Influences of Movement Behavior on Animal Distributions at Edges of Homogeneous Patches

Abstract

We propose that changes in movement behavior may be a proximate mechanism that in�uences the accumulation of animals at habitat edges. We tested this idea with a combination of empirical and simulation experiments in a resource-free landscape. e movements of individual �our beetles, Tribolium confusum, were tracked across a paper arena edged with invisible tape until beetles crossed the edge. Movement behavior (step lengths and turn angles) and cumulative occupancy were analyzed according to distance from the edge. We found that beetles took smaller steps with larger turn angles near edges than in the center of the arena and that beetle distribution was highly biased towards the edge of the arena. We then tested two agent-based simulation models for each beetle: an edge-independent model and an edge-dependent model. Both models predicted less time spent at the edge than was observed. e proportion of time spent at edges depended on the propensity to cross the edge, which could not be explained by beetle body size or energetic condition. e distribution of animals with respect to habitat edges depends on many factors, but we suggest that proximate mechanisms such as movement behavior should be explicitly considered when interpreting animal distributions.

Optimization of wrMTrck to monitor Drosophila larval locomotor activity

“…In addition, we have optimized tracking parameters to monitor the crawling behavior of adult Drosophila and Tribolium . This could be effective for tracking these insects under different conditions, such as the time required to navigate to a nutrient or odorant source, as movement behavior of individuals is a critical factor in the population ecology of Tribolium (Young et al, 2013). …”

The effect of sampling rate on observed statistics in a correlated random walk

“…To ensure the wide applicability of the present work, we consider the effect of the sampling rate on two quantities that are of fundamental interest in many such studies: the apparent speed of an individual between two consecutive observations and the apparent angle change (AAC) between three consecutive observations. These quantities have been used to elucidate the chemotactic response of the bacterium Rhodobacter sphaeroides [9] and the movement of beetles close to the boundaries of habitats [10]. Our work also applies to apparent displacement, since for a given sampling interval this quantity is linearly proportional to the apparent speed.…”