Print PageWhite-tailed deer are moderately social, with females and their recent offspring forming matrilineal groups. However, recent genetic and behavioral analyses suggest that group membership may be more fluid than previously realized. We analyzed GPS-collar data from 44 does and 2 male fawns from 2 study sites near Carbondale and Lake Shelbyville, Illinois, 2002 to 2009. Collars recorded locations of individual deer every 1-2 hours for 1-17 months. We quantified and characterized the social affinities of pairs of deer over various time scales, by the proximity of simultaneous GPS locations of deer in a pair and the correlation of their movements. We incorporated the apparent patterns into a simple individual-based model of direct disease transmission to examine whether fine-scale social information is necessary to infer disease patterns.
Results/Conclusions
Some pairs exhibited tenacious affinity, consistently remaining <100 m apart with highly correlated movements except for ca. 1 month during fawning season. However, even these pairs separated briefly by >500 m as frequently as every week. Other pairs moved independently and rarely approached within 100 m. Several pairs exhibited intermediate social affinities, moving independently much of the time but with frequent bouts in which they moved in close proximity for hours to days before separating again. Some pairs with high affinity in one year were much more independent the next, and other pairs exhibited the opposite pattern. Our results highlight the fluidity of white-tailed deer social structure, and suggest that female deer frequently associate with their neighbors, albeit for short periods. This social fluidity contrasts with more rigid social structures observed in low-mortality deer populations, and may enhance opportunities for disease transmission among deer. Our simulation modeling implies that failing to account for brief social interactions can lead to an underestimate of the potential transmission between neighboring groups.
