Deer Preferences Promote the Spread of Non-Native Invasive Plants
Selective browsing by white-tailed deer likely is promoting the spread of some invasive plant species in northeastern U.S. forests, as deer avoid eating vegetation they find unpalatable.
This study provides evidence that deer impacts on plant invaders depend on plant species palatability. Consequently, deer selectivity likely plays an important role in the invasion process. To the extent that herbivory impacts plant communities, these results suggest that deer promote the spread of some plant invaders by avoiding them.
In the study, published this month in the journal Biological Invasions, researchers documented feeding preferences of eight mature does without fawns through three seasons — late summer, early autumn and spring. The 15 plant species were offered in containers where deer could choose among them. A camera activated by a motion detector and infrared-enabled for night viewing allowed the researchers to observe and record deer behaviors. The amount of each plant consumed also was measured.
While deer consumed more native than introduced plant biomass overall, their food preference varied strongly by plant species. Results show consistent deer avoidance of several invasive, introduced plants — garlic mustard, Japanese barberry and Japanese stiltgrass.
Deer also avoided one native plant, hay-scented fern. That species, which some researchers consider a “native invader,” is spreading in areas of forest underbrush where deer are abundant.
But other invasive, introduced plants — Oriental bittersweet, European privet, and Morrow’s honeysuckle, and a native plant, red maple — were highly preferred by deer.
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