I’ve been watching the news lately, and it seems we are having some hurricanes. A friend saw a report on television alleging that migrating birds trapped in a tempest will find sanctuary in the eye of the storm. True, he wondered? I prefer to be asked questions for which I already know the answer. Alas, sometimes I have to do actual research.
Getting caught in a storm is bad, especially for birds migrating over water. There’s no place to land and wait it out. Logically, all birds are descended from earlier birds that didn’t drown, so somehow they’ve got it figured out. Mostly. No plan is foolproof, but birds do have several defense strategies.
We know they can sense changes in barometric pressure. As a storm approaches and the barometer falls, many birds react by feeding voraciously. You might have seen this at your own feeders before a blizzard. The white-throated sparrow is a common Maine breeder. Earlier this decade, researchers placed some sparrows into a hypobaric chamber and manipulated pressure. When the barometer was steady or rising, not much happened. But when the chamber simulated low pressure, the sparrows reacted like I do at an all-you-can-eat buffet.
It’s known that birds adjust the timing of their migratory flights based on changing air pressure. If they sense a storm, they just don’t leave. After the storm has passed, northwest breezes typically follow, and these winds are ideal for migration. A veritable flood of birds left Maine this week.
Some birds fly into storms deliberately. Whimbrels are large shorebirds that breed near the arctic and winter in South America. In 2011, a radio-tagged whimbrel named Chinquapin flew directly into Hurricane Irene, when it was still a Category 3 storm over the ocean. The bird made little progress flying into the wind but persevered. Once it had passed through the eye, the powerful winds flung him southward at an incredible 90 mph. As if fired from a slingshot, he arrived in South America in record time. However, biologists tracked a second bird that tried the same trick and died.
We know that flocks of birds caught in a hurricane will stay aloft within the eye of the storm and try to ride it out. Most recently, radar detected large flocks within Hurricane Irma. Of course, the problem is that the birds have no choice but to go where the storm in going. In 2005, a large flight of chimney swifts got caught up in Hurricane Wilma and rode the storm all the way to Europe. Sadly, they were so exhausted that most perished upon making landfall. The following year, breeding bird surveys in Quebec detected only a third the usual number of nesting swifts.
The redirection of migrating birds because of a storm does produce some unusual sightings. A fork-tailed flycatcher has been spending this week at Maine Audubon headquarters in Falmouth. This flycatcher has an impossibly long tail, and normally inhabits grasslands from southern Mexico through Argentina. It is a well-known wanderer, and individuals show up in North America annually. Another was seen in Maine five years ago. These meanderings are probably the result of navigational failures rather than storms, but we really don’t know how they got so far from home. One thing is for certain: If the Falmouth flycatcher wanted to avoid attention, the last place it should have settled was an Audubon sanctuary.
The brown booby is a large, plunge-diving seabird, similar to the northern gannets that are swirling off our shores right now. You would not be surprised to see one land on a fishing boat in the Caribbean. You would be surprised to see the one that landed on a lobster boat in the Gulf of Maine this week. It loafed on the deck for half an hour before flying off.
The effect of birds being carried by hurricanes might not be very noticeable if all tropical storms stayed in the tropics. But for those tempests that veer north, results can be astounding.
Hurricane Irene bent northward in 2011 and spread destruction all the way to Vermont. In the days that followed, at least a dozen white-tailed tropicbirds popped up from Delaware to New Hampshire, apparently carried away from their home grounds in Bermuda. Numerous subtropical species also appeared in New England, including pelicans, frigatebirds, storm-petrels, and at least three types of southern terns. Ocean birds were found on inland lakes.
The winds have been busy lately. Stay alert for weird strays.
Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at firstname.lastname@example.org.