How Hurricane Helene gave us another glimpse into fall bird migration

George Walter

Photo by Jill Severn

By George Walter

Have you read enough about Hurricane Helene and all its impacts? Here’s another story about the hurricane that might surprise you. September and October are peak months for the southward migration of many North American breeding bird species, and Hurricane Helene hit the southeastern United States right in the middle of this critical time.

In the fall we see many flocks of ducks and geese flying overhead, but most smaller birds migrate invisibly at night, and until recently ornithologists knew relatively little about these smaller songbirds—warblers, vireos, and hummingbirds, for example.

From ordinary observations, ornithologists know that there are three primary migration corridors or flyways. The Atlantic Flyway generally follows the east coast, with birds either wintering in Florida or flying from there to the Caribbean and Central and South America. The Central Flyway runs through the middle of the continent, with birds crossing Texas and flying into Mexico. The Pacific Flyway follows the west coast.

In recent decades, ornithologists have expanded their knowledge and developed research tools to better document these migrations. The primary instrument is radar, both existing weather radar and stations specifically designed to detect and count migrating herds. These mass detections are aided by tagging small numbers of birds with small sonar transmitters.

The Cornell Lab of Ornithology (the same group that creates the Merlin bird app) compiles all of this data into a report that allows real-time tracking of migrations. This data and an hour-by-hour presentation can be found on the BirdCast website. The BirdCast maps for the days before Helene through early October show how migratory birds adapted to the hurricane. As the hurricane hit Northwest Florida on the evening of September 26th and 27th, huge flocks of migrants headed west, following the Central Flyway. Hurricanes in the Northern Hemisphere rotate counterclockwise and the migrants sailed on the outer hurricane winds. In fact, radar data shows that migrants noticed the approaching hurricane and diverted westward several days in advance.

This information expanded what little we really know about the migratory abilities of these small birds (and most of them are small songbirds, although the total also includes ducks, geese, and shorebirds). And the numbers! On October 2nd^ndOn the day I wrote this, the highest number of migratory birds counted was 650 million. On other nights, peak numbers vary, but 750 million birds per night are not uncommon.

You should check out this BirdCast site. Although I have used it to monitor hurricane impacts, it also tracks migration patterns and timing in the Pacific Northwest or elsewhere. Our migration density in the Northwest is modest compared to the Eastern United States. Our peak numbers could reach 5-10 million birds.

Of course, we can also experience migration on site. Last weekend a friend and I were hiking the Chehalis Western Trail when a small flock of Canada geese flew by and made their way to a meadow to graze. And following them were some other geese making strange noises. Their shrill laughter or yelp had nothing to do with that of the Canadians. They were Great white-fronted geese.

These geese are about the size of Canada geese, but are brownish with black spots. They have a bright orange bill with a circle of white feathers and orange legs. Canada geese and clucking geese have black necks, beaks and legs. Snow geese, also seen locally at this time of year, have orange bills and feet but are snow white with black wing tips.

All of these geese enjoy grazing on fresh, green grass, and some of the unusual geese are passing through on their way to their main wintering grounds further south. However, there have been a few white-fronted and snow geese in our Olympic Christmas bird count for many years, so not all of them migrate south for the winter.

Our native small songbirds are gathering in mixed species flocks preparing to leave, and many species have already departed. Reports of swallows, for example, are rare after September. And some of the mixed species flocks encountered may have nothing to do with migration preparation.

Two weeks ago, the same friend reported that her Merlin app recorded eight species of birds in a mixed flock around her as she sat on a bench along the trail. Some were high up in the trees, others were in the bushes near the ground. The herd: Brown Creeper, Red-breasted NuthatchChestnut-backed Tit, Yellow-rumped Warbler, Gold-crowned kingletAmerican goldfinch, Spotted Towhee And Northern Flicker.

What can we make of this group? It initially appears that the birds may have been feeding close to each other by chance. However, many pairs of eyes reaching from the ground to the treetops likely provide collective protection from birds of prey. Since an alarm call of one species benefits all.

For many birders, fall may seem boring – the chorus of spring and summer song is over, but the birds have not yet gathered at our bird feeders. However, a lot happens when we just walk outside and notice it.

George Walter is an environmental program manager in the Natural Resources Division of the Nisqually Indian Tribe. He has also been interested in bird watching for over 40 years. He can be reached at [email protected]

Photos for this column were provided by Liam Hutcheson, a 17-year bird watcher and avid photographer from the Olympia area.