Previously‐used nesting cavities influence occurrence and territory size of Magellanic Woodpeckers.

SOTO, G.E., RODEWALD, A. D., VERGARA, P.M., OJEDA, V. AND CHAZARRETA, L

East Lansig

Congreso; American Ornithological Society (135th Stated Meeting) and Society of Canadian Ornithologists (35th Stated Meeting); 2017

Spatial configuration of resources directly affects occurrence and space use of organisms in ways that can affect long‐term population dynamics, especially when space for territories is limited. In this study we explored how clusters of cavities affected habitat use within territories of Magellanic Woodpeckers (Campephilus magellanicus), aterritorial resident that specializes on decayed wood within mature forests. As the primary cavity excavator of thetemperate South American forests, Magellanic woodpeckers roost, but rarely nest, in previously used cavities. We hypothesized that territory establishment depends both upon foraging habitat quality and availability of cavities on the landscape, as secondary cavity‐nester species are rarely reported using them. After the assessment of the spatial configuration of roosting sites (i.e., cavities), we used a Synoptic Model of Space Use to measure how the decay of trees and cavity availability changed occurrence within woodpecker territories which is inversely proportional to territory size. We used data from two study sites separated by 1500 km that represented northern and southernmost parts of their ~2300 km distribution. In both study areas tree decay was an important factor shaping occurrence probability within territories. However, space use models showed that spatial configuration of roosting cavities was strongly associated with occurrence of woodpeckers. Although we did not include agonistic behavior among territory holders, our results provide insight into the ways that resource availability and distribution can influence local population densities.