Deer Rapidly Spread Invasive Plants
A surprisingly large quantity and variety of plant seeds are getting carried substantial distances by white-tailed deer.
Findings from two independent studies in eastern United States suggest that deer are facilitating the swift spread of invasive plants.
Deer consume seeds while browsing and then deposit the seeds elsewhere in a pile of droppings, a mechanism of seed dispersal that biologists term endozoochory. Researchers found that even though seeds have passed through the gut of a deer, typically 20 or 30 seedlings can germinate from one manure mound. This implies that a white-tailed deer scatters over 500 viable seeds daily.
It turns out that the deer have wide-ranging culinary tastes. Researchers sprouted 70 different plant species from deer dung picked up in central New York State. They grew herbs, shrubs and trees that originated from all different kinds of habitat. Similarly, a southern Connecticut study germinated 86 species of plants from seeds found in deer pellets.
White-tailed deer also aren't afraid to sample new foods. The New York seedlings included several exotic and invasive species. Deer in Connecticut were carrying 40 species of plants not native to United States.
The studies shed light on how invasive plants migrate so quickly to new areas once reaching the North American continent. In Connecticut, seed-dispersing deer often travel over one-third of a mile, and as far as 3.7 miles (5.9 kilometres), in a single day.
Jonathan A. Myers, Mark Vellend, Sana Gardescu and P.L. Marks. 2004. Seed dispersal by white-tailed deer: implications for long-distance dispersal, invasion, and migration of plants in eastern North America. Oecologia. 139(1): 35-44.
Scott C. Williams, Jeffrey S. Ward and Uma Ramakrishnan. 2008. Endozoochory by white-tailed deer (Odocoileus virginianus) across a suburban/woodland interface. Forest Ecology and Management. 255(3-4): 940-947.