I suppose you’re wondering what hurricanes do to bird migration. Nothing good, I can assure you. But birds have been dealing with hurricanes since the dawn of time. Surely, they have a strategy.
They do, but it’s far from foolproof. Migration is dangerous. Many birds are killed by storms, although many more are killed by cats and collisions. As long as enough birds survive to reproduce, the species will continue.
The big question is not how the birds can survive one hurricane. The big question is how they will deal with the more frequent and severe hurricanes we’re now experiencing.
Some birds are more vulnerable than others. Storms likely have little effect on nonmigratory birds. They typically find shelter. The biggest threats to resident birds are hurricanes that devastate their entire habitat.
The red-cockaded woodpecker nests in old-growth pine forests of southeastern states. Human development throughout their range has isolated populations and depressed their numbers. They’re now endangered. In 2009, Hurricane Hugo flattened the trees in the nation’s second-largest red-cockaded woodpecker colony in South Carolina.
Birds that migrate over land can usually hunker down somewhere, even if they get blown far off course. Most will likely survive. But when a large flock is diverted far from its natural food supply, many may starve before getting back on course.
Seabirds and waterfowl can ride out storm-tossed seas, and many are adept at finding shelter behind islands and other wind barriers. Brown pelicans have demonstrated a particular talent for this. But when a hurricane floods an estuary and stirs up sediment, food can be hard to find for a while.
Songbirds are most endangered by severe storms. If caught over water, they may simply run out of fuel and fall into the sea. The lucky ones that make landfall may be so exhausted that they lack the energy to refuel and resume their journey.
In 2005, Hurricane Wilma surprised a huge flock of migrating chimney swifts, blowing many all the way to Europe. Hundreds were found dead. The next year, only half the normal Quebec population returned to nest.
Many birds migrate across the Gulf of Mexico, either to Caribbean islands or to Central and South America. Storms in the Gulf pose a threat to many species. Ruby-throated hummingbirds, headed for South America, must cross at least 500 miles of open water. It’s likely that the majority of birds caught in a storm won’t make it.
Fortunately, hummingbirds have their own strategy. Rather than leave their breeding grounds in one big wave, they trickle out over two months. One migrating flock might hit a storm, but the majority won’t.
Birds in the interior part of the continent fear crossing the Gulf of Mexico. Here in the northeast, many migrants also must deal with the North Atlantic. Blackpoll warblers are famous for their long-distance flights. They leave the New England coast, fly out to sea, and hope prevailing winds will push them back toward South America.
They can spend three days aloft, and travel 1,800 miles. Hurricanes counteract the prevailing winds, and they can be devastating. It’s likely even worse when a storm comes into the Gulf of Maine and greets them head-on.
Or maybe not. Songbirds also have migration survival strategies. Many can sense a drop in barometric air pressure. Some can hear low frequencies over long distances — the kind of low frequency a hurricane makes from hundreds of miles away.
It’s clear that many species can sense weather trouble coming and adjust their migration schedules. Sparrows are particularly adept at this.
Several days before Hurricane Lee swept up the coast, there was a massive migration wave ahead of the approaching storm. We know, because radar can pick up the migrants. Reports of migrating birds settling down on offshore islands after a night flight also indicated impressive numbers.
When all else fails, strong fliers can sometimes fly above the worst of the storm. They can even fly through it, or within it. If the hurricane makes landfall, they have a fighting chance for survival.
Even weaker fliers have discovered a survival strategy. They can stay aloft inside the eye of the storm, where conditions are surprisingly calm.
Regardless of what strategy different birds use, one thing is for certain. When stuck in a storm, the birds are going wherever the storm is going.
Experienced birders know to look for unusual birds. far out of their normal ranges, after every big storm event.
During fall migration, anything can happen.
