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The great spring gamble

This story is featured in Montana Outdoors March–April 2013 issue

This time of year, it’s usually still winter in much of Montana. Not always, though. Early last April, for instance, spring came at us like a high-speed freight train.

Lilac bushes were beginning to leaf. Meadowlarks were singing. Gophers were running around. Bluebirds were flashing their electric color in front of windshields. All reliable signs that winter was over.

Each one of us has a peg to hang our seasonal hat on that signifies spring is approaching. And while we humans pay attention to the calendar and weather forecasts, plants and animals recognize spring by daylight length.

That’s not surprising. Despite all the variables in the environment from year to year, only the steady increase (spring) or decrease (fall) in seasonal day length remains constant. That’s because Earth never stops its steady rotation on its axis around the sun.

Bird behavior, like migration and nesting, is influenced a bit by weather. Yet even wet and cold spring conditions can’t stop bird migration for long. Longer days mean a bird’s just gotta fly north.

But what do birds do when they arrive in Montana in early spring and find ice, snowdrifts, and wind chills below freezing?

Some die, but many species have evolved to survive late-winter storms. For instance, robins that have begun to disperse to nesting areas go back into their winter flocks. They head to areas around open water, like the Missouri River, which can be warmer or at least out of the wind. Riparian areas also offer insects, which means food to help ward off the chill.

Most songbirds don’t start arriving this far north until May. Bluebirds are an exception, wintering from Utah and Arizona south through Mexico and arriving in north-central Montana in mid-March.

Several websites offer information on spring migrations. The Cornell Lab of Ornithology and National Audubon Society co-sponsor ebird.org, a site that maps weekly movements by species. Another is the American Birding Association’s website, aba.org. On the home page, click on “Birding News,” then scroll down to “Montana” for the latest sightings by fellow birders.

Warm weather in early spring draws out insects, a bounty for species like bluebirds. But a really bad spring snowstorm can mean no insects and conditions harsh enough to kill bluebirds.

Red-winged blackbirds, robins, and meadowlarks can survive cold, wet spring weather better than bluebirds can, because they don’t rely solely on flying insects. They find food such as seeds and crawling bugs on the ground. Even so, day after day of a lingering cold snap will take its toll on all returning migrants.

So why risk death just to be the first to arrive?

The early bird gets the worm, of course. But more important, the early bird gets the prime nesting real estate, which means a better chance to successfully hatch its eggs and raise its young.

So a bird can arrive early and hope the weather doesn’t take a turn for the worse. Or it can arrive late and hope that some decent nesting sites still remain.

Either way, it’s a gamble.Bear bullet

Bruce Auchly manages the regional Information and Education Program in Great Falls.

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