PT  - JOURNAL ARTICLE
AU  - Brian C. Weeks
AU  - David E. Willard
AU  - Aspen A. Ellis
AU  - Max L. Witynski
AU  - Mary Hennen
AU  - Benjamin M. Winger
TI  - Shared morphological consequences of global warming in North American migratory birds
AID  - 10.1101/610329
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 610329
4099  - http://biorxiv.org/content/early/2019/04/18/610329.short
4100  - http://biorxiv.org/content/early/2019/04/18/610329.full
AB  - Increasing temperatures associated with climate change are predicted to cause reductions in body size, a key determinant of animal physiology and ecology. Using a four-decade specimen series of 70,716 individuals of 52 North American migratory bird species, we demonstrate that increasing annual summer temperature over the 40-year period drove consistent reductions in body size across these diverse taxa. Concurrently, wing length – which impacts nearly all aspects of avian ecology and behavior – has consistently increased across taxa. Our findings suggest that warming-induced body size reduction is a general response to climate change, and reveal a similarly consistent shift in an ecologically-important dimension of body shape. We hypothesize that increasing wing length represents a compensatory adaptation to maintain migration as reductions in body size have increased the metabolic cost of flight. An improved understanding of warming-induced morphological changes, and their limits, are important for predicting biotic responses to global change.