The New York Times reports in its article Why Bambi Must Go – NYTimes.com how deer have had a destructive impact on some species of migrating warblers. Wildlife practices that have encouraged a growth of the deer population have resulted in a great decrease in habitat for warblers that forage near the ground. The growing deer population is eating much of the low growth of trees and shrubs. This destroys habitat that would normally safe for low nesting warblers such as worm-eating, Kentucky and hooded species.
The growing deer population is also causing more auto-deer accidents and increasing the population of disease-bearing ticks. Read more in the New York Times Why Bambi Must Go – NYTimes.com
Natural History Wanderings 
They just need to add a few wolf packs to the mix.
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By: John W. on May 26, 2012
at 8:51 AM
John raises an important point. When a predator is removed from an area, the species that was a food source for predator experiences large population growth with consequences for other species. See earlier posting How The Wolves Have Changed Yellowstone One of main predators of deer (and control on deer population) had been the mountain lion, whose population has greatly declined due to human intervention.
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By: Sandy Steinman on May 28, 2012
at 6:37 PM