Large-scale supplemental feeding alters lay date and nest survival in Eastern Bluebirds but not in two species of chickadees

Wild bird feeding is a popular and growing activity, with approximately half of households participating in nations including the United States, Canada, the United Kingdom, New Zealand, and Australia. Supplemental feeding can increase survival and reproductive success of birds (which is often a goal of supplemental feeding efforts), but it raises concerns about phenological mismatch, reduced clutch size, or increased risk of nest predation. Our objectives were to test whether access to supplemental food during the breeding season was correlated with (1) advanced egg-laying phenology, (2) increased clutch size, or (3) improved nest survival of 3 cavity-nesting species (Carolina Chickadee, Poecile carolinensis; Black-capped Chickadee, P. atricapillus; and Eastern Bluebird, Sialia sialis) at a large spatial scale (United States and Canada; 22 degrees latitude difference and 55 degrees longitude difference). We examined data from 24,528 nest attempts submitted to NestWatch from 2014–2019. F...