Could energetic limits to foraging range explain changes in inland nesting distributions of petrels on the Antarctic continent over the last 50,000 years?

Lead Supervisor: Dr Richard Phillips

Location: British Antarctic Survey, Ice Dynamics and Palaeoclimate team

Duration: 6 weeks

Suitable undergraduate degrees: Environmental sciences, Engineering, Applied Mathematics, or related field;

• Passionate interest in data science, analysing large volumes of data
• Python knowledge highly desirable
• Excellent written and oral communications skills, as well as the ability to work as part of a project team
• Highly motivated to learn and acquire new technical skills

Project background

Two species of small seabirds (snow and Antarctic petrels) breed in thousands to tens of thousands on nunataks (exposed rock) above the Antarctic ice sheet, up to several hundred kilometres from the coast. Radiocarbon dating of mummified Antarctic petrels and deposits of stomach oil spat by snow petrels in defence of their nests shows that nunataks in Dronning Maud Land, Antarctica were occupied by these species up to at least 50,000 years ago. However, there is growing evidence that periods of occupation alternated with periods of abandonment and subsequent recolonisation, with striking differences in timing between species and sites. One of the reasons why sites were abandoned and recolonised is variation in the extent of summer sea-ice cover in adjacent waters. During cold periods, open-water feeding sites may have been too far away from some nunataks for breeding to be viable. The aim of this study is therefore to understand the energetic factors that constrain seabird foraging, and hence whether environmental changes might explain cycles of occupation over the last 50,000 years.

Although snow petrels weigh only ~300g, and Antarctic petrels ~700g, they routinely fly >1000 km on foraging trips that can last a week or more. Snow petrels usually feed in leads (small areas of open water) within denser areas of ice pack. In contrast, Antarctic petrels feed closer to the ice edge (the Marginal Ice Zone), in lower sea-ice concentrations. Parents need to travel back-and-forth to the nest, returning every few days either to take turns incubating the egg or, once the egg has hatched, to feed their single chick. Hence the occupation history of each nunatak likely reflects the distance to the ice edge or marginal ice zone at critical periods during the breeding season. In this project, the student will use bioenergetics modelling to predict the maximum distances that adults can travel between feeding and breeding sites while still being able to successfully rear their chick.

This energetics model will require parameterisation using values from the literature and existing bird tracking data. It will take account of the field metabolic rate (energy use per unit time) of the adult when incubating or foraging, total time spent in flight, landing rate (which indicates prey capture attempts), calorific value of prey and stomach oil, fasting capabilities,  energetic requirements of the growing chick, chick meal mass and feeding frequency. By matching the outputs to cycles of occupation from the deposits, the project will help us understand colonisation processes in seabirds in general and provide insights into Antarctic sea-ice extent off Dronning Maud Land over the last 50,000 years.