Hurricane season takes toll on birds

A ruby-throated hummingbird clings to a twig whipping in the wind in coastal Louisiana, waiting out the worst of Hurricane Harvey before its 500-mile flight across the Gulf of Mexico on the way to Costa Rica.

An Eastern meadowlark, on its way from Minnesota to Belize, senses a drop in barometric pressure and turns around, flying a few hundred miles north to wait out Harvey.

In Cuba, as wind and rain picked up ahead of Hurricane Irma, island naturalists fretted over the fate of the island's unique bird life — if significant numbers of birds like the Zapata sparrow didn't survive, how would this affect their species?

Hurricane season means pounding winds, flooding rains and punishing storm surges in a normal year, and September and October were anything but normal. Harvey, Irma, Marie and other storms brought misery to humans on an almost unimaginable scale, but wildlife suffered, too. Hurricanes barrel into islands and coastlines at the same time as migrating birds are winging toward their winter homes.

How can small, lightweight beings survive winds of up to 185 miles per hour, rains that bucket down for days and widespread flooding? Birds have had to deal with hurricanes for eons, and have developed ways to deal with them. They may either shelter in place, like that hummingbird, leave the area like the meadowlark or fly ahead of or even into the storm.

"Birds can be very resilient in the face of threats if their population is strong, there's ample habitat and they are able to move among locations before and after storms pass," says Andrew Farnsworth, a researcher at the Cornell Lab of Ornithology.

That's the good news, reassuring to anyone who feared that birds caught in "Hurricane Alley" this fall had been completely wiped out.

In storms' aftermath, many trees won't survive saltwater surges, landscapes denuded by high winds leave no options for food and shelter and wrecked sewage systems and damaged refineries fill air, land and water with pollutants.

Hurricane Harvey hit Texas' Aransas National Wildlife Refuge hard, leaving murky water and bare trees and shrubs in its wake. Aransas is the only place in the world that the critically endangered migratory flock of whooping cranes, numbering about 330 adults, spends the winter.

No one yet knows how this altered landscape will affect them.

After storms ripped into the Caribbean, an organization called BirdsCaribbean reported that hummingbirds were starving, unable to find nectar in denuded plants. Hummingbird banders along the U.S. Gulf Coast reported a similar scenario.

In Cuba, an island with 26 kinds of birds found nowhere else in the world, from the Cuban pygmy owl to the Zapata sparrow, naturalists and birding guides fretted as massive storms rolled through. The north side of Cuba took the brunt of Hurricane Irma's devastation, but early reports indicate many birds survived.

Larger birds may survive by working with a hurricane's energy. A crow-sized shorebird called a whimbrel fitted with a tracking device became famous in 2011 for flying into a major tropical storm. The same bird had just settled on a Caribbean island when Irma hit this year, but a local naturalist located the whimbrel several days later, busily feeding on the shoreline.

This has been an unusually destructive hurricane season, and while experts say that the warming of the Earth doesn't cause such storms it is a factor in making them more intense and longer lasting.

And hurricanes aren't the only threats that birds face. We humans have been altering the environments birds need as stopovers during migration. Think of all the development along coastlines, places that traditionally offer food and shelter to migrants as well as local birds.

"The issue is one of how resilient birds can be, given so many rapid changes happening to [eco]systems," says Cornell's Farnsworth. "Birds evolved with these habitats, but when we lose pieces of these systems, much less flexibility is possible."

We won't know for years if enough endangered Puerto Rican parrots survived Maria to keep the population viable, or the status of a rare warbler on the island of Barbuda. The Audubon Society reports that Irma wiped out all 44 Everglade snail kite nests around Florida's Lake Okeechobee, a huge hit on an already endangered species.