Readers’ wildlife photos (and video)

Bruce Lyon, professor of ecology and evolution at The University of California at Santa Cruz, sent us another photo-and-video-studded tale of his adventures, this time on a whale-watching trip. His notes are indented.

In mid October I went on a whale watching cruise with Sanctuary Cruises out of Moss Landing, California. Every time I go out with these guys into Monterey Bay we see something special, and this time was no different. Some evolutionary biology colleagues were on the cruise and also witnessed the spectacle I will describe (John Thompson and his wife Jill, and visiting seminar speaker Pedro Jordano from Spain). John and Pedro are leading experts on coevolution.

Part way through the trip, Chase Dekker, the cruise naturalist and photographer, noted four orcas (Orcinus orca) being frisky. They briefly played with an ocean sunfish (Mola mola) on the surface, and then moved on. Chase later noted that the orcas, far off in the distance, were showing behaviors typical of hunting behavior, like tail slaps, so went closer to see what was up. It turned out that orcas were harassing a flightless rhinoceros auklet (Cerorhinca monocerata), a close relative of the puffins. The auklet was flightless because of its molting strategy—a variety of waterbirds (ducks, coots, some seabirds) shed all of their flight feathers at the same time and become flightless for a period of time. As a result, the auklet was a sitting duck for use as a toy by the orcas.

Below: A rhinoceros auklet—this was not the victim.

Below: An orca approaches the auklet, possible looking to see where the bird is. The bird was pretty good at evading the whales.

Below. The auklet skitters out of the way of the orcas.

Below: The orcas were not trying to eat the auklet but instead were trying to smack the bird with their tails. The three shots below show a couple of tail smack attempts. Based on the photos, its looked like the bird avoided  the full force of the tail in these cases. We saw at least 20 of these attempted tail slaps over 25 minutes. These chases and attacks were fascinating (in a morbid way) to observe but readers will be happy to know that the auklet got away in the end.

Below: Pending doom—the light coloration shows an orca belly just below the surface on an approach to smack the bird.

Below: A couple of times the bird got up on the orca’s back while the orca swam on the surface, apparently looking for the bird. Smart move.

Below: Chase Dekker sent his drone up to get an aerial view of things and got some amazing footage of what the orcas were up to below the water. The video shows that the orcas often tried to line up the auklet but the bird was then able to scamper out of the way. The bird is tiny relative to the orcas so you have to look carefully to see it in the video; watch for its movements. [JAC: it’s pretty obvious. Poor bird!]

This was an amazing spectacle to watch but it is not entirely clear why the whales were doing this. The Sanctuary Cruises folks have spent many thousands of hours on Monterey Bay over the years and have not seen this behavior before. A couple of different studies in British Columbia have reported harassment of flightless seabirds. Based on the caloric content of a bird, and the repeated effort the whales invested in trying to smack the bird, it seems this behavior is not simply about the whales trying to get a meal. In a British Columbia study, prey that was killed and consumed was almost entirely comprised of marine mammals, but seabirds comprised 30% of the animals that were harassed but not consumed. So perhaps seabirds are for playing with but not eating.

There are distinct types of orcas that differ in diet and It is perhaps telling that this behavior has only ever been observed in ‘transient’ type orcas that specialize in marine mammals. Based on the literature, these transients often stun their prey with their tails. The orcas in Monterey Bay are also mammal-eating transients so we suspected that they may have been playing and practicing their hunting techniques on a hapless bird. It is also possible that this behavior involves teaching hunting techniques to younger less experienced animals—there were two smaller, younger orcas in the group.

Orcas were not the only thing out on the bay harassing birds that day—we saw lots of jaeger (relatives of gulls and terns) chasing elegant terns (Thalasseus elegant) and robbing them of their prey. Jaegers are ‘kleptoparasites’ that make a living, particularly in winter, chasing other birds and forcing them to drop their prey, usually fish. Outside of the Americas jaegers are called skuas.

Below: An  elegant tern has just captured a fish by diving in the ocean and tosses the fish in the air to get a better grip. If jaegers see a tern catch a fish they will often make a beeline for the tern and begin to chase it. The terns try to evade but jaegers are fast and maneuverable and a dogfight style aerial battle typically ensues. The jaeger usually wins—the tern drops the fish and the jaeger snatches it out of the air. If the tern has already swallowed the fish it will regurgitate it to get rid of the jaeger.  The jaegers were too far to photograph on the day we saw the orcas but I will include some photos from another trip when the jaegers were close to the boat.

An immature pomarine jaeger (Stercorarius pomarinus) lines up an elegant tern. The rounded central tail feathers and large amount of white on the wing tips identify this as a pomarine, and the dark coloration means it is a young bird.

Sometimes two or three jaegers get in on a chase. Here two parasitic jaegers (Stercorarius parasitic) go after an elegant tern.  Parasitic jaegers have pointed central feathers that differ from the round feathers on a pomarine.

Below: There are also jaeger wannabes—Heermann’s gulls (Larus heermanni). Heermann’s gulls are not full-on pirates like jaegers, but they often do chase birds to try to steal food. Here some gulls join a chase led by a single parasitic jaeger, the dark bird closest to the falling fish that has just been dropped by the tern. The rest of the birds are gulls.

Below: the jaeger got the fish.