Mechanistic home range analysis reveals drivers of space use patterns for a non-territorial passerine.

Natasha Ellison,Clare J Napper,Jonathan R Potts,Sarah J Biddiscombe,Ben J Hatchwell,Annette Fayet

doi:10.1111/1365-2656.13292

Abstract

Home ranging is a near-ubiquitous phenomenon in the animal kingdom. Understanding the behavioural mechanisms that give rise to observed home range patterns is thus an important general question, and mechanistic home range analysis (MHRA) provides the tools to address it. However, such analysis has hitherto been principally restricted to scent-marking territorial animals, so its potential breadth of application has not been tested. Here, we apply MHRA to a population of long-tailed tits Aegithalos caudatus, a non-territorial passerine, in the non-breeding season where there is no clear 'central place' near which birds need to remain. The aim is to uncover the principal movement mechanisms underlying observed home range formation. Our foundational models consist of memory-mediated conspecific avoidance between flocks, combined with attraction to woodland. These are then modified to incorporate the effects of flock size and relatedness (i.e. kinship), to uncover the effect of these on the mechanisms of home range formation. We found that a simple model of spatial avoidance, together with attraction to the central parts of woodland areas, accurately captures long-tailed tit home range patterns. Refining these models further, we show that the magnitude of spatial avoidance by a flock is negatively correlated to both the relative size of the flock (compared to its neighbour) and the relatedness of the flock with its neighbour. Our study applies MHRA beyond the confines of scent-marking, territorial animals, so paves the way for much broader taxonomic application. These could potentially help uncover general properties underlying the emergence of animal space use patterns. This is also the first study to apply MHRA to questions of relatedness and flock size, thus broadening the potential possible applications of this suite of analytic techniques.

Highlights

Our foundational models consist of memory-mediated conspecific avoidance between f ocks combined with attraction to wood and These are modified to incorporate the effects of f ock size and re atedness i e kinship to uncover the effect of these on the mechanisms of home range formation
Understanding the spatial distributions of animals is a core concern for eco ogica research being at the interface of popu ation dynamics behavioura eco ogy and conservation concerns Frank in whi e emergent patterns of space use may be observed broad y across time and space they are u timate y caused by movement decisions of individua anima s Nathan et a
4 in capturing the home range patterns. These results indicate that two aspects of movement responses to habitat and conspecifics combine to give the key ingredients in the formation of long-tailed tit home ranges

Summary

| INTRODUCTION

This has ed to the hypothesis that there may be general mechanisms underlying home range formation that operate across many species B rger et a a though the mechanisms involved have proved rather elusive. Mc ough in Ferguson Messier and hierarchies of size and socia dominance H jesj Øk and Sundstr m Principa y those which seek to unvei the movement and interaction processes that give rise to home range pattern formation require a mechanistic mode ing approach In such an approach the proximate behavioura decisions of an anima i e processes are mode ed exp icit y and the home range i e pattern arises as an emergent property of this model. In this study we advance the app icabi ity of PDE based MHRA further sti by showing that MHRA can be used in situations where there is no exp icit territoria behaviour and a so no centra point around which animals localize their movement This is the case for our study species the ong tai ed tit Aegithalos caudatus outside the breeding season At these times of year they ive in f ocks each of which has a distinct home range that only overlaps slightly with those of neighbouring f ocks Gaston. Overa our study makes theoretica advances by demonstrating a that MHRA is app icab e in a much wider range of situations than previous y used and b that MHRA can uncover behavioura drivers of movement and space use that are not simp e to find using traditiona statistica measures of home range our study makes important advances in avian behavioura eco ogy by demonstrating c that relatedness and flock size can affect between-flock movement responses and d that avoidance mechanisms may exist in species that do not disp ay obvious territoria behaviour exp aining the existence of home range segregation in such species

| MATERIALS AND METHODS

| RESULTS

| DISCUSSION

E E McGreer M T Fryxe J M

E H Ray N D Murray D L

E Weimerskirch H