The effects of spatially heterogeneous prey distributions on detection patterns in foraging seabirds

TL;DR

This study investigates how the spatial heterogeneity of prey affects detection patterns in foraging seabirds, revealing that prey distribution structure influences detection intervals more than foraging strategy, with implications for understanding animal foraging behavior.

Contribution

The paper demonstrates that prey spatial structure primarily determines detection patterns, distinguishing between uniform and fractal prey fields, and supports models with empirical seabird data.

Findings

Detection intervals are Poissonian in uniform prey environments.

Fractal prey fields induce non-Poissonian detection patterns.

Detection patterns are driven by landscape structure, not forager strategy.

Abstract

Many attempts to relate animal foraging patterns to landscape heterogeneity are focused on the analysis of foragers movements. Resource detection patterns in space and time are not commonly studied, yet they are tightly coupled to landscape properties and add relevant information on foraging behavior. By exploring simple foraging models in unpredictable environments we show that the distribution of intervals between detected prey (detection statistics)is mostly determined by the spatial structure of the prey field and essentially distinct from predator displacement statistics. Detections are expected to be Poissonian in uniform random environments for markedly different foraging movements (e.g. L\'evy and ballistic). This prediction is supported by data on the time intervals between diving events on short-range foraging seabirds such as the thick-billed murre ({\it Uria lomvia}). However, Poissonian detection statistics is not observed in long-range seabirds such as the wandering albatross ({\it Diomedea exulans}) due to the fractal nature of the prey field, covering a wide range of spatial scales. For this scenario, models of fractal prey fields induce non-Poissonian patterns of detection in good agreement with two albatross data sets. We find that the specific shape of the distribution of time intervals between prey detection is mainly driven by meso and submeso-scale landscape structures and depends little on the forager strategy or behavioral responses.