Fig. 5: Breeding timing, temperature exposure, and extreme temperature sensitivity in eastern bluebirds.
From: Inconsistent shifts in warming and temperature variability are linked to reduced avian fitness
A Average date of first egg laying across the records included. B Distribution of the coldest and hottest 3-day high temperatures in the full nesting cycles in five latitude bands with an equal number of samples per band. The top of the panel is the northernmost band and bottom is the southernmost. Boxplots indicate median, IQR, and 1.5 times IQR for the coldest (blue) and hottest (red) 3-day period. C, D Predicted relative fitness for breeding attempts that experienced a 2 SD cold snap (blue) or 2 SD heatwave (red) during incubation (C) or provisioning (D) for each latitude band. Point estimates are derived from GAMs that control for spatial patterns, year, and date. Circles show point estimate, lines show 95 percent CI; open circles indicate no difference from mean reproductive success while closed circles indicate a significant effect of temperature on relative reproductive success. In panels B and C, the number of nests used to derive estimates from northernmost to southernmost latitude bands was 9254, 9897, 10589, 11363, and 12321, respectively. In panel D, the number of nests included was 8035, 8657, 9244, 9990, and 10662, respectively. Illustration from Handbook of the Birds of the World by Ian Willis, copyright Lynx Edicions.
