Magnificent Frigatebirds

I went down to St. Marks NWR this morning. Just after I got to the refuge a friend flagged me over and said that she had seen Magnificent Frigatebirds at the coast. When I got there, six frigatebirds were suspended in the air above the lighthouse riding a strong onshore wind that was blowing about 30 mph. These are large seabirds with a seven-and-a-half-foot wingspan. They are masters of the air. I watched for twenty minutes as they floated effortlessly in the sky, sometimes lower, sometimes higher, until they began to drift away.

These frigatebirds were artifacts of Hurricane Sally. We often get frigatebirds associated with strong storms. They are ephemeral, briefly at the coast and then gone back out to sea. They’re gone now, but there may be much to see at the refuge in the coming weeks. We are entering a key point in Fall migration.

Fall migration is a vast tidal movement of over five billion birds. It begins in July as the Southernmost breeding songbirds join Arctic-nesting shorebirds moving South to Caribbean islands and South America. It builds as a long slow swell when birds breeding to our North finish their breeding cycle and begin to head South. It reaches a crescendo in late September and into October when 130 species of migrants move into, through or over St. Marks NWR. Then, it drops off quickly in November as the last of our winter birds show up and the last through-migrants move past. By mid-December it’s over. It’s possible that as many as 15 million birds will cross the refuge during Fall migration. Most will just fly over.

It doesn’t proceed smoothly. There are waves of migrants that move on favorable winds and currents within the flow as birds swing around the Western end of the Gulf of Mexico or funnel down through the Florida peninsula intent on reaching their preferred wintering grounds. Other waves of migrants take a more direct route, launching across the waters of the open Gulf.  

It takes place mostly at night, but there are diurnal migrants too: swifts, swallows, hummingbirds, hawks, storks and geese. The nocturnal migrants start moving within the first hour after nightfall, as warblers, thrushes, orioles, tanagers, wrens, shorebirds and ducks take flight. Birds are flying at all altitudes. Many of the songbirds fly between 500 and 3,000 feet, but the stronger flyers, shorebirds and ducks, are a mile up and some even higher.

Songbirds are making hops of several hundred miles and most will land before sunrise to feed before moving on again. Some make a 600-mile jump across the Gulf and fly all night and into the next day. A few species of shorebirds proceed in jumps of thousands of miles, which may keep them in the air for several days after which they will stop and feed for up to a week before making their next jump.

You can observe Fall migration by watching silhouetted birds pass by a full moon or listening for flight calls filtering down from above on a still night. On crisp October mornings you can sometimes see late flyers coming down to land. On some mornings the woods are suddenly full of birds that weren’t there yesterday and have arrived overnight. On other mornings woods that have been active for days are suddenly quiet as birds leave in the darkness to continue their journey. Some daytime migrants spend the night in marshes and just before sunrise you can watch Eastern Kingbirds, Barn Swallows and Red-winged Blackbirds boil out of the marshes in the hundreds or even thousands and fly off, all in the same direction. Swirling kettles of migrating Turkey Vultures passing through the refuge sometimes contain surprises, a Peregrine Falcon or a Northern Harrier. 

The weather is changing. Fall wildflowers are coming out. It’s a good time to come down to St. Marks.