Population vulnerability to climate change linked to timing of breeding in boreal ducks / Mark C. Drever, Robert G. Clark, Chris Derksen, Stuart M. Slattery, Peter Toose, and Thomas D. Nudds.

Includes bibliographical references (pages 490-492).

Identifying and understanding why traits make species vulnerable to changing climatic conditions remain central
problems in evolutionary and applied ecology. We used spring snow cover duration as a proxy for phenological timing
of wetland ecosystems, and examined how snow cover duration during spring and during the entire snow season
affected population dynamics of duck species breeding in the western boreal forest of North America, 1973–2007. We
predicted that population level responses would differ among duck species, such that late-nesting species with
reduced flexibility in their timing of breeding, i.e. scaup (Aythya spp.) and scoter (Melanitta spp.), would be more
strongly affected by changing snow cover conditions relative to species better able to adjust timing of breeding to seasonal
phenology, i.e. mallard (Anas platyrhynchos) and American wigeon (Anas americana). Population growth rates of
scaup and scoter were positively linked to spring snow cover duration; after accounting for effects of density dependence,
larger populations resulted after springs with long snow cover duration than after springs with short snow
cover duration. In contrast, population growth rates of mallard and wigeon were either negatively or only weakly
associated with snow cover duration. Duck population models were then incorporated with snow cover duration
derived from climate model simulations under the A2 emission scenario, and these predictions suggested that latenesting
duck species will experience the most severe population declines. Results are consistent with a hypothesis
that the gradual climatic warming observed in the western boreal forest of North America has contributed to and
may continue to exacerbate population declines of scaup and scoter.