Quirks & Quarks

Backyard Bird Feeders Harm the Natives

Bird feeders in New Zealand provide food appropriate for invasive species which then outcompete natives.

Bird feeders benefit invasive species, not native ones

Spotted Doves and Sparrows on Feeder (Josie Galbraith)
Watching birds on backyard feeders is a favourite pastime in many places around the world. But it has been debated for years whether putting pieces of bread or a handful of seeds out for the birds is helpful or harmful. In New Zealand, where as many as 70% of people who have backyards in urban areas feed birds, the issue was put to the test.

Josie Galbraith, a PhD student from the School of Biological Sciences at the University of Auckland, experimented by setting up more than 20 urban feeding sites and watching them for 18 months. The results demonstrated that feeding actually favours non-native birds, like spotted doves and sparrows, whose populations dramatically increased.

Native birds, especially the gray warbler, suffered even though they do not compete for the food on the feeders. Their numbers decreased due to competition for habitat from the increasing non-native species. Similar results are predicted where feeders are popular anywhere in the world.           

Related Links

- Paper in PNAS
- University of Auckland release
The Guardian story
Wired story