Nature: Spread of humanity taking toll on songbirds

A male chestnut-sided warbler forages in new oak foliage/Jim McCormac

Columbus Dispatch

May 19, 2019

NATURE
Jim McCormac

Each spring, a migration of epic proportions takes place. Songbirds of many species return to nest in Ohio, or pass through on a long journey to points north. Their ranks include many favorites such as orioles, swallows, tanagers and warblers.

Most of our highly migratory songbirds are neotropical — species that breed at northerly latitudes but winter in tropical haunts. That Baltimore oriole whose flashy orange-and-black plumage and cheery flutelike whistling you enjoy wintered in Costa Rica or elsewhere in Central America. If you’re lucky enough to lock eyes on a neon-red scarlet tanager, marvel in the knowledge that it likely travels more air miles annually than you do. Tanagers mostly winter in the Andes of Colombia, Ecuador and Peru.

Long-distance travelers such as these make up a big chunk of our songbird diversity. There are about 135 species of songbirds that occur annually in Ohio (this excludes many species of non-songbirds, or nonpasserines). Of them, 70 species, or just over half, spent the winter south of the U.S. border.

About 100 species of songbirds nest in Ohio. More than half of them, about 55 species, are neotropical migrants. It would be unfair to think of such birds as “Ohio” birds. They belong to the Americas, as their passage takes them through potentially many countries and numerous states. Some birds occupy their wintering grounds far longer than the breeding grounds. For instance, orchard orioles and prairie warblers arrive to nest in mid- to late April. The males, who depart before females, start reappearing in the Caribbean and Central America by the end of July.

Our largest family of songbirds is the warblers, and they are the most popular group among birders. Thirty-seven species pass through Ohio or remain to nest every year. Collectively, all these warbler species wintered in nearly every country south of the U.S., with the lion’s share in Central America — the locus of their evolutionary origin.

Warblers, in general, are not faring well. The chestnut-sided warbler pictured with this column is an exception. John James Audubon, the energetic naturalist/ornithologist who roved widely throughout eastern North America, encountered this species only once. He shot five chestnut-sided warblers in May 1808 near Pottsgrove, Pennsylvania, but never saw another.

Today this bird is far more common, a beneficiary of clearing of primeval forests, which created lots of scruffy woodlands that the bird favors.

A more typical trajectory is that of the cerulean warbler, the totem of the Ohio Ornithological Society. Its numbers have plummeted by 80% over the past five decades. Mass cutting of the old-growth woodlands that it favors is a major cause of decline.

Burgeoning human populations have made life much more difficult for migratory songbirds. In 1800, only about 1 billion people occupied the planet. Today, there are more than 7.7 billion of us, and much of that growth has been in the Americas. We’ve destroyed habitat, erected a gauntlet of skyscrapers, wind turbines and transmission towers that many birds strike, and unleashed hordes of feral cats. All of these things and more have taken a big toll on songbirds.

I penned this column last Sunday, International Migratory Bird Day. Magee Marsh Wildlife Area on Lake Erie, near Toledo, is a hub of birding activity. Tens of thousands of birders descend on Magee’s fabled “Bird Trail” during April and May.

Birds are environmental barometers, and as they fare, so probably shall we, eventually. The more people watching birds the better, as birds are a great catalyst to promote environmental protection.

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.