Large birds travel farther in homogeneous environments
Authors: Tucker Marlee A. , Alexandrou Olga , Bierregaard Richard O. , Bildstein Keith L. , Böhning‐Gaese Katrin , Bracis Chloe , Brzorad John N. , Buechley Evan R. , Cabot David , Calabrese Justin M. , Carrapato Carlos , Chiaradia Andre , Davenport Lisa C. , Davidson Sarah C. , Desholm Mark , DeSorbo Christopher R. , Domenech Robert , Enggist Peter , Fagan William F. , Farwig Nina , Fiedler Wolfgang , Fleming Christen H. , Franke Alastair , Fryxell John M. , García‐Ripollés Clara , Grémillet David , Griffin Larry R. , Harel Roi , Kane Adam , Kays Roland , Kleyheeg Erik , Lacy Anne E. , LaPoint Scott , Limiñana Rubén , López‐López Pascual , Maccarone Alan D. , Mellone Ugo , Mojica Elizabeth K. , Nathan Ran , Newman Scott H. , Noonan Michael J. , Oppel Steffen , Prostor Mark , Rees Eileen C. , Ropert‐Coudert Yan , Rösner Sascha , Sapir Nir , Schabo Dana , Schmidt Matthias , Schulz Holger , Shariati Mitra , Shreading Adam , Paulo Silva João , Skov Henrik , Spiegel Orr , Takekawa John Y. , Teitelbaum Claire S. , van Toor Mariëlle L. , Urios Vicente , Vidal‐Mateo Javier , Wang Qiang , Watts Bryan D. , Wikelski Martin , Wolter Kerri , Žydelis Ramūnas , Mueller Thomas 
Published: January 2019

Aim

Animal movement is an important determinant of individual survival, population dynamics and ecosystem structure and function. Nonetheless, it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside the migratory period, we examined how the distribution of resources affects the movement patterns of both large terrestrial birds (e.g., raptors, bustards and hornbills) and waterbirds (e.g., cranes, storks, ducks, geese and flamingos).

Location

Global.

Time period

2003–2015.

Major taxa studied

Birds.

Methods

We compiled GPS tracking data for 386 individuals across 36 bird species. We calculated the straight‐line distance between GPS locations of each individual at the 1‐hr and 10‐day time‐scales. For each individual and time‐scale, we calculated the median and 0.95 quantile of displacement. We used linear mixed‐effects models to examine the effect of the spatial arrangement of resources, measured as enhanced vegetation index homogeneity, on avian movements, while accounting for mean resource availability, body mass, diet, flight type, migratory status and taxonomy and spatial autocorrelation.

Results

We found a significant effect of resource spatial arrangement at the 1‐hr and 10‐day time‐scales. On average, individual movements were seven times longer in environments with homogeneously distributed resources compared with areas of low resource homogeneity. Contrary to previous work, we found no significant effect of resource availability, diet, flight type, migratory status or body mass on the non‐migratory movements of birds.

Main conclusions

We suggest that longer movements in homogeneous environments might reflect the need for different habitat types associated with foraging and reproduction. This highlights the importance of landscape complementarity, where habitat patches within a landscape include a range of different, yet complementary resources. As habitat homogenization increases, it might force birds to travel increasingly longer distances to meet their diverse needs.