Data from: Experimental food supplementation reveals habitat-dependent male reproductive investment in a migratory bird

Environmental factors can shape reproductive investment strategies and
influence the variance in male mating success. Environmental effects on
extrapair paternity have traditionally been ascribed to aspects of the
social environment, such as breeding density and synchrony. However,
social factors are often confounded with habitat quality and are
challenging to disentangle. We used both natural variation in habitat
quality and a food supplementation experiment to separate the effects of
food availability—one key aspect of habitat quality—on extrapair paternity
(EPP) and reproductive success in the black-throated blue warbler,
Setophaga caerulescens. High natural food availability was associated with
higher within-pair paternity (WPP) and fledging two broods late in the
breeding season, but lower EPP. Food-supplemented males had higher WPP
leading to higher reproductive success relative to controls, and when in
low-quality habitat, food-supplemented males were more likely to fledge
two broods but less likely to gain EPP. Our results demonstrate that food
availability affects trade-offs in reproductive activities. When food
constraints are reduced, males invest in WPP at the expense of EPP. These
findings imply that environmental change could alter how individuals
allocate their resources and affect the selective environment that drives
variation in male mating success.