THERE may be an innocent-looking culprit behind the widespread demise of songbirds in North America and Europe 鈥� deer.
Jean-Louis Martin from the Centre for Evolutionary and Functional Ecology in Montpellier, France, took advantage of the unusual ecology of the Haida Gwaii archipelago in British Columbia, where some of the islands have deer populations. Working with the Canadian Wildlife Service, Martin and colleagues surveyed songbird, deer, vegetation and insect populations on 37 islands.
They found the bird species that relied most on understorey vegetation for food and nesting were most affected by the deer. Their numbers were 93 per cent lower than those on deer-free islands (Biological Conservation, DOI: 10.1016/j.biocon.2005.04.001). Hardest hit were the song sparrow (Melospiza melodia), fox sparrow (Passerella iliaca) and the rufous hummingbird (Selasphorus rufus). A lack of predators has allowed deer numbers to rise, says Martin, who suggests introducing some of the deer鈥檚 natural predators.
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But we shouldn鈥檛 think of the deer as killers, he says. The fact that hoofed mammals are doing so well should be treated as a tremendous conservation success.
