Tag Archive | Brown-headed Cowbird

Cowbird and Yellow Warbler

Tony LePrieur took these great photos of a huge Brown-headed Cowbird fledgling being fed by its foster parent, a male Yellow Warbler.

Brown-headed Cowbird being fed by a Yellow Warbler, Calgary, July 8, 2017. Photo by Tony LePrieur.

The warbler is off to find more food for its demanding foster child.

Brown-headed Cowbirds lay their eggs in other birds’ nests and often the other species does not recognize the difference and raises the young cowbird. For more photos of cowbirds with some other host species see these posts:

Cowbird vs Chipping Sparrow
Angry Birds
Cowbird Catastrophe, which includes an explanation of cowbird behavior.

Angry Birds! (…actually just Brown-headed Cowbird fledglings)

Jul16

Posted by Bob Lefebvre

Brown-headed Cowbirds are obligate nest parasites, so they do not nest or raise their own young – the female cowbird lays her eggs in a number of nests of other species. If the host birds don’t realize that they are incubating a foreign egg, they will feed the cowbird chick until it fledges and for a while afterwards, until it can forage on its own and rejoin its cowbird cousins.

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Brown-headed Cowbird chick, just out of the nest and begging for food. (All photos taken by Tony LePrieur, July 1, 2016.)

Many of the songbirds that are parasitized in this way are quite a bit smaller than cowbirds, so it makes for a comical sight when the “parents” are feeding their giant “offspring”. It’s no joke for the host parents, though, as this is a great drain on their food-gathering resources, and it has a negative impact on their ability to raise their own biological young.

Tony LePrieur has recently seen a number of young cowbirds being fed by different hosts in the Calgary area. Thanks to Tony for these fantastic photos!

Song Sparrow (left) feeding a Brown-headed Cowbird chick. Sikome Lake, Fish Creek Provincial Park.

Calling for food from the host Song Sparrow.

Another cowbird being fed by a Western Wood-Pewee, not far from the Song Sparrow and chick at Sikome, Fish Creek Park. This could very well be a biological sibling of the bird being fed by the Song Sparrow.

The Western Wood-Pewee adult, probably a little worn out from trying to provide for the cowbird chick.

Two cowbirds were being fed by a pair of Savannah Sparrows at Frank Lake, also on Canada Day.

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A close-up taken from the above photo.

Those of you with teen-aged boys will know how this Savannah Sparrow feels 🙁

Cowbirds also often parasitize Clay-colored Sparrows and even smaller birds like Yellow Warblers and House Wrens, so if you see any of those species carrying food, watch to see if they are feeding cowbirds.

Do you have photos of birds taken in the Calgary area? Send them to us and we may post them on the blog! birdscalgary@gmail.com

Wintering blackbirds in Texas

Dec1

Winter leaps upon us in a flash. One minute, it seems, it is a very distant shape looming faintly on the horizon. Suddenly, before we know it, winter has struck, leaving us wondering where the summer went. In Texas, the same seems to happen with wintering birds. One day, only the year-round residents who call Texas home can be seen. The next day, countless wintering birds of all shapes and sizes are everywhere, confusing even the most attentive eye.

Countless blackbirds flock together during the winter

On a recent trip to Brazos Bend State Park here in Texas, about an hour southwest of Houston, we observed some spectacular flocking in action. Literally thousands upon thousands of blackbirds; Red-winged Blackbirds, Brown-headed Cowbirds, Common Grackles and European Starlings congregating on some farmer’s fields. They swarmed and swirled, seemingly in perfect coordination, lifting off and landing as a unit. And yet, this is not a sight you can readily behold on these bird wintering grounds. You don’t see flocks of thousands of these species doing this in the summer, so why do they do it in the winter???

These blackbirds have quite a few reasons for doing this in the winter but these flocking habits also have numerous downsides. First of all, on the positive side, foraging is greatly improved by the large flock as opposed to a single bird or a small group. The more eyes you have working together, the easier it is to find food! More eyes can also mean more safety from would-be predators, and trust me, there are a lot of them!

This brings us to one of the downsides of wintering flocks. Predators. Lots of them. Where there is food, there are consumers, waiting to, well, consume the food. Raptors see these blackbirds as one huge buffet just waiting to be sampled. In a small farmer’s field, we counted up to 20 raptors: about 10 Caracaras, many Red-tailed Hawks, several White-tailed Hawks, a Turkey Vulture and a couple of Northern Harriers, all exploring the delightful opportunity of a full stomach all winter long. If these hawks were to stick with the group of blackbirds, they could potentially always find one or two to pick off from the pack. The more birds in a flock, the more noise and commotion they make, rendering them easily visible targets.

Large concentrations of any living thing invariably bring with them two other depreciating factors; disease and competition. Avian diseases can be spread very quickly in such large flocks and may sometimes ravage a great portion of the local species. More birds might find better food sources but if there isn’t enough to go around, there simply isn’t enough. Weaker, slower and sick birds often will be the first to go hungry as they cannot compete with the healthier individuals.

It was definitely a neat sight to behold, especially when a raptor would plunge into the center of the throng, sending up explosions of blackbirds. One of the White-tailed Hawks that we spotted, an immature, had a very full crop (a muscular pouch near the throat used to store food), showing us that it had been eating well recently.

In the end, the advantages of these congregations greatly outweigh the disadvantages and it is a bewildering sight that will continue to captivate many a fortunate observer.

Posted by Matthew Sim

Cowbird vs Chipping Sparrow

Aug9

We received an email from Larry & Angie in Innisfail a while ago, asking for help identifying a bird in their yard. They were confused because this bird was acting like a baby sparrow, being fed by an adult sparrow but appeared to be bigger than the adult. Their photogenic picture does a wonderful job of showing a juvenile Brown-headed Cowbird in action, and the difference in size between the two species.

As Matthew mentioned in his July Cowbird Catastrophe post on this blog, Cowbirds do not look after their own eggs, but lay them in the nests of other species. This poor Chipping Sparrow has already been outsized by this demanding youngster, and continues to burn up energy finding enough food for it. As Cowbird eggs hatch sooner than those of other birds and fledglings are known to eject the nest occupants, it’s likely this Chipping Sparrow did not raise any of his own young this year.

Posted by Pat Bumstead

Cowbird Catastrophe

Jul15

The Brown-headed Cowbird has become a menace to songbird populations all over North America. A small, stocky blackbird, the males have glossy black plumage and a rich brown head whereas the females are drab brown birds. What makes the Brown-headed Cowbird such a menace to songbirds is the lazy manner in which they raise their young. Females will use all their energy over the breeding season to produce eggs, sometimes up to 50 a summer. They lay these eggs in the nests of unwary birds; usually at the cost of the smaller bird’s young. The young cowbirds usually hatch earlier than their foster parents chicks and therefore, get most of the food, which can ultimately lead to the death of the foster parent’s young. The Brown-headed Cowbird parasitizes more than 200 species of birds; the Chipping Sparrow being one of the most hard hit species.

In the above photo, there are 4 male cowbirds all looking up from my bird feeder at the arrival of a juvenile Grackle.

There is a history behind the cowbird’s parasitism. At one time, it followed the buffalo herds across the prairies, a nomad, and therefore could not raise its young, resorting to the help of unwitting songbirds. Following herds of buffalo, the Brown-headed cowbird’s range was limited to plains and prairies. Deforestation and forest fragmentation by humans, however, opened up the way for the cowbird and they started to parasitize more and more species. Due to deforestation, the cowbird has expanded significantly, both in range and in number and it now poses a threat to some species.

Several species, such as the Yellow Warbler, have developed defences against cowbird parasitism and recognize the cowbird egg. The female Yellow Warbler will make a roof over all the eggs, including her own, upon recognizing the cowbird egg. She will then lay her eggs again. Other birds will throw it out of the nest or abandon the nest all together.

This one species goes to show how much human actions can change the world around us.

Posted by Matthew Sim

The Lookout

Jun29

In South Glenmore Park, just where the trail drops down into the Weaselhead, there is a path leading through the bush to a spot with two benches.

Not only does it provide a great view of the pond and Weaselhead, but someone has turned it into a feeding station for the birds. I have been there a few times, and there is always birdseed on the rails and ground, and oranges in the trees. If you sit still and are patient, you get great close-up views of the birds. These pictures were taken on June 17, and we saw 23 species from the lookout that day. Here are some of them. You can click on the pictures to enlarge them.

Downy Woodpecker: