More Deer = Fewer Birds

A new study shows for the first time that too many deer in an area equals too few songbirds. The laboratory was a chain of islands off British Columbia that either have no deer or have had deer populations for more than 50 years or for about 20 years. Scientific American Online reported:

The team found that the more a bird species relied on the forest understory for nesting and food, the more it was adversely affected by a sizable deer population. For example, on the islands browsed by deer for more than 50 years, bird abundance was 55 percent to 70 percent lower than on the deer-free islands. For those species that had the highest dependence on forest-floor plants, the numbers were dramatic. The fox sparrow and the rufous hummingbird, for instance, were common on deer-free islands but missing on the islands with a long browsing history.

The report also notes that an over-abundance of white-tailed deer – the species that we have here – is a common problem: in 73 percent of its range, it is “ecologically excessive.”

The study (which I first read about on DC Birding Blog) tends to confirm something that people around here have suspected for a while – that we have fewer songbirds because we have too many deer. Greenwich Audubon, among others, has tried to do something about it by conducting controlled hunts in recent winters. You can read about what they’ve done here and here.