Nature: Brood X will bring out black-billed and yellow-billed cuckoos who feast on cicadas

 

Nature: Brood X will bring out black-billed and yellow-billed cuckoos who feast on cicadas

In my last column, I wrote about the impending eruption of Brood X 17-year cicadas. They’re in full cacophonous swing now. If you live in an emergence area, you know. Depending on one’s outlook, the cicadas are annoying pests or a rare opportunity to witness one of nature’s greatest entomological spectacles.

The black-billed cuckoo would take the latter viewpoint. Cuckoos are voracious cicada predators and take full advantage of emergences such as Brood X.

Cuckoos are fascinating and poorly understood birds. Two species occur in Ohio: the aforementioned black-billed cuckoo, and the more common and wide-ranging yellow-billed cuckoo. Although they look like songbirds, cuckoos do not belong to the giant order Passeriformes, which includes songbirds. They are much more closely related to owls.

While yellow-billed cuckoos nest commonly statewide, black-billeds are most frequent in the northern third of the state, but even there are outnumbered by the former.

Brood X should turn that distribution and abundance status on its ear this year. Black-billed cuckoos — yellow-billeds, too — converge on cicada emergences in big numbers. It’s as if the birds have their own Nextdoor app to clue them in. The mechanisms that allow them to locate cicada emergences is not understood.

One would think that a bird that’s bigger than a robin would be easy to study. Not so. Cuckoos are quite secretive and given to skulking in dense vegetation. Their loud, distinctive calls are often the only evidence of their presence.

Even at the late spring date of this column, cuckoos are still arriving. They have a long trip to get here. Black-billed cuckoos winter in western South America, from Colombia south into Peru. Next to nothing is known of cuckoos in their tropical haunts.

In 2016, when periodic cicada Brood V emerged over much of eastern Ohio, I was stunned at cuckoo numbers. It seemed that everywhere I stopped, cuckoos of both species would be calling. In areas where the black-billed cuckoo would normally be unusual, they were commonplace.

Billions of easily captured, six-legged flying steaks make for easy pickings, and small wonder cuckoos capitalize on the bounty. They are well-known for exploiting caterpillar outbreaks, too, and when food is plentiful breeding success spikes.

Food outbreaks can trigger an unusual behavior in cuckoo reproduction: brood parasitism. Ample nutrition allows female cuckoos to produce an excess of eggs. They’ll dump some in other birds’ nests, in the hopes that the unwitting hosts will raise the cuckoos. Host species include American robin, chipping sparrow and gray catbird. Sometimes even yellow-billed cuckoos fall victim.

Our cuckoos seemed to have evolved with insect booms, especially those of caterpillars and cicadas. Feathered nomads, they congregate where the outbreaks occur. Unfortunately, natural insect cycles are not what they used to be.

Naturalists described “flocks” of cuckoos descending on insect emergences in the late 1800s. No one sees such numbers these days — there are far fewer cuckoos. Ill-devised “pest” management and massive alterations to forested habitats have wrought havoc on natural insect cycles, including periodic cicadas. The animals that evolved to exploit these booms, thus providing natural controls, have also been greatly reduced in number.

But for cuckoos in the Brood X zone there will be food aplenty, and hopefully scores of little cuckoos will result.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.