Foraging movements and migration in auks
During the chick rearing period, how do razorbills (Alca torda) provision their chicks; where do they forage, and how deep do they dive? Why do razorbills breed later than conspecific common guillemots (Uria aalge)? Also, how do data loggers affect behaviour in alcid species? These are some of the questions we hope to help answer with our study at the beautiful Baltic island of Stora Karlsö, in collaboration with researchers from the Baltic Seabird Project.
Combining data from guillemots and razorbills will allow a comparison of the foraging behavioural ecology between the two species. This may help answer an outstanding question of Baltic Sea ecology around Stora Karlsö; why do razorbills breed later than guillemots? It does not appear to be due to different diets, as previous studies at the island suggest both species feed on clupeid species, both herring (Clupea harengus)and predominantly sprat (Sprattus sprattus).
Diving and flight abilities
A potential answer is that the two species differ in their diving and flight abilities. A recent study suggested that since razorbills have lower wing loading than guillemots, they follow a different foraging strategy. Razorbillsare travelling further, but diving less deeply while guillemots fly shorter distances due to their costly flight, but are able to dive more deeply and for a greater duration since their smaller wing area is beneficial fo diving. It will be interesting to see whether a similar difference in foraging strategies between the two species is apparent in the Baltic. Photo: Tom Evans- 1 of 5
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