I always know spring is here when I start to hear the phoebes, chickadees, and cardinals singing in the morning. Pleasant childhood memories of watching birds eat at our feeders and splash in our birdbath make me want to put a feeder up so my daughter can enjoy the experience. But I’m hesitant because I know that the artificial grouping of birds that occurs at feeders increases the spread of diseases. Much more could be at stake for bird species frequenting feeders, as described in an article* in the November 2008 issue of Frontiers in Ecology and the Environment.
Scientists in the United Kingdom reviewed over 50 studies addressing the effects on bird species of supplementary feedings. The scientists found profound effects, which vary dramatically between species. As suspected, supplementing the natural food sources with artificial sources, such as bird feeders, had positive effects on some birds species. These bird species lay eggs earlier in the season, experience reduced aggression between chicks, or spend less time searching for food, all of which can increase survival. However, some serious negative effects of artificial food sources were observed. Some birds that lay eggs earlier find themselves unable to find the natural food items necessary to feed their chicks. Feeders can also act as “ecological traps,” causing birds to settle in areas with low supplies of natural food sources. Other species increase their populations to sizes not sustainable without artificial food sources. If people stop providing food, the bird populations can experience drastic declines. Also, bird species that adapt well to artificial food sources will outcompete other species.
As is often the case with scientific research, the results do not provide a straightforward conclusion. Bird feeders appear to be helpful and detrimental, depending on the species. So what should bird-lovers do? Whenever possible, provide natural food sources for birds, such as trees, shrubs, and perennials that produce fruits, berries, seeds and flowers. Arrange the plants throughout your property to minimize clumping of birds. The National Wildlife Federation provides a list of the top 10 native species for each region in the United States. Check out eNature.com and the Lady Bird Johnson Wildlife Center’s website for more comprehensive information on native plant species in your area. If you want to make a substantial impact on native bird species, create a wildlife habitat that provides food, water, cover, and shelter to raise young. For guidance on creating a wildlife habitat, read about National Wildlife Federation’s Certified Wildlife Habitat program.
*Frontiers in Ecology and the Environment 2008; 6(9): 476-484