Despite the flurry of front-page headlines reporting the all-encompassing reach of environmental change, the bulk of climate change studies have centred on terrestrial ecosystems, considering factors such as temperature and rainfall. However, other environmental elements may have been overlooked. In the marine environment, wind is a considerable component of the ecosystem that has been influenced by climate change. In the Southern Ocean, westerly winds have shifted poleward and increased in strength as a result of increased atmospheric pressure. Pelagic seabirds like the albatross are nomadic predators, counting on the winds in this region to reduce the cost of flight between their breeding and foraging sites. Curious about the impact of climate change on these charismatic animals, Henri Weimerskirch and others at the CNRS in France sought to determine the influence of Southern Ocean winds on the foraging ecology of the wandering albatross (Diomedea exulans), one of the most far-ranging pelagic seabirds. Ultimately, they hoped to understand what consequences this might have on life-history traits like breeding success and body condition.
The CNRS team combined over 40 years of records on breeding success and tracking data on the duration of foraging trips with measurements of foraging success and body mass of wandering albatross on Crozet Island, located in the windiest area of the Southern Ocean. Though it is known that wind boosts flight in this nomad, the results of this research come as quite a surprise given the usually negative impact of changing climate. The team discovered that for the wandering albatross, climate change has actually been a benefit!
Weimerskirch and his colleagues revealed that breeding success in this species has increased over the past 40 years. The risk of breeding failure is highest during egg incubation, a duty shared by both males and females in these birds. However, higher wind speeds mean shorter foraging trips, and shorter foraging trips mean shorter incubation shifts and a higher chance of breeding success for the albatross. In addition, the researchers realized that the body mass of incubating birds of both sexes has increased by 1 kg over the past 20 years, a hefty 10–12% of their bulk. They suggest that this enhanced physique may boost flight performance in gustier zones, perhaps even reflecting that the mass gain is an adaptive response to the blustery surroundings.
It isn’t often that climate change proves advantageous to the affected critters and these findings are also relevant for conservation, as the range of this species has shifted poleward in concert with the winds. This has reduced their overlap with tuna long-line fisheries, which are known to increase albatross mortality. However, this upbeat scenario may not last forever. Even breezier conditions forecast for 2080 could prove detrimental for albatross flight performance and if winds shift even further toward the poles, the island of Crozet may cease to be a refuge for this central-place forager.
- © 2012.