Aug 19, 2010


By: Lorraine Julien

Illustration: Audubon’s Warbler by Louis Agassiz Fuertes.

This summer we’ve noticed lots of yellow flashes throughout the cedar bush near our deck. Sometimes the trees looked as though they’d been decorated for Christmas but on closer inspection, the bright bits of yellow were flocks of Yellow-Rumped Warblers flitting in and out of the branches in their search for bugs. Roger Tory Peterson, a well-known author of many bird guides, described these warblers as the “butterflies of the bird world” - a very apt description as that is just what they looked like.

The Yellow-Rumped Warbler has two distinct subspecies that used to be considered separate species: the “Myrtle” warblers of the eastern U.S. and Canada’s boreal forest, and “Audubon’s” warbler of the Western mountains. These subspecies may have slight colour variations especially where the ranges overlap, but generally, there are yellow patches on the top of the head, in front of the wings and above the base of the tail with contrasting black streaks. At 5 inches long and a 9 inch wingspan, with a thin, black, pointed bill, this is a medium-sized bird.

Yellow-Rumps are one of the first warblers to arrive in the spring and one of the last to leave in the fall. Arrival can be anywhere from late April to late May but is timed just right when the Ontario insect population is beginning to explode. The birds thrive on this “all you can eat” bonanza. They fly north as long as there are lots of insects. Populations of many warblers increase dramatically when there are outbreaks of spruce budworm and other insects. Baby warblers are stuffed with their own weight in insects every day and, as a result of this high protein diet, are able to leave the nest in just a couple of weeks.

A slang term for Yellow-Rumps is “butter butts”! This is probably because of the yellow patch above the rump but it also could refer to the voracious appetite of these birds. Yellow Rumps eat many things including caterpillars, beetles, spiders, ants, grasshoppers, mosquitoes, sap, seeds and berries of all kinds, including poison ivy berries! It’s this varied diet that allows them to stay in Ontario much longer than most other warblers. Some have been known to stay here as late as October, continuing to feed on any seeds and berries they can find. As much as I don’t like insects, once insect populations drop off, most songbirds, swallows, etc. begin their migration south and the forests and fields become eerily quiet again.

These small bundles of energy migrate at night when the air is cooler and calmer, usually at a height between 500 and 2000 feet. Most night flying is done on clear nights when they can follow the stars. Night-time studies conducted inside planetariums in the spring, indicate that white-throated sparrows, indigo buntings and other species flutter towards the North Star. Some studies show the birds must learn to migrate rather than just inherit the ability. During cloudy, rainy periods warblers (as most other small birds) are grounded but can spend the time resting and catching bugs to replenish the fat in their bodies.

To attract these beautiful birds to your property, try putting out sunflower seeds, raisins, suet and peanut butter. This spring, a neighbour gave me a large jar of peanut butter that was way past its prime but I put it to good use as an extra treat at the bird feeder. Though the peanut butter attracted various birds, chipmunks, etc., I was careful to put only enough out so that it was eaten during the daytime. To leave food out at night would only attract bears and raccoons and heaven knows what else.

Yellow-Rumps are one of the most abundant of our warblers and, at migration time, they seem to outnumber all others combined. Another interesting warbler, that I’ve heard but not seen, is the Ovenbird, so named because its nest is shaped like an old-fashioned oven and usually built on the forest floor. Its distinctive call is “teacher, teacher, teacher.” I used to call it the CB bird (before I knew its proper name) because the call sounded to me like “breaker, breaker, breaker”!

Observation: While driving home one afternoon recently, we noticed large flocks of American Goldfinches eating ripened weed seeds – one of their favourite foods and another indication that fall is just around the corner!

 

Please feel free to report any observations to Lorraine Julien at This email address is being protected from spambots. You need JavaScript enabled to view it.  or Steve Blight at This email address is being protected from spambots. You need JavaScript enabled to view it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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