Consequences of information use in breeding habitat selection on the evolution of settlement time

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Abstract

The role of temporal changes and spatial variability in predation risk and prey's means of mitigating such risks is poorly understood in the context of potential threats of global climate change for migratory birds. Yet nest predation, for example, represents a primary source of reproductive mortality in birds. To assess risk birds must spend time prospecting potential breeding sites for cues or signals of predator presence. However, competition for breeding sites with advantage to prior residency poses an evolutionary dilemma as individuals also benefit from early settling. We develop a model to examine adaptive prospecting time for predator cues on breeding grounds characterized by spatial heterogeneity in nest predation risk. We study how populations respond to environmental change represented by variation in habitat specific levels of nest predation, habitat composition, population vital rates, and availability of information (via prospecting) in the form of acoustic predator cues. We identify two mechanisms that regulate and buffer impacts of environmental change on populations. First, the adaptive response to lower population abundance under deteriorating environmental conditions is to increase prospecting time, which in turn increases individuals nest success to counteract population declines. This occurs because reduced competition for sites decreases the benefit of early settlement. Second, per capita success in site choice increases during population declines owing to reduced competition that increases the availability of good sites. We also show that the increased benefit to settling early when competition increases can lead to the paradoxical result that with greater spatial heterogeneity, less effort is placed on discerning good and bad sites. Our analysis thus contributes several novel results by which nest predation, settlement phenology, prospecting time and information gathering can influence species capacity to adapt to changing environments.

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