Endozoochory by white-tailed deer (Odocoileus virginianus) across a suburban/woodland interface

We examined the role of white-tailed deer (Odocoileus virginianus) in the dispersal of viable seeds in an intact forest bordered by medium-density housing in southern Connecticut. Estimated deer density on site was 23 deer/km(2) with higher local densities along the suburban/woodland interface. A total of 566 pellet groups were gathered in summers through early winters of 2002-2005. After vernalization at 5 degrees C for 60 days, pellet groups were placed in a growing medium in a temperature controlled greenhouse for 6 months. A total of 11,512 seedlings germinated from 61% of pellet groups, which included 86 taxa. Seeds of 40 species confirmed not native to the United States germinated from pellet groups. Given mean germination data of more than 20 germinants/pellet group and deer population estimate, each deer on site during the sampling interval had the potential to disperse over 500 viable seeds/day, which included approximately 350 seeds of exotic species. Median maximum travel distance of does for a 24-h period was 568 m with a maximum distance of 5932 m. Deer were likely consuming seeds in disturbed and/or edge habitats, which are often adjacent to residential housing, and transporting them into forested areas where exotic plants are not as prevalent. Birds, small mammals, and abiotic factors are known dispersal agents for plants. These results indicate that white-tailed deer are another important dispersal agent of seeds, particularly exotics. Thus, white-tailed deer may not only alter vegetation structure through direct browse damage of established plants, but also indirectly by lowering reproductive output of native plants and simultaneously distributing seeds of exotic species. (C) 2007 Published by Elsevier B.V.