by a similarly sized mouth.

These marks on Fitu’s (calf #7) dorsal surface
look like unsuccessful bite marks

In addition, upon closer inspection of photographs of Fitu, I noticed what appears to be a dental impression on Fitu’s left pectoral fin, again perhaps the result of an attempted bite:

Possible bite impression on left pectoral fin of Fitu (calf #7)

While I was grappling with these data points, we had another re-sighting on 24 September, this time of Uanoa (calf #20, male), with mom and escort.

Uanoa’s mom has a prominent white patch on both flanks, which makes her relatively easy to recognise. The water was murky, skies overcast, and whales on-the-go when we came across them, so I only had one drop to take a look and get photos.

From mom’s white patch, and more importantly…the missing tip of the calf’s left pectoral fin, I was almost certain it was Uanoa, a hunch I was able to confirm later that evening after I downloaded images.

Uanoa (#20, male) is missing the tip of his
left pectoral fin, possibly from a bite

In isolation, the missing tip of the calf’s left pectoral fin might not mean much. But taken together with the wounds and markings on Tahafa, Fafa, and Fitu…I’d say there’s a reasonably high chance that the same type of culprit is behind all of these injuries.

Earlier in the week, Mark Strickland contacted me to suggest that Pseudorca crassidens, commonly known as false killer whales, might be more likely candidates for coordinated attacks on humpback whale calfs than pilot whales (I had previously suggested pilot whales as possible perpetrators).

Mark had an incredible encounter with these marine predators some years ago in Thailand, when he came across a bunch of them hunting sailfish.

To cut to the chase, Mark saw these pack hunters in action, chasing down and obliterating the large fish. A person in the water was stabbed through the leg and abdomen by the fleeing prey and had to be taken to the hospital for emergency treatment of a perforated colon. Fortunately, she made it through OK.

Anyway, given Mark’s direct experience with false killers (and my lack of such experience with them), I took his feedback seriously.

I then asked another friend, Douglas Seifert, for his thoughts, and he mentioned that false killer whale attacks are generally characterised by “raking” marks on their victims. Sure enough, upon close inspection, both Tahafa’s and Fafa’s bodies exhibited such marks.

Example of raking marks on injured calf Tahafa’s pectoral fin

Douglas also passed me copies of some peer-reviewed papers about Pseudorca, one of which made reference to another paper that documented false killer whales attacking and killing a humpback whale calf in Hawaii (Hoyt, E. 1983. Great winged whales, combat and courtship rites among humpbacks, the ocean-not-so-gentle giants. Equinox 10:23-47).

So…while it’s difficult to be 100% certain without witnessing an actual attack myself…I believe that the photographs of four injured calfs from this season (Tahafa, Fafa, Fitu, Uanoa), along with the feedback/ input from Mark and Douglas, make the case for a marine mammal attack (probably false killer whales) about as watertight as you can get.

This year certainly isn’t the first time I’ve seen injuries like this on humpback whale babies here, but it’s the first time I’ve had a critical number of well-documented/ photographed subjects to study, augmented by the advice and guidance of two knowledgeable friends.

Sing Me A Song
To round out the week’s experiences, we came across one of the most cooperative singers I’ve ever encountered. Perhaps, in fact, the most cooperative.

In reasonably calm water (with bad visibility unfortunately), this singer adopted the classic head-down pose and remained stationary with fluke at around 10-15 metres for 10-15 minutes at a times. When he came up, the whale didn’t move far, and when he went down again, he stayed shallow.

Most of all, the singer didn’t seem to mind our presence, even though it was clear that he was aware of the pesky little humans hanging around, listening to his solo performance.

One of the most cooperative singers I’ve ever come across,
in the classic head-down posture

One thing I’ve noticed is that the bass of this year’s song isn’t quite a “booming” as in previous seasons. Even when I hovered directly above this singer, the low notes didn’t reverberate through me quite as strongly as I’m accustomed to.

This has been the case with all the other singers we’ve encountered this year (14 to date), so I assume it’s a characteristic of this season’s tune.

2011 Humpback Whale Season in Tonga: Part 6

tony — Sun, 18 Sep 2011 02:44:55 +0000

What a week.

Since my last update, we’ve hit 40 ID-ed humpback whale calfs(!!!); re-sighted several babies we previously ID-ed; visited Toku again; been in the midst of a power-packed 8-whale heat run; come across humpbacks with split dorsal fins for the first time this season; been buzzed by a bunch of adorable baby reef sharks; swum among pilot whales; and even had a large pod of spinner dolphins accompany the boat for a good half hour or more.

The weather has finally been cooperative, so we had sunshine, clear skies and calm winds for the entire week. But…the low visibility that’s prevailed for the entire season actually worsened. It seems like there was some sort of mass spawning event around the recent full moon, which basically mucked the water up even more than it already was. Just perfect for underwater photography. Sigh.

Toluono (calf #36, male) relaxing at the surface

Calf Count
With 40 baby humpback whales ID-ed and counting, we are totally off the chart. I still have nearly two weeks left here, so I’m almost certain the total count will increase.

But by this point in the season, the number of newborns should begin to diminish. In a “normal” season (to the extent such a concept exists), I’d expect that we’d be approaching the tail-end of the birth bell curve, and that from this point forward, the balance of our calf encounters might begin to shift to a greater number of re-sightings, as opposed to new IDs.

This season, however, has proven to be mind-boggling in many respects, so it’s entirely possible that the birth bell curve stretches out for a while more.

In an average season, I’d expect the earliest sightings of newborn humpbacks to occur some time in July, with the latest being in October. This season, the earliest sightings were in late June, i.e., early.

It will be interesting to see if new calf sightings tail off sooner than expected, or if there is no “forward shift”, so to speak, of baby humpback births.

We ended the week with 40 ID-ed humpback whale calfs.
(black = 2008; blue = 2009; red = 2010).
Extracted from my 2010 humpback calf summary.

Also this week, I had my first “calm” encounters with mother/ calf pairs. For most of the season, females with babies have been “neutral” to “skittish”, meaning there have been some, but relatively few, encounters during which mommy humpbacks remained stationary and let their babies swim and play at the surface.

I finally had two such encounters this past week, although only one of the two was truly relaxed…little baby girl Tolunima (calf #35) and her mom.

In the other encounter…with Toluono (calf #36, male)…cow and calf were swimming, but when we entered the water for the first time, the mother skidded to a complete stop and rested at shallow depth, letting the calf explore its surroundings and us…before she arose from her afternoon snooze and continued on her high-pace trek southward.

Finally, we had three re-sightings this week:

- Seventh and eighth sightings of Tahafa (calf #14, male), more about this calf below;
- Second encounter with Tolutaha (calf #31, female);
- Second encounter with Tolufa (calf #34, male).

Tolunima (calf #35, female). This is the first mother/ calf pair I encountered
this season that was stationary while calf played above.

The Little Calf That Could
The star baby of the season has turned out to be Tahafa, the 14th calf we ID-ed. Since my first encounter on 22 August, we’ve come across this little boy whale eight times:

1. 22 August: First encounter, a day after hearing reports of an injured calf, reportedly attacked by a large tiger shark. As soon as I saw the calf, I realised that the stories of a large shark were inaccurate. There was no way the wounds were caused by a tiger or similar animal. The wounds were small, distributed all over the calf’s body, and for the most part shallow. Mother and baby were not particularly friendly, but the baby looked completely healthy.

2. 1 September: Shawn came across this mom and calf, and reported that they were calm and relaxed, a major change since our first sighting, which was a cause for anxiety. There was an escort present. He noted: “Baby seemed feeble and might require extra care. Lacking the spring/ charisma of most calfs. Seemed like the mom had to nose the baby up at the surface. Seemed like the escort understood this and was super respectful of the mom and calf. Sitting below until they came up. Initially, didn’t even know the escort was there.”

3. 2 September: Much to our relief, the baby looked healthy this time, and was quite playful, breaching on several occasions. Still with escort.

4. 3 September: Baby was again playful. Lots of remoras on the baby. Still with escort.

5. 7 September: Mom, baby, escort travelling. Escort breached and tail-slapped. Baby flopped and twirled at surface.

6. 9 September: Still with escort. Baby looking good.

7. 14 September: Found Tahafa with mom and same escort at Toku. Escort fought off multiple male challengers, up to five at a time. Mom and baby relaxed, both very friendly to swimmers. Baby extremely playful and inquisitive. Finally able to determine that Tahafa is male.

At one point in this extended encounter, one of the male whales was singing while swimming. I believe it was the escort, as it was directly beneath me in shallow water, and the sound literally “boomed” through me as I swam. This is not the first time I’ve been in the water when one of several male whales has been singing in an active competitive situation centering upon a mother/ calf pair. It’s not even the first time this season. I’m sure there is something to this. Perhaps it’s a dominance behaviour, intended as a warning to the primary escort’s would-be challengers?

8. 16 September: Sighted Tahafa again at Toku. This time, the escort was gone. We did not attempt to get into the water. Decided to leave mom/ baby alone.

Injured calf Tahafa together with his mother. The baby’s wounds have healed nicely.

So over a 26-day period, we’ve documented this injured baby eight times, witnessing the baby’s recovery from wounds due to some sort of traumatic encounter. We’ll probably never know exactly what happened, but one thing is for sure…there was no tiger shark involved.

My preferred guess is an assault by a group of marine mammals (such as pilot whales). Another possible explanation is a run-in with some sort of motorised craft.

In any event, the baby has fully recovered, and the wounds are for the most part healed. In our most recent encounters, Tahafa was unmistakably healthy, energetic and inquisitive…just like a baby whale should be. Hurray!

If we do come across Tahafa again in future seasons, it’ll be easy to ID him from the wounds, especially the missing anterior portion of his dorsal fin.

Escort Enigma
Watching Tahafa’s healing/ recovery process has been fascinating and rewarding, but there’s more to this story…

To start, Tahafa is the first calf that I’ve documented in both Vava’u and Toku, which are about 40km apart. Mom + injured baby (together with escort) swam many kilometres through open ocean, in areas I know are frequented by pack hunters like pilot whales.

This underscores my observation over previous seasons that Vava’u does not seem to be a place where whales stay with their babies.

They may give birth here and/ or visit for some duration. They may even return during a given season, but for the most part, Vava’u is a way station for them, not a permanent home for the season.

Recall also that both the mother and the calf seemed to become relatively calm and relaxed after the escort joined them, sometime between 22 August and 1 September. It’s certainly not the first example I’ve seen of an escort having a soothing effect on mom and baby, but it’s notable in this instance because of the extended period of association.

This is Toluhiva (calf #39, female). Here, the calf is nuzzling the escort,
demonstrating that escort whales can be on good terms with babies

Specifically, the same escort accompanied this mom and calf from at least 1 September to 14 September, over two weeks. Admittedly, I haven’t been meticulous about recording observations pertaining to escort behaviour prior to this season, but this one example illustrates that escorts can and do stay with mother/ calf pairs for extended periods of time.

At this juncture, I have no idea if this particular escort’s behaviour represents the norm here, or if this is an outlying case. But documenting this extended association has given me cause to wonder why escorts even bother accompanying females that already have babies.

The desire to mate would be a logical assumption, one that I’ve taken for granted to date.

But here’s the thing…if moms that show up in Vava’u do regularly mate with escorts (and many moms here seem to be accompanied by escorts), does that imply that those moms have babies in consecutive years?

Consider this possibility for a moment: If a mom mates while she still has a newborn, that would mean that she’d be pregnant while raising that newborn, and would essentially have to face the daunting task of raising a baby while incubating a new baby over the same 12-month period or so.

Then she’d have to return from the south next winter with yearling in tow, part ways with her baby from this season, and then have the next baby soon thereafter…possibly having to go through the whole ordeal again if she’s approached by yet another eager-beaver suitor(s).

I have previously collected data here (Mother of Chibi-chan 200816 same as mother of Floppy 200929; Mother of Scratches 200801 same as mother of Stitches 200904) to suggest that this scenario might be possible (and have also heard from friends in both Hawaii and Japan that there are similar examples there), but you know…it seems like a major undertaking for a female humpback, something that any sane female just wouldn’t want to do…and might not survive if she did.

So even though such behaviour appears to be possible, it seems a stretch to assume that it would be the standard scenario. The energy requirements to feed and raise a newborn + incubate another calf at the same time would be humongous.

Here is an excerpt from a paper that Karen was kind enough to forward to me that addresses this specific issue:

Escorts to mother/ calf pairs on the breeding grounds are invariably male (Glockner-Ferrari & Ferrari, 1985; Medrano et al., 1994), and it has been suggested by Darling, Gibson & Silber (1983) that escorts associate with lactating females in the hope of mating them if they come into post-partum oestrus. However, the high cost of lactation (Lockyer, 1987) makes it likely that a female who is simultaneously pregnant and lactating will be in poorer body condition during the year in which she is nursing the subsequent calf. The percentage of females that we have observed (Clapham & Mayo, 1990) with consecutive-year calves in the Gulf of Maine (a feeding area) was significantly lower than that recorded by Glockner-Ferrari & Ferrari (1985) from the Hawaiian breeding grounds. If this is not entirely due to a bias in sampling towards mothers off Hawaii, the difference may at least partly reflect higher mortality among second calves (those born after an interval of 1 year) prior to arrival in high latitudes. If this is indeed the case, then escorting a mother/ calf pair on the breeding grounds may be a strategy that is inferior to courting or competing for a female who is not currently incurring the expense of lactation.

- Clapham, Phillip J. (1996) The social and reproductive biology of Humpback Whales: an ecological perspective, Mammal Review, 26, 38

This is the escort whale that accompanied Tahafa (calf #14) for at least two weeks

To translate…the paper suggests that for a male humpback to mate with a cow that already has a calf might result in lower probability of his offspring’s survival, and thus not be a wise strategy. This intuitively makes sense.

But if this isn’t the normal situation, then why are so many mother/ calf pairs in Vava’u accompanied by escorts?

So far this season, 20 out of 40 (50%) females with babies we’ve ID-ed have been accompanied by at least one escort. In addition, 11 out of 27 (41%) mother/ calf pair sightings for which we have not established in ID have also involved at least one escort.

One possibility is that the presence of an escort somehow makes it easier for us to approach and ID mother/ calf pairs. I don’t ascribe a high probability to this, however, as the presence of an escort often makes it more difficult to approach females with babies, as I outlined in an earlier post.

Plus, even though I haven’t been tracking escorts in an organised manner during previous seasons, I know from experience that the association of escorts with a significant ratio of females with babies here has always been the case, at least for as long as I’ve been visiting Vava’u.

Of interest, the same paper, on page 40, suggests that the frequency with which males choose to associate with mother/ calf pairs may vary from location to location:

It is curious that, while lactating females are often at the centre of competitive groups in Hawaiian waters (Baker & Herman, 1984b; Glockner-Ferrari & Ferrari, 1990), their occurrence in such groups in the West Indies is far less frequent (Clapham et al., 1992). The absence of calves from most competitive groups in the latter region may reflect a preference by males for females who are not lactating (and are therefore in superior condition). However, why such a phenomenon should apparently not also be observed elsewhere is difficult to understand unless the frequency of post-partum oestrus differs between populations.

Taking this information at face value, it seems like the tendency of males to associate with mother/ calf pairs here resembles the behavioural patterns of humpback populations that visit Hawaii more than of those that frequent the West Indies.

Tahafa’s long-term escort. Scraped up dorsal fin…evidence of battle

A Few More Questions, Some Speculation
As I pondered the details of our multiple encounters with Tahafa, mom and escort, a few more issues came to mind.

Why are some escorts (like Tahafa’s) seemingly so loyal (spending at least 14 days by Tahafa’s and mother’s side, including crossing 40km of open ocean and doing battle with five or more aggressive males at a time on multiple occasions) and prepared to undertake bodily risk? (In one particularly spectacular conflict, I watched the primary escort ram nose-first into the belly of another male.)

Another head-scratcher…why, after spending so long with Tahafa and mom, did the escort suddenly disappear by 16 September, less than 48 hours after I had watched the escort engage in serious combat seemingly for the purpose of defending his access to Tahafa’s mom?

And one final twist…when we spotted Tahafa and mom on 16 September, there were dozens of hormone-raged males in the immediate vicinity (like right next to Tahafa and mom), including several that were in hot pursuit of other mother/ calf pairs, and at least seven that were body-slamming one another over bragging rights to what appeared to be a single female.

The question that pops to mind is…if Tahafa’s mom merited so much attention on 14 September (“territorial” aggression by the primary escort + challenges by many other males), then why, less than 48 hours later, was Tahafa’s mom essentially ignored by all the horny males in the area?

I certainly don’t have any definitive answers to these cetacean conundrums, but I’ve pieced together what might be a plausible narrative, one that I can maybe use as an initial framework for developing a better understanding of mother, calf, escort interactions here in the future. It’s pure speculation, trying to fit all the pieces together, but here goes:

What if female humpbacks (whether they are with calf or not) are able to advertise their reproductive status? So let’s say some females with babies go into oestrus while they’re around Vava’u, and they somehow communicate their reproductive readiness to the males in the area (pheromones? audio signals?).

Healthy, happy Tahafa (calf #14) with mom,
primary escort visible in background

Let’s say this takes place some time before she’s actually ready to mate, perhaps up to two weeks.

If Tahafa’s mom sent out just such a signal, and the escort (along with other males) picked up on it back in late August, then there may have been a contest for her acceptance, resulting in the presence of a primary escort with Tahafa’s mom by 1 September (the first time we noted the presence of the primary escort).

From that period forward, the primary may have fended off dozens of challengers, as the female continued to advertise her fertile status.

In this specific example, Tahafa’s mom (and Tahafa for that matter) seemed pleased/ comfortable with the primary escort, so she may not have actively sought to “accept” a different escort, or perhaps she did, but always ended up choosing to associate with the primary escort. In either case, the same primary escort prevailed.

The challenges may have culminated in the all-out assault of multiple males that we witnessed on 14 September, when the primary escort was challenged from left, right, above, below…basically everywhere…by two, three, sometimes five whales at a time, and not always the same whales, meaning the total number of challengers exceeded five.

The reason for the culmination may have been that the time for Tahafa’s mom to mate was near (full moon was two days earlier, on 12 September), and the challengers sensed an opportunity to usurp the primary escort. They could invest a little bit of time and possibly gain the right to mate. If they failed, they wouldn’t have invested too much time, and could quickly move on to something else.

By 16 September, mating was finished. Perhaps the primary escort successfully defended against all challengers and mated.

After that, the primary escort…being male, saw no reason to stick around and left. Other males, sensing no reason to court Tahafa’s mom, diverted their attention to the other receptive females in the area (several with babies, one without).

Tahafa and mom were left in peace…for the first time in several weeks…explaining why the pair were left alone even as wild heat runs and competitive groups coalesced all around them.

Whatever the case, Tahafa, his mom, and the primary escort that accompanied the pair have given me a reason to pay more attention to escorts in future seasons.

If you happen to have any insight into how plausible or not the speculative scenario above might be, please let me know!

Surrounded by humpback whales in a massive, high-energy heat run

Toku Revolutions
Besides the encounters with Tahafa described above, we also had a massive 8-whale heat run at Toku, one that literally took us in circles…around and around and around…as the whales snorted, slapped, smacked, lunged, and dived at high speed.

I’ve seen a lot of heat runs over the years, but this one ranked in the top five or so in terms of energy levels. My friends from the People’s Republic of China who were with me this week couldn’t get enough. Lots of hoots, howls and woohoos! all around.

I also photographed two whales with split dorsal fins there. This is such an unusual trait that I’ve been keeping track of humpbacks I see with dorsals like this, figuring that it’ll be relatively easy to recognise them in the future.

I hadn’t seen any all season (in contrast to five or so I photographed in 2010). Then on 16 September, I photographed two such whales, at the same place, at nearly at the same time. One was the mother of Fanoa (calf #40), and the second was one of the males involved in the big heat run.

One of the whales in the heat run had a split dorsal fin

And just to round out the week, I had a brief visit with a handful of cute baby reef sharks that came to check us out:

One of several baby reef sharks that buzzed us

And then some pilot whales, with a wee little one among them:

Pilot whales in the blue

In case you couldn’t tell, I’m running out of steam and can’t write much more.

My friends from China leave tomorrow, following which, I have several groups arriving from Japan…so I need to catch up on some sleep and recover from the week’s activities.

It’s overcast with a bit of rain today, but I certainly hope the great weather we had last week comes back.

Friends from China, overjoyed with their whale encounters