For the Birds Radio Program: Helping birds in cold weather
Spring migration is often characterized by unpredictable and bad weather—it’s hard to call anything “unseasonable” when wild fluctuations are pretty much what the season’s all about. But this year’s cold weather has been pretty exceptional no matter how you look at it, which has proven terrible for early migrants, especially American Woodcocks and Tree Swallows. Woodcocks are specially adapted for pulling earthworms out of soft, wet soil. Of course, so do robins, but robins have a major backup system—they eat lots of fruit, too. At least 80% of a woodcock’s diet is earthworms, and they don’t have a lot of easy-to-find alternatives. When the ground is covered with snow or frozen, it’s simply impossible for a woodcock to eat enough. Small wonder I’ve had several calls and emails about woodcocks turning up in people’s backyards, often weak and disoriented.
But at least woodcocks have enough bulk and body fat that if they’re healthy they can usually survive a few days without food. This year’s weather conditions have been much worse for Tree Swallows. The warm weather that followed the blizzards of early March brought in a host of early migrants including blackbirds, Song Sparrows, Yellow-rumped Warblers, and Tree Swallows. Blackbirds and sparrows feed on seeds, and if the cold snap was hard on them, they could still find enough food to keep going. Yellow-rumps and Tree Swallows are the first of their respective families to return in spring because they can digest fruits as well as insects. But even though they’re tiny and have a hard time, it’s still way easier for yellow-rumps to pluck fruit than Tree Swallows, and the warblers can also feed on a wider assortment of insects, plucking crawling and chewing insects out of tree buds, bark, and other places as well as by flycatching. Swallows are fairly restricted to flying insects. I’ve had Yellow-rumps at my own feeders a few times, coming for suet and mealworms—even desperate swallows don’t figure out bird feeders, period. I’ve read of several accounts of people inspecting their bluebird houses and scaring out a dozen or so swallows that had been huddling inside to stay warm. Scaring them out like this can be fatal, since they’re so stressed, so make sure if you do have a bluebird trail that you never monitor your boxes during severe weather or freezing temperatures.
What else can we do for birds that are stressed by weather? Sometimes backyard robins figure out to take fruit from bowls or feeders—when they figure it out, they particularly like frozen blueberries, strawberries, and raspberries. Don’t thaw the fruit first because if the temperature is below freezing the fruit will quickly refreeze, with the melted and refrozen juice cementing it all together.
Suet is of course an excellent offering this time of year. Birds digest fat very easily, and the important energy boost can be critical for migrants replenishing their stores and for local birds to maintain and gain weight preparing for the breeding season. During spring migration I provide both sunflower seed and white millet. I do scatter seed on the ground, but try not to set out more than could be eaten in a day since old, wet seed can foster fungal and bacterial growth, and many of the microorganisms are dangerous for birds.
Hummingbirds were a couple weeks ahead of schedule last week, but fortunately the cold snap slowed down their progress. By April 3, sightings of Ruby-throated Hummingbirds had been made throughout Ohio and Indiana and reached Chicago and central Iowa. They won’t continue to advance until the weather warms again, but then they move into north country pretty fast. You can keep track of where they are at Hummingbirds.net, so you can ensure that your feeders are ready and out to welcome the very first arrivals.