Slow start to spring migration
I was on the outer levee at St. Marks National Wildlife Refuge when I saw a Northern Flicker sitting on the bare remains of an old cedar tree that stuck up out of the salt marsh. It was an odd place to find an ant-eating woodpecker. As I watched, it took off and flew West. It will likely move up some coastal river valley and work its way North, another migrant heading home.
Spring Migration starts slowly, but 360,000 birds have already migrated across the refuge this month.
Most kept going, but a few stopped to rest and some were summer residents coming back.
Come April, migration will be a sizzling affair with a half million birds moving on nights with favorable winds. By the time migration is over in June, almost 10 million birds will have crossed the refuge.
Spring migration in early March can be a subtle affair. It is mostly birds sneaking out or sneaking through with only a few new visible arrivals.
Winter birds are mostly nocturnal migrants and leave in the night with no fanfare. It’s easy to see that the ducks are gone. It can be harder to notice that you’re not seeing Orange-crowned Warblers anymore.
Then, there are the bird species that are resident at the refuge, but that also migrate through, many of which are March migrants. Separating them from the locals can be a problem.
The Common Yellowthroats and Ospreys that pass through the refuge in March look just like our resident birds. If you see more on some days, it is only a guess whether they’re migrants or just a consequence of birding luck.
Behavior sometimes helps you see which birds are migrants.
Migrant Anhingas stopping to feed in a wetland are indistinguishable from the refuge’s local Anhingas.
A flock of Anhingas circling overhead are migrants using the rising air of a thermal to gain altitude. They will effortlessly glide downwind, slowly losing altitude and, then, look for another thermal and repeat the process. It is a slow but efficient way to migrate that is employed by raptors, vultures and storks.
As March progresses, migration will become more apparent as most of our summer birds return.
We will soon be seeing Prothonotary Warblers, Red-eyed Vireos and Acadian Flycatchers.
They follow leaf out, which tracks the availability of newly-emerged insects.
By April, migration will become obvious as the major rush occurs and Scarlet Tanagers, Baltimore Orioles, Blackpoll Warblers and Cape May Warblers come through.
Spring migration at St. Marks National Wildlife Refuge will occur, with or without you, but come down anyway and bear witness to an annually recurring miracle.
Don Morrow can be reached at firstname.lastname@example.org.