Data from: Environmental heterogeneity decreases reproductive success via effects on foraging behaviour

Environmental heterogeneity shapes the uneven distribution of resources
available to foragers, and is ubiquitous in nature. Optimal foraging
theory predicts that an animal’s ability to exploit resource patches is
key to foraging success. However, the potential fitness costs and benefits
of foraging in a heterogeneous environment are difficult to measure
empirically. Heterogeneity may provide higher quality foraging
opportunities, or alternatively could increase the cost of resource
acquisition because of reduced patch density or increased competition.
Here, we study the influence of physical environmental heterogeneity on
behaviour and reproductive success of black-legged kittiwakes, Rissa
tridactyla. From GPS tracking data at 15 colonies throughout their British
and Irish breeding range, we found that environments that were physically
more heterogeneous were associated with longer trip duration, more time
spent actively foraging whilst away from the colony, increased overlap of
foraging areas between individuals, and lower breeding success. These
results suggest that in more heterogeneous environments, there is greater
competition between individuals for finite resources, which comes at a
cost to reproduction. Resource hotspots are often considered to be
beneficial, as individuals can learn to exploit them if sufficiently
predictable. However, we demonstrate here that such fitness gains can be
countered by greater competition in more heterogeneous environments.