Figure 2.

Rate of change in the date of spring arrival for 27 bird species at Powdermill Nature Reserve between 1961 and 2006 (filled square), and the rate of change expected if the entire response arose from individual-level plasticity induced by warming temperatures (open circles). Plasticity was estimated from a single hierarchical mixed-effect model conducted on the entire dataset (“pooled”), and from separate models for each species (“separate”). Temperature was averaged over southeastern North America. Error bars represent ± 95% CI.