Arctic birds’ breeding and wintering grounds are warming, and that hurts them coming and going
Timing’s Off: Arctic birds’ breeding and wintering grounds are warming, and that hurts them both coming and going
Whenever I am asked to comment on the impact of climate change on Arctic birds, two words immediately pop into my mind: winners and losers. And the former are in a very small minority among the 85 bird species that breed in the globe’s northern regions. Being highly mobile creatures, birds will not be as hard hit as those organisms living year-round in the Arctic. But both breeding and wintering grounds will be affected.
One of the most critical issues involves timing. According to one large-scale study, birds are initiating egg-laying at an average rate of 6.6 days earlier every 10 years. The common murre, a seabird breeding widely throughout the Arctic, is 24 days earlier per decade. This is a bad thing because raising young is no longer matched with the time of best food availability. This has two negative effects: parent birds are unable to feed their offspring sufficiently; and later, fledglings will be unable to find adequate food to fatten up before migration.
Rising temperatures affect migration too: birds are migrating earlier because of warming spring temperatures. A 63-year study of 96 long-distance migrant species concluded that more than a quarter of them are arriving earlier. But many of these same species are not returning north any earlier. Since they cannot know what weather and food conditions are like on their breeding grounds in the Arctic, they may well arrive to discover there’s barely enough to survive on, let alone fatten up enough to produce eggs. Specialist species that eat only one or two foods will be especially hard hit. For example, ivory gulls, which specifically forage along disappearing sea ice, have declined by 90 per cent in just the last 20 years.
With entire ecological communities being disrupted by climate change, Arctic birds are challenged by a whole army of new parasites, predators and competitors to which they are not adapted. Thick-billed murres breeding in northern Hudson Bay are experiencing higher egg loss and adult mortality due to a combination of heat and greater numbers of mosquitoes. Habitat changes can also be indirect, as warmer conditions coupled with less snow and ice bring more tourism and resource development with all their associated infrastructure to the Arctic.
Scientists from the University of Queensland in Australia created a research model that took climate breeding conditions for 24 Arctic bird species and projected them into 2070. They gloomily predicted that more than 80 per cent will lose virtually all of their breeding habitat.
In a research report from the Wildlife Conservation Society in the United States, nine species were identified as either highly or moderately vulnerable due to changes specific to Alaska (not taking into account changes elsewhere in their range). Of the two most vulnerable one is the gyrfalcon, for decades now my favourite bird. Other, long-term gyrfalcon studies in Greenland reveal significant incursions of more aggressive peregrine falcons into their hunting grounds and their nests. Then again, the peregrines are having their own climate change problems in Greenland: massive increases in rainfall (a whole season’s worth falling in a mere three hours) is causing peregrine nestlings to drown or die of hypothermia. Falcon experts there feel it is just a matter of time before one of the two species will become extinct.
These are just a few of the losers in the reality that is climate change.
According to one large-scale study, birds are initiating egg-laying at an average rate of 6.6 days earlier every 10 years. This is a bad thing because raising young is no longer matched with the time of best food availability