R.H. Drent passed away on 9th September 2008
Skipping the Baltic: the emergence of a dichotomy of alternative spring migration strategies in Russian barnacle geese
Article first published online: 9 OCT 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Journal of Animal Ecology
Volume 78, Issue 1, pages 63–72, January 2009
How to Cite
Eichhorn, G., Drent, R. H., Stahl, J., Leito, A. and Alerstam, T. (2009), Skipping the Baltic: the emergence of a dichotomy of alternative spring migration strategies in Russian barnacle geese. Journal of Animal Ecology, 78: 63–72. doi: 10.1111/j.1365-2656.2008.01485.x
- Issue published online: 11 DEC 2008
- Article first published online: 9 OCT 2008
- Received 20 March 2008; accepted 1 September 2008; Handling Associate Editor: Alexandre Roulin
- arctic breeding;
- global change;
- migratory timing;
- 1Since the early 1990s, an increasing proportion of barnacle geese, Branta leucopsis, bound for breeding sites in the Russian Arctic delay their departure from the wintering quarters in the Wadden Sea by 4 weeks. These late-migrating geese skip spring stopover sites in the Baltic traditionally used by the entire population.
- 2Individual geese from an arctic colony tracked by satellite or light-level geolocators during spring migration in 2004 and 2005 predominantly followed the new strategy, but a minority still maintained the traditional pattern. Despite a spread of more than 50 days in departure date from the Wadden Sea, both early and late departing females laid their eggs within the short time-window conferring breeding success.
- 3The spread of these new migration routines coincided with a strong increase of overall numbers and the exploitation of new spring staging resources in the Wadden Sea. Counts from Estonia demonstrate that numbers have levelled off recently at the Baltic staging sites, suggesting that the capacity of these staging sites in spring has been reached. Although onset of spring affects migratory timing in barnacle geese, it cannot explain the observed delay in departure from the wintering grounds.
- 4We hypothesize that the new migratory strategy has evolved in response to increased competition for food at spring staging sites in the Baltic. According to an analytical model of optimal migration, the geese should skip the Baltic whenever the energy deposition rate falls below 88% of the Wadden Sea value.