Why Bird Feeders Might Not Be as Kind to Some Birds as We Thought
Many people enjoy putting food out for their local garden birds, but a new study suggests that bird feeders might encourage non-native birds rather than supporting local species, and that could be a problem.
It’s estimated that around 40 percent of people in the U.S. put out food to encourage garden birds, but a study by Auckland University researchers suggests that, for some of the local bird population at least, the wider ecological impact can actually come with some concerning negatives about which we weren’t previously aware.
To assess bird feeders and their impact, researchers monitored over 20 Auckland gardens over a period of 18 months. Every morning the owners of those gardens would put out two of the most common foods that are offered by New Zealand bird feeders, pieces of bread and a store bought budgie seed mix. The researchers then recorded the species that visited the gardens, their feeding habits and general behavior. (For those interested in details on how the count was made, the Guardian has an extensive and easy to understand breakdown.)
The researchers found that of the 18,228 birds recorded during this study, there were 16 native species and 17 introduced species, and the data showed that the non-native species were far more likely to benefit from the feeders than their native counterparts. For instance, there tended to be more sparrows and spotted doves, which is great for those species who are thriving on a doubt a convenient food source. However, native foraging birds like grey warblers seemed to fair less well. In fact, the researchers found that grey warbler densities in those areas went down by more than half.
Co-author and PhD candidate Josie Galbraith is quoted as saying that the grey warbler’s decline at feeding sites is particularly concerning. “They typically forage on insects in the tree canopy but their ability to forage efficiently may be being affected by the disruption of higher densities of other birds at feeding sites. There is some evidence their numbers are declining anyway, so this study does add to that concern.”
Don’t misunderstand though, the researchers aren’t saying we should stop putting out food for our birds. Indeed, as The Nature Conservancy points out, other studies like one conducted relatively recently in Wisconsin in the United States show that for birds like the black-capped chickadee, bird feeders are vital for keeping birds fed during the tough winter months.
Also, we have to put this study in perspective. While in terms of reliability the study is a solid one, it obviously can only tell us about the species that were examined and the relationship between native and non-native birds in New Zealand. However, what it does suggest is that if we want to make sure we’re helping all birds, we might want to put a bit of thought into how we set up our bird feeding stations.
In the end, it seems to come down to what food we use. Grains and seeds seem to benefit non-native birds who don’t have a specialized diet whereas, in the warbler’s case for instance, those foods aren’t going to be that appetizing when the birds usually rely on meals of insects and grubs. So the solution is relatively simple: we need to try to cater to native species too.
A simple way to do that is to offer a variety of feeds. Also, creating bird feeding stations which more closely resemble how the birds would feed anyway is another great step; for instance to attract foraging birds we might try putting our feeders in or near to tress where there is plenty of cover. For those who like to forage on the ground, scattering seed and other food stuffs might be beneficial, as well as providing specially formulated bird nectar for those birds who have a sweet tooth, so to speak.
There was also one other take-away from the study: the researchers found that bird feeder hygiene was relatively poor. It might not be something we often think about, but giving our bird feeders a scrub twice or three times a year can cut the risk of birds picking up various infectious diseases like avian pox and salmonella, ensuring the birds we love to look at, and look after, stay fit and healthy and can continue to brighten our gardens year after year.
Do you have any tips on how to get the best results for feeding birds? Please let us know in the comments below!
Photo credit: Thinkstock.