MISSING THE SMALL PICTURE: MAPPING GEOGRAPHIC-DEPENDENCY IN THE RELATIONSHIP BETWEEN A THREATENED WOODPECKER AND ITS COMPETITOR
The ongoing population declines of Red-headed Woodpeckers (Melanerpes erythrocephalus), a threatened species in Canada in several states in the U.S., are poorly understood. Our research at the northern edge of the species’ range revealed that the abundance of the non-native, interference competitor European Starling (Sturnus vulgaris) at Red-headed Woodpecker nest sites is the dominant factor driving lower nest survival for the species. Our findings contradict those from previous studies, suggesting that interference competition between the two species may be spatially and/or temporally variable. We hypothesize that such a spatially variable relationship would be ill suited for the typical global comparisons used for ecological data, for although these models are useful for their predictive abilities, their findings may be inaccurate when applied to spatially variable data. Instead, we explore the use of a spatially explicit technique, geographically weighted regression, capable of interpreting the non-stationarity often found in ecological relationships. Using Breeding Bird Survey data from 1966-2011, divided into four time periods, we demonstrate high spatial autocorrelation, non-stationarity, and low model fit for comparisons of Red-headed Woodpecker vs. European Starling abundances in global models. Using geographically weighted regression, we exponentially increase model fit and demonstrate heterogeneity across time and space in the relationships between the two species, providing insight into the population dynamics of these important organisms whose life histories are often interconnected. We suggest that the mapping of the model interaction in geographically weighed regression may be a useful tool to illustrate research potential and customize management goals across a species’ range.
Frei, B., University of Ottawa & McGill University, Canada, email@example.com
Fyles, J. W., McGill University, Canada, firstname.lastname@example.org
Cardille, J. A., McGill University, Canada, email@example.com
Nocera, J. J., Trent University , Canada, firstname.lastname@example.org
Location: Emerald Mountain - Bible Point
Presentation is given by student: No