13 May 2016
Vol 352, Issue 6287

About The Cover

Cover image expansion

COVER Red knots (Calidris canutus canutus) migrate between the high Arctic, where they breed during summer, and the West African tropics. Chicks born under rapidly warming conditions in the Arctic attain smaller sizes before migrating, and the shorter bills of these smaller birds hamper their ability to reach food on the wintering grounds. Similar warming-induced morphological changes with downstream survival effects may also extend to other Arctic migrants. See pages 775 and 819.
Photo: Jan van de Kam