Tag Archive | Brown-headed Cowbird

Wintering blackbirds in Texas

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

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

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

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:

Hairy Woodpecker:

Clay-colored Sparrow:

Black-capped Chickadee:

Rose-breasted Grosbeak:

Brown-headed Cowbird:

Some small mammals got in on the action as well.  Red Squirrel:

Least Chipmunk:

A Pine Siskin and a Red-breasted Nuthatch squabble over a good feeding spot:

Pine Siskin:

Red-breasted Nuthatch:

White-breasted Nuthatch:

Finally, this little Red Squirrel rested his head on his hands while he patiently waited his turn at the feeder:

Posted by Bob Lefebvre