Table 1.

Mixed-effect linear models estimating temperature-induced plasticity in arrival date of birds sampled at Powdermill Nature Reserve in western Pennsylvania, USA. The response variable is arrival date. The table reports coefficients for fixed effects and variance components for random effects. Boldface highlights estimates that were significant. Arrival date was measured in days, age in years, and temperature in °C. The range of dates over which temperature was averaged was 1 March until 20 May. Individual was nested within species. Sample size was 5988 observations from 2441 individuals of 27 species

Source	Level	Estimate	SE	P-value
Fixed effects (coefficients)
Age		−1.721	0.162	0.0001
Migration distance	Long	22.712	3.790	0.0001
Temperature		−1.558	0.407	0.0001
Migr dist × temperature	Long	1.258	0.633	0.0469
Random effects (variance components)
Species		92.656	.	0.0001
Species × temperature		0	.	.
Individual		38.913	.	0.0001
Individual × temperature		0	.