Interacting effects of sea ice and wind on Antarctic seabirds (IcESWAS)
Lead Research Organisation:
British Antarctic Survey
Abstract
Context: Climate change can have multiple effects on species. Interactions between these effects can be synergistic, potentially pushing species into unrecoverable declines, or antagonistic, with one effect mitigating another. We therefore need to understand not only the dominant mechanisms linking species to climate but also their interactions in order to forecast the overall impact of climate change.
Within the past decade, sea ice around Antarctica has begun to decline. This is particularly worrying because sea ice provides habitat for diverse marine organisms, controls primary production (plankton growth at the bottom of the food chain) and affects global heat and carbon cycles. Sea-ice decline is partly due to changing wind patterns, but wind can also impact polar animals directly, raising the possibility of synergistic effects.
Two species are particularly vulnerable to these changes: the snow petrel and the Antarctic petrel. These medium-sized seabirds currently number in the millions, and are two of the world’s most southerly vertebrates. They often breed far inland on the Antarctic continent but always feed at sea, usually in waters heavily influenced by sea ice. Like other central-place foragers (animals that, like humans, commute to and from a fixed location), their populations may be affected both by the availability of feeding habitat (sea ice) and the cost of reaching it (termed accessibility). Petrels commute using both flapping and soaring flight, sustaining the latter by exploiting wind and updrafts. Hence, while declining sea ice affects habitat availability, changing wind may decrease or increase habitat accessibility.
The challenge: Due to the extreme Antarctic environment, the mechanisms linking seabirds to sea ice and wind are poorly understood. More generally, there are few studies of the effects of changing habitat availability and accessibility, and their synergies, on central-place foragers, hampering predictions and planning for the effects of climate change.
Aims and objectives: Using snow petrels and Antarctic petrels as model central-place foragers, project IcESWAS aims to determine the effects of sea ice and wind now and in the future by meeting three main objectives: (1) Quantifying how wind affects flight type, flight costs, route choice and habitat accessibility. (2) Determining which foraging habitats are selected. (3) Simultaneously modelling the interacting effects of habitat availability and accessibility on productivity (breeding success), and hence population viability.
To do so, we will use miniature bird-borne loggers to track the fine-scale movement and behaviour of petrels foraging from three breeding sites bordering Antarctica’s Weddell Sea with differing sea-ice and wind conditions. Combining these results with remotely-sensed sea ice and wind data, we will build models of flight costs, habitat selection and productivity, and forecast population viability under different climate-change scenarios.
Potential applications and benefits: The immediate application will be to better anticipate how flying seabirds, which are major consumers in Antarctic marine ecosystems, will be affected by different climate-change scenarios. Results will inform UK, polar and international climate and environmental policymakers, and facilitate improved planning by wildlife managers and NGOs, for example by identifying key areas for marine protection. This will benefit both wildlife and human society. Theoretical insights provided by the project will benefit researchers studying other populations impacted by potentially synergistic threats. The analytical framework will be applicable to other wide-ranging central-place foragers – a diverse group that includes many birds, bats and seals that are key consumers in their respective ecosystems.
Within the past decade, sea ice around Antarctica has begun to decline. This is particularly worrying because sea ice provides habitat for diverse marine organisms, controls primary production (plankton growth at the bottom of the food chain) and affects global heat and carbon cycles. Sea-ice decline is partly due to changing wind patterns, but wind can also impact polar animals directly, raising the possibility of synergistic effects.
Two species are particularly vulnerable to these changes: the snow petrel and the Antarctic petrel. These medium-sized seabirds currently number in the millions, and are two of the world’s most southerly vertebrates. They often breed far inland on the Antarctic continent but always feed at sea, usually in waters heavily influenced by sea ice. Like other central-place foragers (animals that, like humans, commute to and from a fixed location), their populations may be affected both by the availability of feeding habitat (sea ice) and the cost of reaching it (termed accessibility). Petrels commute using both flapping and soaring flight, sustaining the latter by exploiting wind and updrafts. Hence, while declining sea ice affects habitat availability, changing wind may decrease or increase habitat accessibility.
The challenge: Due to the extreme Antarctic environment, the mechanisms linking seabirds to sea ice and wind are poorly understood. More generally, there are few studies of the effects of changing habitat availability and accessibility, and their synergies, on central-place foragers, hampering predictions and planning for the effects of climate change.
Aims and objectives: Using snow petrels and Antarctic petrels as model central-place foragers, project IcESWAS aims to determine the effects of sea ice and wind now and in the future by meeting three main objectives: (1) Quantifying how wind affects flight type, flight costs, route choice and habitat accessibility. (2) Determining which foraging habitats are selected. (3) Simultaneously modelling the interacting effects of habitat availability and accessibility on productivity (breeding success), and hence population viability.
To do so, we will use miniature bird-borne loggers to track the fine-scale movement and behaviour of petrels foraging from three breeding sites bordering Antarctica’s Weddell Sea with differing sea-ice and wind conditions. Combining these results with remotely-sensed sea ice and wind data, we will build models of flight costs, habitat selection and productivity, and forecast population viability under different climate-change scenarios.
Potential applications and benefits: The immediate application will be to better anticipate how flying seabirds, which are major consumers in Antarctic marine ecosystems, will be affected by different climate-change scenarios. Results will inform UK, polar and international climate and environmental policymakers, and facilitate improved planning by wildlife managers and NGOs, for example by identifying key areas for marine protection. This will benefit both wildlife and human society. Theoretical insights provided by the project will benefit researchers studying other populations impacted by potentially synergistic threats. The analytical framework will be applicable to other wide-ranging central-place foragers – a diverse group that includes many birds, bats and seals that are key consumers in their respective ecosystems.