The Effects of Spatially Heterogeneous Prey Distributions on Detection Patterns in Foraging Seabirds

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. Lévy 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 ( Uria lomvia ). However, Poissonian detection statistics is not observed in long-range seabirds such as the wandering albatross ( 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.

Scaling laws of ambush predator ‘waiting’ behaviour are tuned to a common ecology

“…The average scaling exponent (m) for individual predators was not different in the wild compared with in captivity (mean exponent: wild, m ¼ [7,26,36]), as has been proposed for foragers in other systems [35,37]. Therefore, it is possible that scaling in waiting times is a general behaviour pattern that improves the chances of foraging success [28] and has naturally evolved.…”

Detection of Rare Antigen-Presenting Cells through T Cell-Intrinsic Meandering Motility, Mediated by Myo1g

“…Search is a feature of many biological systems and it is well understood that ballistic modes of predatory searching, as by some sea birds, produces a search that is significantly incomplete (Miramontes et al, 2012). The phenotype of Myo1g−/− T cells and the modeling of their “Search” versus “Evaluation” dynamics provide an enlarged framework for additional understanding of immune search and surveillance.…”

Optimal foraging strategies: Lévy walks balance searching and patch exploitation under a very broad range of conditions

“…The Lévy prey field was constructed with the first patch being positioned using uniform random numbers for the x and y coordinates and subsequent patches then located relative to the first patch by calculating a vector (from a truncated Pareto distribution, with parameters x min = 25, µ = 2.0, x max = 5000) and a uniform turning angle; periodic boundary conditions were observed. The resulting pattern has been referred to as a Lévy 'dust' (Miramontes et al, 2012). Details of all prey field distributions are given in Table 1; the abundant 1, Lévy prey field is illustrated in Figure 1.…”