Another mild winter and its effect on nesting birds

Great Blue Herons come back in mid-March. Will they return early if we have warm weather an open water?

Years ago when I started leading nature programs during winter, we considered February a month for snowshoe hikes and ice fishing. As snowfall has become less predictable, I started calling my February outings “hikes” rather than “snowshoe hikes.” Even if we don’t have snow, February is generally cold enough that we can hike over thick ice on marshes and lakes to find tracks or explore muskrat lodges.

The last three winters not only have deprived me of reliable snow in central Minnesota, but ice has been unsafe – not only in thickness but in coating my favorite hiking trails.

Leaving my home for work today, I heard black-capped chickadees and Northern cardinals singing territory songs. This is not out of the ordinary. As daylight length increases, bird breeding hormones accelerate, and they sing on sunny February days. In some winters it’s practice, but if it’s warm enough, some birds will attempt to nest. If they’re successful, they will keep at it. If they are not successful they’ll re-nest when it’s warmer.

Chickadees will start checking nest boxes in March.

Some bird species will attempt nesting when it’s unseasonably warm and gamble that it will stay warm enough for the chicks and provide ample food. Some classic examples of this nesting strategy are with exotic or introduced species like house finches, house sparrows and pigeons. They nest multiple times of year, so if they can squeeze in one extra early one all the better.

The bald eagles featured on the Minnesota DNR’s Eagle Cam are another good example. Typically bald eagles in Minnesota commence nesting in March, but this particular pair had eggs in the nest in late January to early February. The first year the camera was on the nest the birds laid in eggs in January and it was a particularly brutal winter. The birds periodically left the eggs unattended for long periods of time and the eggs never hatched. The last few winters, however, have been mild and with the open water and available road kill, the eagles have successfully hatched and reared chicks.

Looking at a Minnesota week of February where we’ll hit 60 degrees potentially several times, I wonder if we might see a few early arrivals and attempts at early nesting. Our most likely early candidates include waterfowl, herons, and blackbirds. Some of these species might try to nest, and if they are successful, this is how bird population shifts happen.

Other birds that typically start staking out nesting territory in March include woodpeckers, black-capped chickadees, wood ducks and red-tailed hawks. Watch for those species especially if you place nest boxes in your yard.

Categories: Sharon Stiteler

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