Have you had enough reading about Hurricane Helene and all its impacts? Here’s another story about the hurricane, and it may surprise you. September and October are the peak months for the southern migration of many North American breeding bird species, and Hurricane Helene struck the southeastern U.S. right in the middle of this critical period.
We see many flocks of ducks and geese flying overhead in the fall, but most of the 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 ornithologist have known that there are three primary migration corridors, or Flyways. The Atlantic Flyway generally follows the east coast with birds either wintering in Florida or launching across from there to the Caribbean and Central and South America. The Central Flyway flows across the mid-continent, with birds crossing Texas and flying into Mexico. The Pacific Flyway follows the west coast.
In recent decades ornithologists have built upon their knowledge by developing research tools to better document these migrations. The primary tool is radar, both existing weather radar and stations created specifically to detect and count migrating flocks. These mass detections are supported by tagging a small number of birds with small sonar emitters.
The Cornell Lab of Ornithology (the same group that produces the Merlin bird app) puts all these data together in a report that allows for real time tracking of migrations. You can find these data and an hour-by-hour presentation at the BirdCast website. The BirdCast maps for pre-Helene days through early October demonstrate how migrating birds adapted to the hurricane. When the hurricane struck NW Florida on the evening of September 26-27, huge migrating flocks were diverting to the west and following the Central Flyway. Hurricanes in the northern hemisphere rotate counterclockwise and the migrants were riding the outer hurricane wind. In fact, the radar data show that migrants were detecting the approaching hurricane and diverting to the west several days in advance.
This information increased what little we really know about how these little birds’ migration abilities (and most of them are little songbirds, although the overall numbers include ducks, geese and shorebirds). And the numbers! On October 2nd, the day I wrote this, the peak number of migrating birds counted was 650 million. Other nights vary in peak numbers, but 750 million birds per night is not unusual.
You’ll want to check out this BirdCast site. Although I was using it to see hurricane impacts, it also tracks migration patterns and timing in the Pacific Northwest or elsewhere. Our northwest migration densities are modest compared to the eastern U.S; our peak numbers may reach 5-10 million birds.
Of course, we can also witness migration locally. This past weekend a friend and I were walking the Chehalis Western Trail when a small flock of Canada Geese flew over, heading for a grassy field to graze. And following them were some other strange-sounding geese. Their high-pitched laughing, or yelping, was nothing like the Canadas. They were Greater White-fronted Geese.
These geese are about the size of Canadas, but brownish with black splotches. They have a bright orange bill with a circle of white feathers and orange legs. Canada and Cackling Geese have black necks, bills and legs. Snow Geese, also seen locally at this time of year, have orange bills and feet but are snowy white with black wing tips.
All these geese like to graze on fresh green grass and there are a number of the unusual ones passing through now on their way to their primary wintering grounds further south. However, many years our Olympia Christmas Bird Count has a few white-fronted and snow geese, so they don’t all go south for the winter.
Our local small songbirds are gathering in mixed-species flocks, getting ready to depart, and many species have already left. Reports of swallows, for example, are rare after September. And some of the mixed species flocks one encounters may have nothing to do with migration preparation.
Two weeks ago, this same friend reported that, as she sat on a bench by the trail, her Merlin app records eight species of birds in a mixed flock all around her. Some were high in the trees, and some were in the bushes near the ground. The flock: Brown Creeper, Red-breasted Nuthatch, Chestnut-backed Chickadee, Yellow-rumped Warbler, Golden-Crowned Kinglet, American Goldfinch, Spotted Towhee and Northern Flicker.
What can we make of this group? It seems at first that the birds may have been feeding near each other by chance. However, many pairs of eyes, located in from the ground to the tops of trees, likely offers shared protection from avian predators. Thus, as an alarm call from one species benefits them all.
For many bird watchers the fall may seem boring – the chorus of spring and summer singing is over, but birds have not yet gathered at our bird feeders. However, there’s a lot going on if we just get outdoors and notice.
George Walter is the environmental program manager at the Nisqually Indian Tribe’s natural resources department; he also has a 40+ year interest in bird watching. He may be reached at george@theJOLTnews.com
Photos for this column are provided by Liam Hutcheson, a 17-year-old Olympia area birder and avid photographer.
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