The Yellow Invasion
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It is autumn, the leaves are turning colors with many of them yellow – but the yellow invasion happening last week was a yellow-rumped one.
As I walked out of my home early Thursday morning it sounded as if hundreds of birds were auditioning for “The Voice.” The trees were full of birds featuring 11 different species serenading me and playing tag with the bugs, but one specie dominated the singing and the catching of flying insects flittering about the yard – the Yellow-rumped warblers.
With the recent rain storms, these migrating warblers had probably been blown in as they looked for shelter as the storm hit. At times 10 to 15 of them would be sallying out of the trees and bushes picking off the lowly bugs buzzing around in the early morning sun. The number of both grew as the morning progressed.
After shooting some pictures, I decided to head to Beaver Dick Park to see what was happening there – more yellow-rumps; then to Camas – even more. They were everywhere I went. It seemed like the whole Upper Snake River Valley had been invaded by these warblers and their cousins. Three days later only a few remained.
The Yellow-rumped are usually the first warblers to show up in the spring and the last to migrate in the fall. They are also the most abundant and
widespread warblers in the nation and are made up of two subspecies. The Audubon in the West has a yellow throat while the Myrtle is the sub specie of the East that has a white throat. The two can interbreed causing different coloration of the throat as was evident last spring at Market Lake.
Their coloration in the fall is much less vibrant than in the spring with their mating colors. But the constant is a yellow patch of feathers on the lower back they show as they fly away; mooning observers as they disappear into the foliage.
Most of these birds will spend the summer in Alaska and Canada, but some nest in the high mountains of Idaho and have been known to raise their young in elevations up to 12,000 feet above sea level. The Targhee National Forest in Island Park is an area to find a few of the nesting pairs.
Both parents will feed the hatchlings until they are about four weeks old when the male takes over the duties while the female starts another clutch of eggs. Some pairs will nest three times during the summer as Mr. Mom takes care of the ones just learning to fly.
Even though they feed mostly on insects, the Yellow-rumped can also digest berries and fruit and will come to feeders for sunflower seeds and suet.
Their aggressive feeding habits will challenge other species for dining rights. Last week at Beaver Dick Park the Black-capped chickadees often battled
the warblers over a tree or a bush for bugs hatching on the Henrys Fork of the Snake River.
Most of the Yellow-rumped warblers will migrate to the Southern United States, Mexico or the Pacific Coast while a few will winter along area rivers where food can be found.
With the Indian summer we have been having, the Yellow-rumps have been joined by some late Yellow warblers and many Rosie-crowned Kinglets during this migration. The key to enjoying them is to recognize they are here as they may be gone the next day, heading for the warmer climates.
