Backyards could be a boon for urban birds

Field of Dreams taught us that if you build it, they will come. But the truth isn’t so straightforward, at least when it comes to birds and birdfeeders. Other backyard features are far more likely to entice birds than a fancy-looking seed dispenser. That’s one of a number of findings in a new paper from University of Illinois biologists J. Amy Belaire, Christopher J. Whelan, and Emily S. Minor.

The researchers point out that while parks and preserves are important refuges for urban wildlife, the so-called matrix – which they describe as the “mosaic of land uses between habitat patches” – is equally important. In many ways, it’s easy to manage parks and preserves, since they’re overseen in most cases by municipalities. It is far harder to manage property owners’ yards, which can add up to more than a third of the urban landscape. But if there was a way to manage them, then together they could form corridors that urban wildlife could use to move between larger patches of more natural habitat.

It’s a great idea in theory, but the problem is nobody really knows just what sort of effect managing a neighborhoods’ worth of backyards might have on local ecology. We know more and more about the ecology of individual backyards, and are starting to pay greater attention to cities as a whole, but at the intermediate level of streets or neighborhoods, there is a relative dearth of data.

That hole is precisely what Belaire and her colleagues aimed to fill, and to do it, they turned to Cook County. The county boasts Chicago, the third most populous city in the US, along with some 70,000 acres of forest preserves, most of which are riparian areas along the Chicago and Des Plaines Rivers and their tributaries. Could backyards serve as corridors to allow birds the opportunity to traverse the landscape? To find out, Belaire looked for birds during the June 4 – July 6, 2012 breeding season along transects up to one kilometer away from the forest preserves’ borders.

In addition to the bird surveys, the researchers distributed questionairres to homeowners designed to gather data about the types of plants in their yards, whether they used birdfeeders or birdhouses, and what sorts of water features they might have. They also inquired about the use of pesticides and about whether the home had outdoor pets. That data was evaluated at the yard, street, and landscape levels. Their findings were published this winter in the journal Ecological Applications.

The researchers observed 36 bird species in all, not including wide-ranging birds seen flying far overhead (like hawks). Twelve were year-round natives, 20 were native migratory species, and four were non-native birds. The most common species were American Robins, American Goldfinches, Northern Cardinals, and House Sparrows.

When it came to making for bird-friendly yards, birdfeeders and birdhouses were completely useless. Or, put more formally, there was no statistical relationship between using those devices and having lots of birds.

The most useful levels of analysis were individual yards and streets. Once the researchers zoomed out to the landscape level, the efforts of individual homeowners washed away. When multiple owners in a small area – within a 50 meter zone – did use bird-friendly backyard management strategies, the payoff was clear, and had a larger impact than any landscape level management activities.

So what did attract birds? Trees, for starters. Even better if it was a mix of evergeen and deciduous species, and best if they were mostly natives. In part, trees help to create habitat complexity, especially by adding more vertical habitat diversity. Residential areas are more savannah-like, and by planting trees, homeowners provide more mid- and upper-canopy level vegetation. Having lots of plants with fruits and berries was also a good indicator of bird richness. Together, streets with more bird-friendly yards had almost twice as many species as those without.

Unsurprisingly, the number of outdoor cats on a transect had a negative association with bird richness – with the exception of non-native birds, which were probably just better at avoiding cats. Invasive species, on average, tend to be scrappier than natives. Outdoor dogs were far less problematic, though migratory birds did seem to stay away from transects with more of them. While keeping cats inside keeps all birds safe, keeping dogs inside would still prove beneficial to the most sensitive of bird species.

All that data is great, but what use is it unless homeowners could be convinced to manage their yards in wildlife-friendly ways?

The researchers suggest that people might be more willing to take action when small behavioral changes can lead, in aggregate, to larger positive outcomes. They also suggest that grassroots efforts are more likely to be effective than top-down educational or incentive-based programs. Still, homeowners associations are in a position to motivate homeowners to manage their yards in ideal ways, and municipal programs can also be remarkably effective. The City of Chicago’s Sustainable Backyard Program, for example, offers rebates to residents for actions like replacing exotic with native plants.

Together, Belaire and her colleagues conclude by asking “why not ask more from our residential landscapes?” Indeed, backyards have the potential to be so much more than just a place to enjoy a barbeque or game of catch. – Jason G. Goldman | 15 April 2015

Source: J. Amy Belaire, Christopher J. Whelan, & Emily S. Minor (2015). Having our yards and sharing them too: the collective effects of yards on native bird species in an urban landscape. Ecological Applications 24(8), 2132–2143. DOI: 10.1890/13-2259.1.

Header image: Northern cardinal via shutterstock.com

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6 Comments

  • Janet Pesaturo April 15, 2015 at 7:21 am

    Makes sense! I started landscaping for birds almost 20 years ago, and removed the feeders almost 10 years ago. The species which typically visit feeders all still visit my yard, but of course don’t congregate here in the numbers they used to. And, as the trees and shrubs have matured, species that don’t visit feeders have moved in.

    Reply

  • Lucy Weinberg April 15, 2015 at 4:29 pm

    Native trees. The big NATIVE trees have the greatest observable biodiversity.
    Prof. Douglas Tallamy wrote about this in 2008 in his book “Bringing Nature Home” and the supporting data was available on the University of Delaware website. The critical elements are insects and plants, specifically herbivore insects and native plants. Healthy baby birds that are going to survive to reproduce need enough protein & calcium to support their rapid growth and this can be supplied by a healthy insect biomass. Native plants, including big native trees, provide the healthy insect biomass necessary for healthy bird populations. Any number of people have written up anecdotal descriptions of how they changed their yard from alien plants to native and have experienced a dramatic increase in bird traffic (ecosystemgardening.com)
    His next book on the subject is “The Living Landscape” written with Darke.
    If landscape architecture, botanical industry and horticultural industry people would open their minds and learn about the role of native plants & insects in ecosystems, there might be a future with more surviving bird species than the direction things are headed.

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  • Tim April 20, 2015 at 5:30 am

    The corridor notion implies birds move about randomly. However the same tree swallow came back to my box last week, suggesting that corridor is not relevant because the swallow simply flew straight to my yard. Same scenario for a Brown Thrasher that nests across the street but brings it’s young to my feeders. Both birds had young last year and contributed to the population. Both birds depended on a bird box / feeder.

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  • Andrew Gibbs April 21, 2015 at 3:02 pm

    I am a graduate student working on my PhD at Portland State University and I am working on a similar study, although on a much larger scale, in Portland. I am studying the effectiveness of the Portland Audubon Backyard Habitat Program. This article makes a dangerous statement about the uselessness of birdhouses and feeders. A bird house can only be used by a single pair at a time, which means the max it can increase a count is by a bird or two. Bird houses can be critical nesting spaces in urban (and managed forests) which are lacking any natural dead wood for nesting. Bird feeders are mainly important during the winter, when they provide high fat food for resident species. Nesting birds require insect larva for feeding young, and they mainly ignore feeders during the breeding season.

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    • Lucy Weinberg April 22, 2015 at 8:48 am

      What you have written sounds like what most of the usual Audubon people say and it always seems that Audubon is protecting their revenue stream of nesting boxes and bird feeding supplies. However, every bird watching trip that I have seen Audubon people lead is in “natural areas” where healthy native trees, shrubs & forbs support healthy insect biomass. I hope your study in Portland does not have predetermined results due to Audubon loyalty. All the best.

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      • Andrew Gibbs April 28, 2015 at 6:16 pm

        Your comment is offensive and disgusting. I do not work for Audubon, or have any loyalty to them. I am studying their program so I can determine if it works or not. Any feedback I have is greatly appreciated by them. What sense would it make from my perspective or theirs to create results that make it look like the program works, if it does not? You are attacking a person who has dedicated his life to understanding how the urban environment can be managed to create a world where humans and wildlife can live in harmony. Audubon fled trips are their business, and have nothing to do with me. However, their goal is to go to place where they can reliably find birds. If that is in someones backyard, how could they take you there? And on that note, the Portland Audubon has a garden tour every year to showcase their program, where homeowners in Portland allow open access to their yards. You know nothing about me, my work, or this program, yet you attack me.

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