The Story of Cowbirds and How They Threaten Other Species of Birds

Updated on May 8, 2018
Casey White profile image

Dorothy is a Master Gardener, former newspaper reporter, and the author of several books. Michael is a landscape/nature photographer in NM.

Is This the Devil of Birds?

This is a male, brown-headed cowbird. They are considered to be nest parasites.
This is a male, brown-headed cowbird. They are considered to be nest parasites. | Source
The female cowbird actually replaces an egg in the nest of another bird with one of her own, so maybe she is the actual devil of birds.
The female cowbird actually replaces an egg in the nest of another bird with one of her own, so maybe she is the actual devil of birds.

They Put Their Energy Into Producing Eggs

When photographs of cowbirds are posted on the web, people respond by saying things like: "I hate those birds!" or "I have tried to run them off from my backyard." They post such comments because of the female cowbird's unique way of raising her young, which is to not raise them at all.

Rather than spending any time building a nest for her eggs, the female cowbird puts all of her energy into producing eggs and does so at the rate of up to three dozen in a single summer. When she is ready to lay her eggs, she begins to look for nests that other birds have constructed (or have already constructed). When the host bird is not at the nest, the female cowbird slips in and pushes one of the eggs out of the nest and replaces it with her own, referred to as "nest parasitism". The baby cowbird is often raised by the unsuspecting host bird, who becomes a foster parent through no fault of her own.

Should the host bird destroy the cowbird's egg, the cowbird will often retaliate by destroying the entire nest in what many people have referred to as "mafia behavior."

"Chester" the One-Legged Cowbird

This is one of our backyard cowbirds that we have named Chester.  He has no trouble keeping other with the others that occupy our backyard sanctuary.
This is one of our backyard cowbirds that we have named Chester. He has no trouble keeping other with the others that occupy our backyard sanctuary. | Source

Don't Search for Nests

If you are the kind of person who likes to search for nests, don't do it when cowbirds are around. You may be aiding and abetting them in their search for nests in which to place their eggs.

How to Deter Cowbirds

To deter cowbirds, only use feeders made for smaller birds, such as tube feeders with short perches and smaller ports (with no catch basin at the bottom of the feeder). Stay away from platform trays and NEVER spread food on the ground.
Put out the food that cowbirds don't prefer, such as suet, whole peanuts or safflower seeds. Steer clear of the things they do prefer, like sunflower seeds, cracked corn, and millet. Always clean up any feed that spills over to the ground below your feeders.

Cowbirds are native to the United States and as such are protected under the Migratory Bird Treaty Act. It is unlawful to use lethal control without a permit (in most instances), which includes the removal of their eggs from a nest. There are occasions, however, when unpermitted control of cowbirds can be permissible (under special circumstances that are outlined in the act). In Michigan and Texas, you can obtain permits to trap the cowbirds if they are threatening the survival of endangered species like Kirtland’s warbler, golden-cheeked warbler, and black-capped vireo.

Host Species Baby Birds Suffer

When the unsuspecting foster parent bird raises the young cowbird, it is usually done at the expense of her own babies. The cowbird eggs require a shorter period of incubation than most other songbirds, so they usually hatch first and grow large very quickly, allowing them to get the most food from the parent birds. The nesting success of the host species is significantly lowered because of the actions of the cowbird hatchling.

Because the cowbird doesn't depend on a single host species exclusively, the impact of the actions is spread across many populations. Over 200 different species of North American birds are known to have been affected when their own eggs are tossed out of the nest, only to be replaced by the egg of a cowbird.

There are bird species that recognize that an egg is not their own, such as the yellow warbler. Those birds will either remove the egg from the nest or simply build another nest right on top of the cowbird's egg. Some people think that the birds that do accept the eggs and raise the hatchling as their own are simply doing it for self-preservation because of the cowbird's reputation for the destruction of any nest that rejects their egg.

Apart from the New World cowbirds, avian brood parasites include Old World cuckoos, some African finches, African and Asian honeyguides, and the South American black-headed duck. Opportunistic egg-dumping occurs among swallows, waterfowl, and others, but these guys (cowbirds) are pros.

— Joe Eaton, in an article written in 2007 in The Berkeley Daily Planet newspaper

They Began Acting Out of Necessity? Maybe

One theory (the one that is most accepted) is that cowbirds may not have malicious intent on their minds when they expect other species of birds to raise their young. They may have begun acting out of a natural necessity to ensure the survival of their own species. At one time, these birds followed the massive herds of bison across North America. They were able to feed on the insects that were kicked up by the huge bison's hooves, and also on the seeds that were displaced by the hooves.

The bison herds were constantly on the move, so the cowbirds had to follow. If they had stayed in one place long enough to raise their young, they would have perished so they altered their strategy of breeding. When the bison herds disappeared, the cowbirds adapted by following domestic cattle that had inherited the range from the previous herds that were no more.

Another theory is that they were only able to follow the bison herds because their breeding strategy, which already existed, allowed them the freedom to do so.

No one can say with any certainty if either of these theories holds water.


  1. (Retrieved from website on 5/8/2018)


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)