David M. Larson
There is widespread worry throughout the climate, ecology, and conservation fields about the species-level and ecosystem-level effects of anthropogenic climate change. For birds, two obvious problems are exposure to altered, higher temperatures at critical points in the life cycle and loss of the linkages between resource availability and breeding. Most importantly, strong selection pressure effects on breeding time, location, and success are expected during global and regional shifts in temperature and other habitat-critical climatic changes. Global temperatures have risen approximately 1oC during the last century. Long-term studies on bird populations seem best suited to sort out avian adaptations to such climatic shifts.
Birds can attempt to maintain their current maximum daily temperature in the face of climate warming by changing location to cooler places—moving their breeding territory to the north or to higher elevations—if they are trying to maintain optimal temperatures at the same breeding date. Alternatively, they can shift to earlier breeding times if they are trying to maintain optimal nesting temperature at the same location. Of course, they can do both to varying extent. If they cannot accommodate, they risk extinction.
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