Effects of Land Cover on the Movement of Frugivorous Birds in a Heterogeneous Landscape

Abstract

Movement is a key spatiotemporal process that enables interactions between animals and other elements of nature. The understanding of animal trajectories and the mechanisms that influence them at the landscape level can yield insight into ecological processes and potential solutions to specific ecological problems. Based upon optimal foraging models and empirical evidence, we hypothesized that movement by thrushes is highly tortuous (low average movement speeds and homogeneous distribution of turning angles) inside forests, moderately tortuous in urban areas, which present intermediary levels of resources, and minimally tortuous (high movement speeds and turning angles next to 0 radians) in open matrix types (e.g., crops and pasture). We used data on the trajectories of two common thrush species (Turdus rufiventris and Turdus leucomelas) collected by radio telemetry in a fragmented region in Brazil. Using a maximum likelihood model selection approach we fit four probability distribution models to average speed data, considering short-tailed, long-tailed, and scale-free distributions (to represent different regimes of movement variation), and one distribution to relative angle data. Models included land cover type and distance from forest-matrix edges as explanatory variables. Speed was greater farther away from forest edges and increased faster inside forest habitat compared to urban and open matrices. However, turning angle was not influenced by land cover. Thrushes presented a very tortuous trajectory, with many displacements followed by turns near 180 degrees. Thrush trajectories resembled habitat and edge dependent, tortuous random walks, with a well-defined movement scale inside each land cover type. Although thrushes are habitat generalists, they showed a greater preference for forest edges, and thus may be considered edge specialists. Our results reinforce the importance of studying animal movement patterns in order to understand ecological processes such as seed dispersal in fragmented areas, where the percentage of remaining habitat is dwindling.

From ecology to remote sensing: using animals to map land cover

“…Our results extend on previous research on the link between animal behaviour and land cover taking a step further (Herremans ; Da Silveira et al., ; Brown et al. ).…”

“…However, while the relationship between movement and land cover has been roughly explored (Da Silveira et al. ; Brown et al. ; Rickbeil et al.…”

“…Behaviours such as resting and foraging have specific environmental requirements (P eron et al 2016;Abrahms et al 2017) that can potentially be translated into land cover classes. However, while the relationship between movement and land cover has been roughly explored (Da Silveira et al 2016;Brown et al 2017;Rickbeil et al 2017), this premise has not been tested for the purpose of land cover mapping.…”

Movement ecology of Afrotropical birds: Functional traits provide complementary insights to species identity

“…Other functional traits, such as dietary niche, dispersal ability and social structure, may also shape habitat use and movement behavior of species (Lundberg & Moberg, 2003). While many trait-based studies have described the correlates of species responses to land-use across large spatial scales (Bregman et al, 2016;Estrada et al, 2016;Newbold et al, 2013), few studies have assessed how habitat structures at a local scale may influence habitat use and movement behavior of bird species (Da Silveira, Niebuhr, de Lara Muylaert, Ribeiro, & Pizo, 2016).…”

Effects of forest fragmentation on biomass in tropical forests

“…Another prediction of the "landscape conceptual model" is that matrix type can mediate, by different mechanisms, the effects of patch size and edges on biomass. First, biological flux can be facilitated or limited depending on the degree of matrix permeability (Antongiovanni & Metzger, 2005;Da Silveira et al, 2016). Second, the magnitude and extension of edge effects can be influenced by the surrounding matrix (Tabarelli & Gascon, 2005; through the degree of structural difference among the habitat patch and the matrix Prevedello & Vieira, 2010).…”