American Cuckoos

Yellow-billed Cuckoo, James Giroux

By: Jim Pauff, Travis Audubon Master Birder

Yellow-billed cuckoos are often heard calling in the distance.  Actually seeing one in the open, on the other hand, is like glimpsing a celebrity changing planes at an airport.  Their childhood goes by in a flash, too.  They go from egg to fledged bird in eighteen days.  Hold adults in your hand to band them and they cluck like little hens, scolding you; the feathers of their trophy tails detach easily.  When they arrive in Texas to breed, females stand their tails up like exclamation marks, then drop them down and flip them up again as mating signals.  Males land on females’ backs with a twig or caterpillar in their beaks, which apparently makes their girlish hearts go pity-pat.  Most birders never see this behavior because cuckoos are manic for concealment.  Binoculars must be pointed at the right place at the right moment, gazing up through limbs without many leaves.  Good luck stumbling onto that.

Cuckoos can’t maneuver through bushes with their long tails.  Like other long-tailed birds—great-tailed grackles for example—they fly more-or-less in straight lines with gentle ups and downs although their wings flap rapidly; grackles fold their tails into vee-shaped rudders, cuckoos tow theirs behind like brown ribbons.  Yellow-bills habituate countryside dotted with fair sized trees and undergrowth near water—deciduous jungle.  As neo-tropical migrants they are jungle birds half the year: they molt in Central and South America before flying north.  When they arrive in Texas, if there is not a pond or river nearby a wet drainage ditch will do if enough foliage surrounds it.  Then, tucked out of sight they make jungle-bird sounds.  They call with an accelerating “ku-ku-ku” like the soundtrack of a 1930s Tarzan movie.

There is a belief North American cuckoos don’t parasitize other birds—but they do, just not all the time.  The term for this is facultative parasitism, which is when an organism doing well on its own takes advantage of an opportunity.  Wild ducks are facultative parasites on one another.  Studies suggest yellow-bills parasitize non-cuckoos during abundant food years when there is an outbreak of hairy tent caterpillars.  During those happy times they raise broods of their own as well as drop eggs into others species’ nests as a sort of selfish share-the-wealth scheme.  Scientists in Wisconsin in 2010 observed red-winged blackbirds raising a cuckoo from an egg dropped late into their brood, that nevertheless out-competed older nestmates for food.  The cuckoo chick stood on the bodies of its adopted older siblings, hissed rather than twittered, flapped its wings, vibrated its head, and gapped showing cream-colored dots inside its throat, and the redwings fed it well.  Unfortunately all the nestlings were eaten by a predator one night before they fledged.  This was really too bad because it is rare to observe in detail cuckoos being raised by proxies.  To re-coin Ursula Bloom, survival is a game played without an umpire.  Both cuckoo and redwings lost and the predator—the scientists guessed it was a raccoon—won.

Pictured: Yellow-billed Cuckoo. Photo by James Giroux.

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