Aggressive human activities like forestry or hunting are being blamed for centuries, for edging out forest birds. Then, what’s the reason for the decline in forest birds in the areas where humans don’t tread? It is not disease or loss of habitat or even an increase in the number of animals that prey on bird nests, factors generally held responsible. A new study has found deer responsible for the decrease in bird population in such areas where humans don’t venture. It is in North America, large populations of deer are edging out forest birds, report scientists in this month’s issue of the journal Biological Conservation. How? The study evaluated the impact deer grazing can have on nest quality and food resources in areas unaffected by human activities.
Few studies have considered the overabundance of deer, whose populations are reaching historic peaks. The white-tailed deer population, for example, is ecologically excessive in 73 percent of its range in North America, and other deer species tip the scales in up to 41 percent of their range. These animals can devastate a forest understory, which is used by some birds for nesting and also serves as a home to insects, worms and other invertebrates that birds rely on for food.