Perhaps more remarkable, in 2000 and then again in 2003, a solitary bear actually climbed onto cliff ledges to consume murre chicks and eggs, also on Coats Island.
Prior to 2000, no such behavior had been observed during 17 years of study of the Coats Island murre colony, but Smith and his co-authors suggest that the incidents they witnessed may not be isolated ones:
Although bears have been observed to eat eggs previously, accounts of this behaviour seem increasingly common ...
They suggest the reason for the apparent increase in such predation is timing. The first polar bear sighting of summer on Coats Island advanced by approximately 20 days between 1985 and 2007, which correlates almost exactly with observed increases in break-up of summer sea ice in Hudson Bay over that same period.
Conversely, the nesting date of snow geese on Southampton Island has advanced by only two days per decade since 1968, while that of thick-billed murres on Coats Island has advanced by five days since 1988. In other words, the birds' nesting season now increasingly overlaps with the polar bears' presence on land, whereas previously it generally did not do so.
The consequences for the targeted bird colonies were catastrophic: on three of the four occasions, every available egg was eaten, and on the other occasion, the great majority of eggs was consumed.
The authors conclude:
ur observations demonstrate an earlier arrival of bears to land in this region, suggest an increase in their consumption of eggs and highlight the complexity of ecological interactions that may occur in a changing arctic environment. The recent intrusions of polar bears onto near-vertical cliffs to consume eggs and chicks of thick-billed murres, a potentially hazardous situation for bears, further demonstrate the lengths to which these opportunistic animals may go to supplement their diet during a longer ice-free season.
Photographs copyright Kerry Woo