Does movement behaviour predict population densities? A test with 25 butterfly species. (4th January 2017)

• Record Type: Journal Article
• Authors: Schultz, Cheryl B.; Pe'er, B. Guy; Damiani, Christine; Brown, Leone; Crone, Elizabeth E.
• Editors: Lele, Subhash
• Is Part Of: Journal of animal ecology. Volume 86:Number 2(2017:Mar.)
• Page Start: 384
• Page End: 393
• Publication Date: 2017-01-04
• Subjects: butterflies -- correlated random walk -- diffusion -- dispersal -- expected net squared displacement -- movement ecology; Animal ecology -- Periodicals; 591.7
• DOI: 10.1111/1365-2656.12609
• Languages: English
• ISSNs: 0021-8790

Abstract

Summary: Diffusion, which approximates a correlated random walk, has been used by ecologists to describe movement, and forms the basis for many theoretical models. However, it is often criticized as too simple a model to describe animal movement in real populations. We test a key prediction of diffusion models, namely, that animals should be more abundant in land cover classes through which they move more slowly. This relationship between density and diffusion has rarely been tested across multiple species within a given landscape. We estimated diffusion rates and corresponding densities of 25 Israeli butterfly species from flight path data and visual surveys. The data were collected across 19 sites in heterogeneous landscapes with four land cover classes: semi‐natural habitat, olive groves, wheat fields and field margins. As expected from theory, species tended to have higher densities in land cover classes through which they moved more slowly and lower densities in land cover classes through which they moved more quickly. Two components of movement (move length and turning angle) were not associated with density, nor was expected net squared displacement. Move time, however, was associated with density, and animals spent more time per move step in areas with higher density. The broad association we document between movement behaviour and density suggests that diffusion is a good first approximation of movement in butterflies. Moreover, our analyses demonstrate that dispersal is not a species‐invariant trait, but rather one that depends on landscape context. Thus, land cover classes with high diffusion rates are likely to have low densities and be effective conduits for movement. Abstract : In accordance with general theory, diffusion predicted density for 25 butterfly species across 4 land cover types. Movement and dispersal may depend on landscape context more than species identity, and areas with high diffusion and low densities may be effective conduits for movement.