Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds

Abstract

1. Anthropogenic actions cause rapid ecological changes, meaning that animals have to respond before they have time to adapt. Tools to quantify emergent spatial patterns from animal-habitat interaction mechanisms are vital for predicting the population-level effects of such changes. 2. Environmental perturbations are particularly prevalent in the Amazon rainforest, and have a profound effect on fragmentation-sensitive insectivorous bird flocks. Therefore it is important to be able to predict the effects of such changes on the flocks' space-use patterns. 3. We use a step selection function (SSF) approach to uncover environmental drivers behind movement choices. This is used to construct a mechanistic model, from which we derive predicted utilization distributions (home ranges) of flocks. 4. We show that movement decisions are significantly influenced by canopy height and topography, but not resource depletion and renewal. We quantify the magnitude of these effects and demonstrate that they are helpful for understanding various heterogeneous aspects of space use. We compare our results to recent analytic derivations of space use, demonstrating that they are only accurate when assuming that there is no persistence in the animals' movement. 5. Our model can be translated into other environments or hypothetical scenarios, such as those given by proposed future anthropogenic actions, to make predictions of spatial patterns in bird flocks. Furthermore, our approach is quite general, so could be used to predict the effects of habitat changes on spatial patterns for a wide variety of animal communities.