Abstract
Predation risk is vital in determining habitat quality. But landscapes of fear are complex and dynamic, such as temperate deciduous forests characterized by intermittent, synchronized production of large seed crops (mast peaks). These “resource pulses” elevate the magnitude of predation risk via direct or indirect effects, possibly altering also predator avoidance strategies of a prey. Yet, how animals manage predation risk via informed habitat selection and how this depends on ecological context remains poorly explored. We studied risk-sensitive settlement behavior of wood warbler Phylloscopus sibilatrix. We tested the hypothesis that warblers flexibly avoid predators (Eurasian jays Garrulus glandarius) during habitat selection but that their interactions are mediated by mast seeding, which is known to elevate the overall nest predation risk for warblers through its cascading effects on population dynamics of rodents and generalist predators. We used a playback experiment to manipulate warblers’ perceived risk of nest predation by jays. We replicated the experiment in two consecutive years, followed by high or low seed crop. In the spring following mast trough, risky jay plots featured low abundance, late settlement, and poor pairing success compared to other treatments. In contrast, no response differences were found in the spring following mast seeding. Our results suggest that the way wood warblers adjust habitat choices to jay predation risk is indirectly mediated by mast seeding. This highlights plasticity in predator avoidance during prey habitat selection in complex and dynamic landscapes of fear, and the potential effects of mast seeding on animal behavior via indirect interactions.Significance statementAvoiding places with high nest predation risk during settlement decisions is believed to be widespread in birds. However, the mechanistic understanding of how birds acquire and use information about ambient nest predation risk to fine-tune settlement decisions is still limited. Using a playback experiment, we show that wood warblers eavesdrop on predator calls and avoid settling at sites with high perceived risk of nest predation by Eurasian jays. However, the way warblers adjust habitat choices to the nest predation risk posed by jays appears to be affected by tree mast seeding. This is potentially due to cascading effects of masting on the population dynamics of rodents and generalist predators, creating temporal peaks of elevated nest predation risk for wood warblers. Our study highlights plasticity in predator avoidance during prey settlement behavior in temporally variable, pulsed-resources ecosystems.
Highlights
Many animals are temporally bound to a specific location—a territory, in which a nest is placed and offspring are raised
Between-year differences in habitat selection responses of wood warblers to simulated presence of jays could not be attributed to variation in abundance of naturally occurring jays
Male wood warblers adjusted fine-scale territory spacing to the perceived risk of nest predation by jays and consistently increased the distance between the putative location of a nest predator and their own territories
Summary
Many animals are temporally bound to a specific location—a territory, in which a nest is placed and offspring are raised. These breeding site–selection decisions have far-reaching consequences for survival and reproductive success (Cody 1985; Fuller 2012). Behav Ecol Sociobiol (2019) 73: 91 heterogeneity in environmental conditions. This uncertainty can be reduced by gathering information about ambient conditions prior to making a territory choice (Dall et al 2005; Seppänen et al 2007; Schmidt et al 2010; Szymkowiak 2013). Information gathering and use provides a selective advantage that facilitates decision-making and allows for better choices, and is at the core of animal–environment interactions. Examining how animals use various cues for settlement decisions is needed for understanding complex habitat selection strategies
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