Whale behaviour in Bermuda Print
Written by Andrew Stevenson   
Thursday, 24 April 2008 08:53

Since starting the Humpback Whale Film and Research Project in the spring of 2007 there are a number of observations I made during the first year, which are being reinforced by observations made this year. Last year I spent most of my time trolling up and down the South Shore with the occasional foray to Sally Tuckers and Challenger Banks. This year I have spent as much time on Sally Tuckers and Challenger as the South Shore. Aspects of humpback whale behaviour I've observed in all three areas put into question some of the basic suppositions I had heard before.

Feeding

Supposedly North Atlantic whales feed in the colder waters of the northern latitudes and not in their southern breeding/mating grounds or during their migrations.

It seems the North Atlantic humpback whales are not simply using the Bermuda seamount as a mid-ocean navigational waypoint or a resting stop. They are feeding here. There is ample evidence for this.

I have photographed at least one whale four days over a seven day period. If they were migrating northwards, why stay a week in Bermuda? Indeed, whales are sometimes seen moving south west along South Shore, contrary to their overall migratory route, which would be north.

For example, on the day of the full moon in April 2007, I set out from Devonshire Bay on a perfectly clear day with calm seas. Visibility in the water was perfect, so much so that the reefs some 70 feet below could easily be discerned from the boat. Almost immediately after coming out of Devonshire Bay we spotted three or four separate pods of whales about two to three miles offshore moving consistently in a westerly direction. We picked up one whale and paralleled him and matched his speed until he slowly approached the boat and almost bow-rode our wave. We were travelling at a consistent speed of about six knots. As we came close to the Sally Tucker shelf we noticed a ripple line at least a mile long parallel to the edge. This was obviously an upwelling and was further evidenced by scum or foam on the surface. For exactly this purpose, I had borrowed a funnel net with a bottle attachment from BIO Station, and towed the net for about 20-30 seconds along the ripple line. Here are photographs of what the bottle was full of. Krill, fish eggs, newly hatched fish and copepods. In other words, whale food.

On the other side of this upwelling were whales. I was in the water several times to try to film them but the water was so murky that at one point a whale swam under me and I didn't see him. This was in shallow water about seventy feet deep. Over the course of the next few hours we saw what we estimated to be scores of whales. All of this activity took place on the day of the full moon. After the full moon we couldn't find any whales for some days. They had all gone, presumably continuing their way up north. This was also what had happened the previous month, during and after the full moon in March, 2007.

This year, 2008, the weather around the full moon in March prevented me from gonig out. But in April the same thing happened on the full moon as in 2007. On the days just before and just after the full moon on April 20th and April 21st there were as many as eleven fishing boats moored on the point at Sally Tucker's in about seventy feet of water. They were bottom fishing successfully for hind and bringing in large specimens. That morning we observed a whale on the point apparently feeding along the ledge, going down consistently for fifteen minutes at a time. Later I filmed a pod of five whales swimming amongst the fishing boats for about 45 minutes before they started moving along the edge to the north east. I heard anecdotal information that the previous day the whales had been snagged on hand lines.

We also followed a mother and calf from Challenger to Sally Tuckers the Monday afternoon. They swam at a consistent speed of four knots on the same heading to Sally Tuckers. At the point of Sally Tuckers they turned sharp right ninety degrees and began feeding along the edge at 180 feet, submerging for ten or more minutes at a time. Two days after the full moon all but two fishing boats had gone from Sally Tuckers and for the first time in weeks, we didn't see any whales, although I did see four spouts northeast of Sally Tuckers. We could not find these whales again and given our route over the flats towards Chubb Head I believe these whales must have been moving fast past South West Breaker and along South Shore. This was corroborated a day later by Explorer who had one whale in sight after a day of searching. That one whale moved consistently at four knots along South Shore towards the north east.

I have often observed whales diving consistently on the edge of Sally Tuckers and Challenger Banks. They will dive for seven to twenty minutes at a time, mostly staying in one area, although sometimes moving slowly along the edge, generally in water about 150-200 feet deep. This feeding behaviour increases as we get closer to the full moon.

I wonder if the whales are deliberately planning to be around Bermuda during the full moon to feed, and then immediately afterwards continuing on their migration. Stragglers, perhaps mothers with calves and their escorts and challengers who transited the ocean more slowly than expected start drifting into Bermuda waters again some days after the full moon. Sometimes these whales are clearly on a mission, moving steadily along South Shore at a consistent speed whereas on Sally Tuckers and Challenger they seem to be stationary, or moving haphazardly around in circles. As the full moon comes closer, any whales migrating to Bermuda might wait to wait to see if they can pick up food around the full moon. Presumably there is something spawning at the full moon and this is bringing in the predator zooplankton and the fish. There must be a connection between the full moon, all the fishing boats at Sally Tuckers, and the sightings of whales in the same area.

This year, where all the fishing boat activity was taking place on the hind grounds, and where the whales were swimming amongst the moored fishing boats, I observed brown streaks on the surface along the edge. Judie Clees on Challenger saw the same and quite independently we both collected samples in bottles. Dr Wolfgang Sterrer at the Aquarium and Dr Ross Jones and Dr James Wood at the BIO Station could not positively indentify the examples. Had we preserved them properly they might have been alive and continued their cycle and been identified. Next time.

I suspect the whales are not just feeding on plankton, but on schools of small fish as well. I have seen small fish thrashing around on the surface when I know there are whales down below them. I have seen at least on one occasion a bubble cloud with seven whales below. Could they be cooperatively feeding as they do up north?

That the whales feed in Bermuda should come as no surprise. They have been starving in the Caribbean for some months and if they can pick up snacks here in Bermuda on the way north to give them sustenance, then why not hang around here for a while and get some snacks? And it makes sense that we only see them on the way north when they are starving and chasing food and not when they head south, when their stomachs are full after a summer of feeding. I need to do is collect some whale poop, analyze it, and prove not only that the whales have been feeding, but hopefully what they have been feeding on! One big whale poop would do the trick!

Although we didn't get a whale poop sample, we did get a photograph of a whale having a poop! Here it is:

 

Resident Whales?

If you check my "Whale Diary" entries, you'll see that observers on the South Shore have seen whales consistently from December through January and February to the months of March and April. Is this because we have resident whales wintering here in Bermuda? According to archival records, whales did stay around Bermuda in the winter months. Whether these sightings are indeed a resident whale population or an overlap of whales heading south and whales heading north, I don't know yet. Some whales don't arrive in the Caribbean until February so it's entirely conceivable that a whale seen here in December and January could be a whale heading south still, although with their blubber store full, there would be no point hanging around here.

I think it is entirely possible that the whales we see here in the winter months may be a small resident pod. Who would be in that resident pod? Females, is my guess. Why? I've seen juvenile males as young as two years old and full of testoserone carry on in the fracas and party atmosphere of the Caribbean as if they were ready to mate, even if there were no females willing to take them on. Like most guys of any species, these juvenile malles think they are going to get lucky against all the odds. But what about the juvenile females up to five or six years old? Why would they go south to be harassed by males when they aren't ready to breed? And what about older females who no longer can or want to breed? Perhaps some of these young and old females would stay around Bermuda. The water is relatively warm, certainly warm enough for a whale, and instead of starving and being harassed by males, they can feed occasionally here and have a prolonged winter hen party! Make sense to me. What would be great is to get out on the water when these December/January whales are here and photograph their flukes, take a look at their sizes, photograph their dorsal fins, and make an educated guess as to their age and sex.

Next year!

"Yearlings"

My observations on mother and calves challenge the precept that humpback mothers abandon their calves at a year. If you check the video footage on YouTube called 'Mothers and Calves' you'll see the last sequence of videos is of what appears to be a very fat yearling of 15 months or more and about 25 feet. The calf is very very fat, has obviously not been starving all winter, and is accompanied by what appears to be his mother, a fully grown emaciated lethargic whale of 45 feet. The only explanation for the fatness of the calf is that he is still feeding from his mother. She is so thin and lethargic because she's been feeding him all winter. Of course I don't have genetic sampling that could prove this is a mother and calf, but the video footage says it all. Is this just a spoilt 'mama's boy' or is this the norm? It makes sense to me that mothers would 'abandon' their calves into the second summer of feeding up north, once the second migratory crossing of the oceans has been safely made and when the calf is likely to be able to feed itself.

The role of mid-ocean seamounts in the migration patterns of humpback whales

The major discussion point I have now is whether the humpback whales are using ocean seamounts such as Bermuda as a navigational waypoint to assemble into family pods before returning to their habitual feeding grounds up north. During their breeding/mating months down in the Caribbean over the winter the humpback whales mix freely with other humpbacks and travel over some distances. This makes sense from a genetic point of view. But when they feed up north they maintain site fidelity, meaning they return to the same bays with very little variation annually.

Given the fact that 25-33% of humpbacks bear Orca (killer whale) bite marks on their flukes, the humpbacks may travel in large protective pods while running the gauntlet of Orcas further north.  Based on observations, I surmise that the humpbacks form into larger pods while in Bermuda, and probably on other seamounts to our north and east, and opportunistically feed on upwellings on these ocean seamounts during this assembly period.

Bermuda is unique as a mid-Atlantic Ocean seamount that rises to the surface, allowing human habitation. Argus and Challenger Banks are two other seamounts just 25 and 15 miles to our southwest, and there are numerous others to our north and east, which don’t rise to the surface. From a whale’s perspective a seamount that doesn’t break the surface of the ocean is still a navigational waypoint, assembly area and a convenient source of upwelling currents, conveying scattering layers of food closer to the surface.

Allied Whale, College of the Atlantic will be searching through their 6,500-whale fluke catalogue to send me all their ‘Bermuda whale flukes’. If we match whales seen these past two years with whale flukes photographed in Bermuda from past decades, then we can begin to deduce that not only do the whales maintain site fidelity to their northern breeding grounds, but also maintain site fidelity to the ocean seamounts as well. This might be a first step in showing the humpbacks use these seamounts regularly as assembly areas.

Singing in Bermuda

Related to this discussion point is the possibility that the humpback whales are ‘singing’ during the migration as a call to bring together family members on the ocean seamounts before continuing northwards in a protective social unit, and not as an aspect of mating (as has been shown down in the breeding grounds). For whales migrating northwards from the Caribbean in the spring, Bermuda (including Challenger and Argus) is one of the first and possibly one of the more significant seamount assembly areas. It also happens to lie halfway on the rhum line between Silver Banks, Dominican Republic and Newfoundland.

On several occasions I’ve heard a whale singing all day while a social unit of four up to ten whales form and break up and form up again within a five-mile radius. This activity may continue for some days. Staying out at Challenger overnight we have heard singing non-stop throughout the night and the day. I have been in the water with a singing whale out at Challenger and although I could not see him, his ‘songs’ rattled my ribcage with their power and intensity. Are these whales ‘booming’ their presence to other whales? If all manner of creatures can recognize the cries of their offspring amongst thousands, then the humpback whales can certainly recognize individuals from their ‘singing’.

For example, one day we set off early and spotted a single whale feeding on the point of Sally Tuckers. A whale feeding will typically dive every eight to twelve minutes along the edge of a shelf, often in 120-180 feet of water. We radioed the whale watching boats that there was a whale feeding in that location. By keeping track of the movements of the whales the commercial whale watching boats serve as useful ‘satellite tags’. While they headed to Sally Tuckers we continued to Chubb Head where we found two whales lolling about in 70 feet of water. This seemed like a promising occasion to film them in the water. Unfortunately we lost them, despite the shallowness of the shelf. By the time we found them again three commercial whale watching boats were headed our way.

There’s very little chance of getting in the water with whales to film them when multiple boats are around so we headed over the shallows towards the point at Sally Tuckers when we came across a single whale. We lost him almost immediately in only fifty feet of water. In an attempt to spot actually him underwater I jumped. While I didn’t see him, I heard his singing.

I was in the water with the singing whale in the shallows off the Bermuda shelf and could see the three whale-watching boats approaching us. They were following the same two whales we had seen earlier and these two whales were heading directly towards the singing whale. The whale watching boats served usefully as ‘tags’, revealing the exact position of the other two whales. When the three whales joined together they set off for the point at Sally Tuckers where they picked up the single whale we had seen feeding. Soon there were five whales and as the evening went on we observed seven whales in the group. Filming them in the water I realized the social unit had grown in fact to ten whales and with sunset approaching they moved consistently at four knots in a north-easterly direction to parallel our South Shore.

This was not the first occasion over the two seasons when I have seen a social unit of 7-10 whales form by late afternoon or early evening to begin a deliberate and consistent speed and direction to the north-east, their route of migration. These are behavioral patterns that suggest the whales mill around for some days on the Bermuda seamounts before forming a large social unit and continuing their migration north.

There is also the possibility that females, too old or young to breed, over-winter on these seamounts where they can still feed rather than join in the mating rituals further south in the Caribbean where they have no access to food. I hope to collaborate with Bermuda’s commercial fishermen this winter to have them keep a look out for whales in the November to March period and to let me know if they see whales during those months.

Observation and filming work on the project this year was facilitated greatly by having the support of numerous volunteers and in particular, boat captains. In addition to having the use of David Saul’s Phidippides, Bob Steinhoff on Dom Perignon, Michael Smith on Sea Slipper and Geoffrey Gardner on Windrush provided their boats and expertise. For the second year, Camilla Stringer the Youth Volunteer Coordinator at the Bermuda Zoological Society was indispensable to onshore and offshore facets of the project and she’ll be sadly missed when she leaves the island.

Summary of achievements halfway through the project to June 2008: 

Over 500 hours on the water finding/observing whales

  • Over two hours of underwater high-definition video footage of humpback whales
  • Over five hours of above water footage of humpback whales
  • Observations and footage and photographs not only from Bermuda but also from the northern feeding grounds in Nova Scotia and the southern breeding grounds in the Caribbean
  • Although not included in the original budget or project description, establishment of a comprehensive website on humpback whales www.whalesbermuda.com so that students and teachers can access a Bermuda-specific website on the humpback whales
  • www.whalesbermuda.com is an educational tool that teachers and students are already using prior to personal visits by Andrew Stevenson or BAMZ/BZS BUEI educators
  • www.whalesbermuda.com is a rapidly growing educational resource that is already available and more dynamic as a teaching aid than a static documentary film
  • 10,000 hits on this website already since its establishment in the spring of 2008
  • 14 video clips of humpback whales in Bermuda on youtube with over 30,000 hits
  • Numerous schools, children’s organizations and clubs including over a thousand students have already had the benefit of Andrew’s personal talks
  • BUEI and BZS/BAMZ have had access to Andrew’s involvement in their after school programmes
  • Close ties to BZS’ and BUEI’s after school programme staff
  • A Keynote (PowerPoint) presentation has been prepared and can be left at BUEI, BZS/BAMZ and schools for teachers to have a finished, self-contained, prepared lecture with text, photographs and video clips on humpback whales
  • A photographic display of humpback whales at Kaleidoscope Art Gallery where school classes were brought in for presentations
  • Numerous articles in the Royal Gazette, Mid-Ocean News, The Sun and RG Magazine
  • Close ties with Greenpeace and Sea Shepherd Conservation Society
  • Close ties with Allied Whale, College of the Atlantic and Professor Hal Whitehead at University of Dalhousie
  • Maintained ties with Whale Quest in Hawaai and with Greenpeace humpback whale research projects in the South Pacific

Summary of Findings and Points of Discussion 

Evidence that humpback whales are feeding in Bermuda on ‘krill’, copepods, fish eggs and fish including photographic evidence of what the whales are feeding on and a whale excreting while lobtailing

  • Evidence that humpbacks presence in Bermuda waters peaks around the full moon
  • Evidence that the deepwater canyon between the Bermuda and Challenger Banks is frequented by beaked whales including sperms and Cuvier beaked whales feeding on deep water squid
  • Evidence that humpback whales do not abandon their calves after a year and the possibility that the mothers continue to feed their calves through two seasons in the Caribbean and then abandon their calves up north in the feeding grounds during their second summer
  • Evidence that the humpback whales are not simply migrating by Bermuda. At least one whale has been photographed and filmed four days over a week-long period
  • Evidence that whales are using Bermuda’s shallow waters for protection and to rest after their migration here from the Caribbean
  • Evidence that whales are using seamounts such as Bermuda to gather into family pods prior to running the gauntlet of Orcas and sharks in their northern feeding grounds. 25-33% of North Atlantic humpback whales have Orcas teeth scars on their flukes or dorsal fins
  • Suggestion that humpback singing in Bermuda may be relevant to whales assembling into their family pods
  • Suggestion that as the first major seamount on their migration north, Bermuda could be a significant gathering area for humpbacks
  • Suggestion that humpback whales are using other seamounts to our north also as gathering points and may linger on these seamounts for a week, opportunistically feeding while waiting for family members to assemble
  • Suggestion that similar fluke patterns in a pod is an indication of genetic ties and an indication that the whales are traveling in family pods
  • Suggestion that ‘breath holders’ are male and female and their ‘breath holding’ activity could be a prelude to mating
  • 9 of our ‘Bermuda’ whales have been matched to whales in Nova Scotia, Newfoundland and the Caribbean (Dominican Republic, Puerto Rico, British Virgin Islands)