Banning deer boosts migratory birds

Fencing out deer improved the bird world—at least from a conservationist’s viewpoint—in protected woodlands, report Virginia researchers.

In a 9-year test, excluding deer raised the population numbers among bird species, such as hooded warblers, that have a high conservation priority, say William J. McShea and John H. Rappole of the National Zoological Park’s Conservation Research Center in Front Royal.

Populations of other birds, such as chipping sparrows, decreased, the researchers report in the August Conservation Biology.

Sorting out how deer act as landscape engineers has inspired various tests. McShea and Rappole approached the problem by choosing eight plots of 4 hectares each. Using 3-meter-high fences, the researchers excluded large, far-ranging animals from half the plots.

The no-deer zones grew dense with plants, and populations of birds that prefer open woods dwindled. Meanwhile, creatures of more mature forests gradually increased. Using conservation priorities from the Partners in Flight coalition (See, the scientists calculated that denser woodland with fewer deer benefits bird conservation.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.