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Abstract
In recent decades, red wolf (Canis rufus) hybridization with coyotes (Canis latrans) has posed a serious threat to red wolf recovery efforts. Preventing hybridization has become a primary objective requiring intensive management efforts to prevent introgression. As the red wolf population increases, long-term recovery requires general understanding of red wolf and coyote ecology to develop appropriate management strategies for addressing hybridization. The primary objective of this study was to understand the underlying mechanisms that influence red wolf and coyote interactions by examining morphology, diet, and spatial ecology of both species. We examined external morphological characters of red wolves, coyotes, and their hybrids to determine if morphology could be an accurate discriminator among the 3 canid taxa. Using hind foot length, weight, width of head, and tail length, we were able to correctly identify 86% of canids to their a priori species groups as identified via genetic analysis. We also assessed factors affecting prey selection of red wolf packs, coyote pairs, and congeneric pairs of red wolves and coyotes and found that all three had similar and overlapping diets. Nevertheless, we detected differential use of prey; difference in diet was associated with body size. Larger individuals within and among different breeding pairs consumed more white-tailed deer, and less rabbits and small mammals. We observed red wolf and coyote preferences for agricultural habitats over forested habitats and space use patterns to be influenced by body size. Coyote home-ranges had an upper limit of approximately 50 km^2, whereas an upper limit for red wolves was approximately 180 km^2. Home-ranges of congeneric pairs did not exceed 50 km^2 and we suggest the smaller coyote may constrain and limit space use patterns of congeneric pairs. We suggest that similarities in body size of individual red wolves and coyotes may contribute to successful congeneric pairing and hybridization via similar use of space, habitat, and prey. Therefore, lowering hybridization rates between red wolves and coyotes may require increasing the average body size of the red wolf population to facilitate differential use of limiting resources.