SCOTT SHALAWAY Cuckoos are birds of a different feather

While searching the forest canopy for the male scarlet tanager I had just heard -- its raspy voice sounds like a robin with a sore throat -- I caught another bird sailing by the edge of my peripheral vision. It disappeared into a dense thicket so quickly I saw it for only a moment.
I mentally reviewed the general impressions the bird had left on me. It was blue-jay size. Slender. White below and dark above. But most importantly, the tail, which fanned as the bird pulled up to enter the thicket, consisted of white-tipped feathers that shortened abruptly from the center to the outer edge. This combination of characteristics convinced me that I had seen a cuckoo.
But which one? Both black-billed and yellow-billed cuckoos inhabit wooded areas throughout the eastern United States. Farmers call them rain crows because of their habit of singing before thunderstorms. Their & quot;songs & quot; -- black-bills say & quot;cucucu, cucucu; & quot; yellow-bills, & quot;kow, kow, kow, kowlp, kowlp & quot; -- are simple and not at all musical.
The bird remained quiet, so I had to find it again to identify it. I sat down and watched the thicket the bird had entered. After a few minutes, some leaves moved. I scanned the area with my binoculars.
I made a & quot;pishing & quot; sound, a universal bird call many birds find irresistible. Suddenly, the bird appeared on an open branch. As it perched, I could discern the distinctive two-forward, two-backward toe arrangement shared by all cuckoos. The red eye ring, all-black bill, and small white tail spots made it a black-billed cuckoo.
Had it been a yellow-bill, the lower half of its bill would have been bright yellow, the eye ring paler, and the white tail spots much larger.
Bird food: Cuckoos eat everything from insects to bird eggs, frogs and berries. After returning from a winter in South America, they are no doubt hungry. One of their favorite foods is hairy caterpillars. In the spring that means tent caterpillars -- the ones that hatch in the tentlike webs so common this time of year.
They also eat gypsy moth caterpillars, and while there is no way cuckoos can begin to control an outbreak of gypsy moths, it's reassuring to know gypsy moths have at least a few natural predators. Tanagers, orioles and vireos are also among the relatively few birds that eat hairy caterpillars.
Caterpillar connection: Because these caterpillars are such important foods, cuckoo breeding cycles coincide with caterpillar infestations. They even lay more eggs when caterpillars are abundant. When hairy caterpillar populations are low, cuckoos may lay only two eggs. But when caterpillar populations soar, they raise as many as five young. Judging by the number of caterpillar tents I'm seeing this year, it should be a great year for cuckoos.
The pale blue-green eggs are laid at intervals from one to three days, and incubation begins with the laying of the first egg. This leads to asynchronous hatching -- each egg hatches about 14 days after it's laid. Consequently, a cuckoo nest can have as many as five sizes of chicks, each a day or two older than the next. This gives the older chicks an advantage. If food gets scarce, the larger chicks out-compete their nest mates for parental attention at meal time, and the younger siblings starve.
Home tweet home: A cuckoo nest is a rickety affair, not much more substantial than a morning dove nest. Viewed from below, light often passes through the maze of twigs cuckoos call home. Perhaps this is why cuckoos keep nest time to a bare minimum. A week after hatching, young cuckoos climb around the branches near the nest, and they can fly at three weeks of age.
Both parents share the incubation duties, and they also share the responsibilities of tending to nestlings. When it's time to leave the nest, the male tends to the first fledglings, and the female takes care of the younger half of the brood.
Compared to the more familiar forest birds we see every day, cuckoos differ in voice, behavior and even toe arrangement. Maybe that's why we call them cuckoo.
XSend questions and comments to Dr. Scott Shalaway, R.D. 5, Cameron, West Virginia 26033 or via e-mail to sshalaway

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