Monday, August 8, 2016

17-year brood of cicadas becomes feast for Ohio birds

A periodical cicada, photographed in Ross County

August 7, 2016

NATURE
Jim McCormac

William Bradford, a five-time governor of Plymouth Colony in Massachusetts, was perhaps the first European to describe one of the world’s most incredible insect irruptions.

In 1633, the Pilgrims had been in the New World for 13 years and probably thought they had learned much about their adopted land. Surprises still waited.

That year saw the emergence of a brood of 17-year periodical cicadas in the Plymouth area. Bradford wrote the following in his "Of Plymouth Plantation," which documented early Pilgrim life: “ ... all the month of May, there was such a quantity of a great sort of flyes like for bignesss to wasps or bumblebees, which came out of holes in the ground … and ate green things, and made such a constant yelling noise as made all the woods ring of them, and ready to deaf the hearers.”

Periodical cicadas are far better understood today than in Bradford’s time. It took time to sort out the complex life cycle of these strange bugs, though. Nearly two centuries after the Pilgrims’ cicada encounter, Dr. Samuel Hildreth of Marietta, Ohio, began to ferret out the mysteries of these mostly subterranean insects.

Today, scientists have largely unraveled the mysteries of periodical cicadas. They spend almost their entire existence underground feeding on sap from tree roots. After 17 years, the nymph cicadas drill to the surface and transform into adults. The males then proceed to sing, creating the din that attracts so much attention.

The six-legged horde lasts a little longer than a month, beginning in late May and culminating in females depositing eggs within tree branches. These branches eventually drop to the ground, and the fledgling nymphs bore into the ground.

The periodic outbreaks vary from region to region, and each is numbered. Ohio hosts four broods, and 2016 saw the emergence of Brood V, which extends over almost the entire eastern half of the state.

For birds, the cicada emergence is like entomological M&M’s dropping from the sky. Almost every species that can catch the big bugs will eat them. I saw robins and red-winged blackbirds deftly plucking cicadas from the air.

The Ohio Ornithological Society queried its members and documented cicada feeding by 44 bird species. These included all our woodpeckers, the ring-billed gull, the screech owl, the Eastern bluebird and two species of raptors.

To me, the most interesting avian response involved cuckoos. We have two species — the yellow-billed and black-billed cuckoos — and both seemed to skyrocket in numbers. I saw or heard them everywhere I went in cicada country, sometimes five or six simultaneously.

Cuckoos apparently invade areas of cicada irruptions en masse to take advantage of the food bounty. They will even become brood parasites: Female cuckoos produce excess eggs that will be dumped in other birds’ nests.

Residents living within Brood V boundaries will enjoy 16 years of tranquility. But brace yourselves for 2033.

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.

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