NEWS FROM THE FIELD: A poor breeding season on Cooper island?

George is finishing up his second week on the island and the news are not super positive. There has been an extremely late snowmelt and guillemots laid eggs as late as they did in the 1970s: the first egg was seen on 24 June, while in 2015 the first egg was seen on 6 June!

But the timing of egg laying is far less important than what George observed for overwinter survival and population size. Only 70% of the birds that bred last year are in the colony. About a third of this year's breeding pairs are composed of two birds whose mates died over the winter. There are now only 45 nests with eggs. There could be as many as 15 more but it is clear the breeding population will be less than the 85 pairs of last year. In 2016 there were 100 pairs.

The only thing that is preventing an even larger decline in the population is the return of a rather large pulse (about 25) of the 2015 Cooper Island cohort. They have paired with widowed birds and not with each other. Immigration to the colony remains low with only one of this year's recruits being an immigrant.

George retrieved 10 geolocators (miniature devices measuring light levels which are used to reconstruct the trip of birds in the winter). The devices' data, once analysed, should help explain the increased nonbreeding mortality this year. Birds almost certainly wintered in the southern Chukchi this past winter as no ice formed in the Bering where they typically winter. Hopefully the activity logs can provide insights into how behaviour differed from earlier years with higher survival.