Data from: Food supplementation mitigates dispersal-dependent differences in nest defence in a passerine bird.

Dispersing and non-dispersing individuals often differ in phenotypic
traits (e.g. physiology, behaviour), but to what extent these differences
are fixed or driven by external conditions remains elusive. We
experimentally tested whether differences in nest-defence behaviour
between dispersing and non-dispersing individuals changed with local
habitat quality in collared flycatchers, by providing additional food
during the nestling rearing period. In control (non-food-supplemented)
nests, dispersers were less prone to defend their brood compared with
non-dispersers, whereas in food-supplemented nests, dispersing and
non-dispersing individuals showed equally strong nest defence. We discuss
the importance of dispersal costs versus adaptive flexibility in
reproductive investment in shaping these differences in nest-defence
behaviour between dispersing and non-dispersing individuals. Irrespective
of the underlying mechanisms, our study emphasizes the importance of
accounting for environmental effects when comparing traits between
dispersing and non-dispersing individuals, and in turn assessing the costs
and benefits of dispersal.