Backyard feeders invite aggressive bird breeds, study finds

Flock of birds
Flock of birds. Credit: Wikipedia.

Backyard bird feeders may ruffle some feathers, attracting aggressive breeds like house sparrows and doves while discouraging native species that eat insects and nectar, researchers said Monday.

The experiment described in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal, set out to study how putting out seeds and bread may influence what kinds of birds inhabit certain areas, and if the hobby alters the birds' natural balance.

"Bird feeding is happening on such a massive scale globally—it is essentially a worldwide experiment," said lead author Josie Galbraith, a researcher at the Centre for Biodiversity and Biosecurity at the University of Auckland, New Zealand.

For a year and a half, scientists studied 23 residential gardens in Auckland, New Zealand.Eleven of the gardens contained bird feeders that were refilled daily with bread and seeds.The other 12 had no feeding stations for birds.

Scientists documented bird sightings with a total of 597 surveys that spanned more than 18,000 birds of 33 species.

They found that backyard feeders tended to favor non-native omnivores such house sparrows and spotted doves, as well as blackbirds and common myna.

"During experimental feeding, the feeding gardens had 2.4 times more and 3.6 times more spotted doves—both introduced species—than non-feeding gardens," said the study.

Homes with newly installed feeders saw a "dramatic" increase in the number of birds flocking to the feeder, and reported that the seed and bread was often gone in under two hours.

Meanwhile, diversity took a hit at feeding gardens, and the native grey warbler, whose diet consists mainly of insects, was seen less often where feeders were present.

The effects were temporary and reversible once the feeders were removed.

Bird feeding is common in the United States, Europe, and Australia.

New Zealand alone has about 265,000 homes that feed birds across six major cities, according to background information in the article, so the study focusing on just 11 bird feeding gardens was admittedly small.

But researchers urged avian enthusiasts to take a larger approach to welcoming birds, particularly those that naturally flock to fruit, nectar-producing flowers, and insects.

"We aren't suggested feeding should stop—it may actually be very important for urban-dwelling people as it gives them a connection with nature, which in itself has many benefits," Galbraith told AFP.

"We should be asking how we can encourage a diverse array of birds into our urban areas instead. Something everyone can do is create bird-friendly gardens by planting suitable trees and providing a water source."

She also said that people who keep seed in backyard feeders should be sure to clean them regularly, because they can spread disease among .


Explore further

Grey squirrels stop garden birds using feeders

More information: Supplementary feeding restructures urban bird communities, Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1501489112

© 2015 AFP

Citation: Backyard feeders invite aggressive bird breeds, study finds (2015, May 4) retrieved 25 June 2019 from https://phys.org/news/2015-05-backyard-feeders-aggressive-bird.html
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User comments

May 04, 2015
Then mice come in and eat what the birds drop. Then come the snakes after the mice. Bird feeders are nasty!

May 04, 2015
The squirrels like 'em...
And the stuff dropped? The neighbors chickens love it... We're their new best friends...

May 04, 2015
I saw a pterodactyl munching on some suet I put out a week ago.

May 04, 2015
I put a bird feeder out to entertain my cats. Thus Im helping to alleviate the pigeon overpopulation problem. You're welcome!

May 05, 2015
This study's generalisations are so* flawed. If you want to attract 'beneficial' species, you don't offer seed such as millet which attracts House Sparrows, doves and pigeons. You *especially* don't offer then bread, for pete's sakes, which is almost nutritionally useless for birds. *What* were these 'experimenters' *thinking*? For nectar-drinking birds, you put up nectar feeders and get hummingbirds and fruit-eating/drinking species, which are also insectivorous, thus falsifying this 'experiment's' conclusion about nectar-feeding species. You adopt different strategies. Suet for woodpeckers and gleaners of various species. Hulled sunflower seeds if you want to avoid House Sparrows. Niger sunflower feeder for the small northern species which irrupt into more southern latitudes, such as siskins, redpolls and Pine Grosbeaks. And, in North America, many of the species which consume seeds in the winter time are insectivorous come summer. Not in NZ. Sloppy, sloppy, sloppy.

May 05, 2015
My backyard tomato plants seem to be inviting species that like to sample each ripe tomato. My guess is they are mocking birds, and they are mocking me.

May 05, 2015
It depends where you're at, what you use and how you do it. I use a shielded feeder with baffles that keep out doves and rodents, and I feed with sunflower seeds. As a result I attract only native birds, various finches, chickadees, pine siskins in the fall migration, juncos for ground spill (finches are messy eaters), even the occasional flicker. I never see "pest" species like starlings, though in my book what succeeds deserves to live, that's evolution. I love the little birds in my yard, and if I'm disturbing the nature order, so what. Man IS the natural order now.

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