Editor´s Choice - The exception to the rule: Bewick's swans migrate slower in spring than in autumn
Submitted by avianbiology on 14 March 2014.
A dominating pattern among migratory birds is that migration speed during spring exceeds that during autumn. This makes exceptions to this pattern particularly interesting. The fascinating study by Nuijten et al. compares migration speed of Bewick's swans during spring and autumn in relation the seasonal retreat and growth of the ice at stopover and breeding sites along the northern parts of its migration route.
The analysis is based on 15 complete annual GPS tracks of adult birds and the study convincingly shows that spring migration is slower than autumn migration. This indicates that the advance of the swans during spring is constrained by the melting ice, while the swans' autumn migration takes place well in advance of the ice formation. Thus, ice cover may constitute an important ecological constraint for migration speed among water and wetland birds in the Arctic.
Thomas Alerstam, Editor in Chief
You can access the abstract and link to the full text article here.
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