Is It a Bird or a Bear?

Cooper Island, Alaska, Aug. 14, 2009 — This summer I find myself looking at images obtained over the past month on Cooper Island and thinking “what is wrong with these pictures?” But I know that the images of polar bears walking around the colony, sleeping on the beach and approaching the campsite, things I could never have imagined before 2002, are the product of habitat degradation rather than any image manipulation.

Because of the frequency and type of bear encounters in August 2008, I was looking for some way to have an alarm that would let me know a bear was approaching the cabin. This spring, when Marc Cornelissen, an Arctic researcher who has worked on Spitsbergen, a Norwegian island, offered to loan me some tripwire alarms I could use around the cabin, I eagerly accepted.

I had met Marc in April 2008 when he was mentoring a select group of European students who had been chosen to be “ambassadors” for the Ben and Jerry’s Climate Change College. Marc was touring Alaska with the students to allow them to see where climate change was most rapidly occurring. (Ben and Jerry’s funded the college in part with proceeds from the sale of a “Baked Alaska” ice cream that had the tagline “If it’s melted it’s ruined”. Unfortunately, this flavor is only available in the U.K. and Europe.) I spent a day with Marc and the students in Barrow, making a presentation to them about my findings on Cooper Island and listening to their questions and concerns about climate change in the Arctic.

Marc’s bear alarms arrived in a surprisingly small shipping container from Holland just as the field season began. The four alarms each consisted of a small plastic box, about the size of a cigarette pack, with carabiner (a clip with a spring) on two sides. One carabiner was attached to a pin inserted in the box, which triggered the alarm when pulled. When deployed, a taut string runs from the alarm’s pin to a post or other vertical structure. Increasing tension on the string pulls the pin and triggers the alarm in the box. The high pitched warbling alarm is surprisingly loud.

I set up the alarms this summer on the door and window sides of the cabin. Having tested each alarm by doing my imitation of how a bear might approach the camp, I did feel more confident when sitting in the cabin, and especially when falling asleep. Unfortunately, the tripwire lines attached to the alarms proved very attractive to the snow bunting adults and young that feed near the cabin. One of the shortcomings for birds on the island is a paucity of places to perch and it turns out that if more than two buntings sit on the string at the same time, they can pull the pin and set off the alarm. The first two times the alarms were triggered were during the day, and I emerged from the cabin with my shotgun at the ready (and adrenalin extremely high) to see a small flock of buntings flying away from the cabin — and from the high pitched alarm. It was good to know that my granola and oatmeal were safe from any seed-eating birds that might be considering a raid on the cabin. While it is true that the number of people killed by Snow Buntings in Alaska is just one less than the number killed by polar bears, to avoid such false alarms I started to deploy the alarms only as I was going to sleep.

Having the alarms was especially comforting last Friday night, since a bear had arrived on the island during a strong north wind that day. After nosing around a bit the bear had quickly gone to sleep behind a large box about quarter-mile from my cabin, so I turned in as well. At 4 a.m. Saturday morning, however, one of the alarms went off. I looked outside expecting to see the bear running from the cabin, but instead found it sniffing and licking the alarm. The bear only ran away when I shouted and made it aware that a human was in the cabin.

Later examination of nest sites and the bear’s tracks showed that it had walked through the colony turning over nests and eating guillemot chicks before approaching the cabin. The only reason I can think for the bear considering the alarm as food is that guillemot chicks do make noises when their nest sites are lifted, and the bear might have thought that the alarm was the world’s most high pitched and loudest guillemot chick.

Two nights later I had quite a different experience, which I was able to capture on the motion sensitive cameras I use for monitoring feeding activity and other nest activity. A bear that was not on the island when I went to sleep approached the cabin at 3:30 a.m. Upon triggering the alarm it turned and ran from the cabin. Here’s some primitive stills from the video — shot in infrared — of the bear-alarm encounter (the edge of my cabin can be seen along the left side).

So both times bears triggered the alarm, the alarms performed their function – which was to alert me to the fact that a bear was within 2 meters of the cabin. And now I know that when I hear an alarm I might look out to see a bear running away from the alarm – or I might see a bear trying to eat the alarm. And I suppose if I hear a high-pitched, warbling bear I will have the relationship to it that Captain Hook had to a crocodile that swallowed the clock.

The alarms were the only really positive part of the two visits by bears this past weekend. While the bears in mid July had little interest in just-hatched guillemots, chicks now apparently have enough fat and mass to be of nutritional interest to the bears. The strength of the bears, and their desire to get to the chicks,is obvious from the damage they did to nests.

Both bears had to swim through rather rough waters to reach the island, and sleep, rather than food, appeared to be their primary interest. One bear spent all day Saturday curled up in the driftwood, during a substantial rain storm. The other made a small depression behind a large box and spent all day Sunday sleeping out of the wind.

So thanks to Marc Cornelissen for allowing me to sleep a bit more soundly in the Cooper Island “Bird House” — and also thanks for his arranging to have the Ben and Jerry’s Climate Change College donate funds to partially fund this summer’s field camp. My next post will be the official “State of the Colony” address, as the first guillemot chicks are reaching the age to leave the nest.

 

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Don’t Count Your Chickens Before They’re Fledged

Cooper Island, Alaska, Aug. 12, 2009 — Of all the questions people ask me about guillemots, one of the least common is “What the heck does ‘guillemot’ mean?”. This surprises me, since I would think that would be one of the first things people would wonder about the bird. It turns out that “guillemot” is the diminutive of Guillaume – the French version of “William”. But it also turns out that no one seems to know why the genus Cepphus — or in England the closely related members of the genus Uria — are called guillemots. When talking to school groups I sometimes mention that the name means “tiny bill” in French, and when compared to puffins and other alcids, guillemots do have a tiny bill. But that is certainly not how they got their name.

Diminutive guillemots have occupied my time over the past three weeks as I monitor the daily growth of the chicks. Guillemots emerge from their egg at about 35 grams and are continuously brooded by the parents for about six days. While in the nests the chicks provide a unique opportunity for study. One of the problems in studying seabirds is that they, by definition, spend much of their time at sea. Terrestrial researchers, like humans, can watch seabirds from shore or from a boat, but it is at seabird colonies, where there are lots of land-bound nestlings being fed by sea-going parents, that much seabird research is done. Studying the growth and survival of chicks can reflect local variation in the abundance and type of prey available to parent seabirds raising young. In recent decades, as short and long-term changes in marine ecosystems have become issues of concern, there has been an increasing awareness that seabirds, as “apex predators”, can be used to monitor seasonal and annual changes in marine ecosystems. This is especially true in the Arctic, where a lack of commercial fisheries and limited sampling, due to both logistical and funding issues, means that major changes can occur but go unnoticed by scientists and resource managers.

Black Guillemot parents and their nestlings have some characteristics that make them excellent monitors of prey (fish) availability. Reasons for this include:

• The limited foraging range of the species of about 25 km means there is a rather clearly delineated area being sampled. Compare this to albatross chicks being fed in Hawaii, whose parents may fly thousands of miles north to the Aleutian Islands for food.

• Parent guillemots return to the nest holding a single prey item sideways in their bill, so the type of prey being returned can be monitored by photographs or observations. Many seabirds return to the nest and regurgitate to feed their chicks, so that the prey being provided cannot be easily ascertained.

All of these characteristics have assisted in monitoring changes in prey availability in the waters off Cooper Island in recent years. Arctic cod, a high fat fish associated with cold waters, were the primary prey fed to chicks for first 25 years. There was some minor annual variation in cod availability with slower chick growth in some years but with large adult cod remaining the primary prey returned to nestlings. It was not until this century that we began to frequently see sculpin, a near shore bottom fish, being brought back to chicks in numbers later in the nestling period.

Sculpin are abundant in the near shore throughout the summer and guillemots apparently turn to them when Arctic Cod are no longer available. Sculpin are less fatty than cod and have a bony and horny head that can lodge in a chick’s throat. Some chicks appear to have a natural aversion to sculpin, letting them pile up in the nest site while waiting for an alternate prey.

Up until the last week, Arctic cod were readily available off Cooper, as evidenced both by growth rates and observations of fish, but as the last of the ice melted from just north of the island changes began to occur that I will discuss in a future post. The other factor that has become an issue this year in monitoring chick growth is the number of nests lost to polar bears and chicks killed by the horned puffins. This has reduced the sample size of chicks that can be weighed daily and parents that can be observed carrying fish.. With the late summer retreat of the pack ice, mid to late August has been the time when seasonal changes in prey have been most pronounced and this year there are fewer than normal chicks to monitor the changes in prey that will be taking place.

The reasons for the small number of active nests at this point in the breeding season are something I will discuss later this week. Suffice it to say the past ten days have demonstrated one of the shortcomings of using seabird nestlings as monitors of prey availability, in that a range of factors not directly related to guillemot prey can reduce nestling survival. Which is to say one shouldn’t buy guillemot futures in a bear market — a variation on don’t count your chickens before they’re fledged.

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Driftwood: Sign of a Changing Arctic

Cooper Island, Alaska, Aug. 9, 2009 — Driftwood lines in the middle of Cooper Island are important for nesting terns and waterfowl, but in any given year there typically has been little accumulation of wood on the island’s beaches. Until recently, the short duration and limited amount of ice-free water were not conducive to movement and deposition of driftwood. Hundreds of miles north of the tree line, driftwood on Cooper Island apparently comes primarily from the Mackenzie River. When the Beaufort Sea had limited open water, wood coming out of the Mackenzie would likely have had little chance to drift before it was frozen into the pack ice in the fall. Once frozen into the ice it might have stayed there for years given the minimal retreat of the pack ice in past decades.

This year’s unprecedented accumulation of driftwood on Cooper Island is one more sign of change in the Arctic. As the ice melted over the past month, pieces of wood that had been frozen in the ice are frequently seen floating offshore as they approach the island and now form a substantial line of driftwood along the entire north side of the island. It will take major fall storms to lift this wood higher on the island where it can provide nesting habitat. For now it provides some diversity during walks on the north beach.

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