The impacts of climate change on the annual cycles of birds

摘要

Organisms living today are descended from ancestors that experienced considerable climate changein the past. However, they are currently presented with many new, man-made challenges, includingrapid climate change. Migration and reproduction of many avian species are controlled by endogen-ous mechanisms that have been under intense selection over time to ensure that arrival to anddeparture from breeding grounds is synchronized with moderate temperatures, peak food avail-ability and availability of nesting sites. The timing of egg laying is determined, usually by bothendogenous clocks and local factors, so that food availability is near optimal for raising young.Climate change is causing mismatches in food supplies, snow cover and other factors that couldseverely impact successful migration and reproduction of avian populations unless they are ableto adjust to new conditions. Resident (non-migratory) birds also face challenges if precipitationand/or temperature patterns vary in ways that result in mismatches of food and breeding. Predic-tions that many existing climates will disappear and novel climates will appear in the futuresuggest that communities will be dramatically restructured by extinctions and changes in range dis-tributions. Species that persist into future climates may be able to do so in part owing to the geneticheritage passed down from ancestors who survived climate changes in the past.