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Posts Tagged ‘Brown-headed Cowbird’

bird1

Northern Cardinal

This beautiful cardinal can be heard every morning now, singing out his song from a treetop perch. He’s been here all winter, but he has just started giving full voice to his chorus of “Birdie, Birdie, Birdie! Whit, whit, whit!” in the last week or so. What female could resist him?

It’s hard to believe that it was only last weekend that I spotted the first Red-winged Blackbird. Now they are everywhere, chucking and oak-a-leeing in the branches and foraging beneath the bird feeders. Over the course of the week, other migrants have joined them. There are quite a number of Common Grackles joining their numbers. Look at the beautiful iridescent colours on this fellow, helping himself to a seed at the feeder.

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Common Grackle

As I was walking past a pine tree, I noticed a Brown-headed Cowbird keeping a cautious eye on me. There have been a few American Robins around for a few weeks, but now they are back in plentiful numbers. And this morning, I spotted a pair of Hooded Mergansers on the river. They skillfully avoided my attempts to capture them with my camera, taking off for a site farther upstream.

The birds are early, ready to put The Winter That Wasn’t behind them and move on to spring. This winter was the 3rd warmest on record here. Three of the warmest winters ever have been recorded in the last six years. What was additionally notable about this winter was the lack of precipitation. It was also the second driest winter on record.

How are these shifts in winter weather patterns affecting migrating birds?

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Brown-headed Cowbird

A special report titled The Winter that Wasn’t: Bird Migration aired on CBC’s morning show The Current on March 7th. Biologist Allen Hurlbert from the University of North Carolina, B.C. biologist Dick Cannings and eBird editor Mike Burrell from Bancroft all addressed this question.

They note that the timing of migration is vitally important to the success of the upcoming breeding season. If a bird arrives back too early, he may encounter the bad weather and lack of food he flew south to avoid. If he arrives back too late, he may fail to find a good breeding territory and prospective mate.

One of the most important elements about timing is hitting the height of the insect season just right. Birds need a big supply of bugs to feed their demanding young. Without them, chicks may starve. If a warm spell disrupts normal insect patterns, causing bug populations to peak earlier, parent birds may not be able to adequately supply their young with food if they have started nesting according to their normal schedule.

We often have a poor appreciation of just how interconnected the natural world is. Failure or changes to one sector can have a ripple effect right through an ecosystem. Some bird species, such as Red-eyed Vireos seem to be adapting to changing weather patterns. Other species, such as Barn Swallows have been devastated. While Barn Swallows were once common birds, their numbers have plummeted by 75% over the last few decades.

You can learn more by listening to the full broadcast linked here.

bird2

American Robin

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As spring gently unfolds her warmth, the species of birds that frequent the backyard feeder are changing with the weather. Certainly, the feeder is still a major attraction. However, the Blue Jays that dominated the daily arrivals just a few weeks ago have now given way to Red-winged Blackbirds and Common Grackles. That’s not to say that the Blue Jays have disappeared, but fewer seem to be visiting. The American Goldfinches, on the other hand, are present in even greater numbers. The males are just starting to show signs of their spring spruce-up as their bright yellow breeding colours begin to replace their muted winter gold. A few days ago, the Goldfinches were joined by a few raspberry-bright Purple Finches. The Purple Finches weren’t regular winter visitors, so perhaps these few are just stopping by on their migration north. The wintering American Tree Sparrows are still here too. They will be leaving for their northern breeding grounds one day soon. I find that they tend to just disappear one day, replaced by similarly-coloured Chipping Sparrows as if by magic. The Chipping Sparrows breed here in the summer and winter farther south.

A few male Brown-headed Cowbirds have been joining the Grackles and Red-wings. I did see a few stray Cowbirds that visited a few times in the winter, but I think these individuals are probably here for the summer.

I like to watch the Grackles pointing. This “head-up” display is sometimes performed by females, but it is predominately a male posture, used both to attract females and as an aggressive signal to warn off other males.

In the photograph below, I caught a Grackle displaying with puffed-up feathers. It’s not clear whether his audience is impressed. The second Grackle looks a bit bemused by this performance, as if thinking “What the heck??” The display is another sign of spring and the new breeding season that is quickly approaching.

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By the beginning of January, the routine at the bird feeder is pretty well-established. I put seed out for the birds after I feed the horses in the morning. There is usually a crowd hanging about in the trees near the feeders, tapping their frosty little toes, waiting on me. Chickadees, juncos, tree sparrows, mourning doves and blue jays, lots of blue jays, are among the usual suspects. Recently, though, a couple of strangers have joined the crowd. A lone White-throated Sparrow (Zonotrichia albicollis) was keeping company with the tree sparrows for a couple of days.

White-throats are natty little sparrows, with striped heads and a white chin and a distinctive yellow dot at the lore, in front of the eye. In the summer, they breed across much of southern Ontario in small numbers, but their main breeding ground is far to the north in the boreal forest. It is common to hear them calling in the spring as they pass through the area on their way north. Their song is easy to recognize. It sounds like a whistled “Ohhhh! Sweeeeeeeet! Can-a-da-Can-a-da-Can-a-da!” I was surprised to find that the White-throats in Maine sing the same patriotic song, apparently missing The True North. The White-throat population is doing better than many other bird species, owing in part to their preference for the second growth forest that follows forest fires, or as happens often these days, clear-cut logging. White-throats are short to middle-distance migrants, moving south of the Great Lakes and down to the southern states. The stray White-throat I observed may not be too far north of his compatriots’ winter range, but this is the first White-throat I have ever observed in winter in Ontario.

The other unusual visitors were Brown-headed Cowbirds (Molothrus ater). A small group of five or six birds first showed up at the feeder together on Christmas day. Since then, a lone male has been a semi-regular visitor. Like White-throats, Cowbirds winter south of the Great Lakes, into the southern states. This is my first winter Cowbird sighting.

Cowbirds are brood parasites. That is, they lay their eggs in the nests of other birds rather than nesting themselves. They get their name from their habit of following grazing livestock, foraging on invertebrates stirred up by the animals. A female is usually courted by three or four males who follow her about. Cowbirds are most common where agricultural land suitable for foraging is interspersed with forest habitat appropriate for breeding. For this reason, the Cowbird population is the most concentrated in southwestern Ontario, although they are common breeding birds in this area as well.

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