Spring Migration
Spring Migration is coming! Every spring over 3 billion birds move north into the United States and Canada after spending the winter in Central and South America, Mexico, and the Caribbean. These extraordinary flights of birds across the continent generally occur between February and June, through what scientists call flyways.
Although these broad pathways of migratory birds have been generalized into the Atlantic, Mississippi, Central, and Pacific Flyways, how closely birds adhere to these corridors depends on the particular species. Some species, such as the mallard, occur across the continent and can be found in all four flyways, while other species, such as the hermit warbler, may be limited to just a single flyway. And then there are species such as the long-tailed duck, in which individual migration patterns can be unpredictable.
Periodically, birds that are usually restricted to a particular region of the country, are sighted in an area they’ve only rarely been observed, if at all. This typically happens during migration, when it’s thought individuals can get shifted out of their traditional flyway by severe weather or other factors. On a trip to Bosque del Apache National Wildlife Refuge, New Mexico, in the Spring of 2021, I was fortunate to observe such an incident of wayward migration. There, I spotted a scarlet tanager, a species that winters in Central and South America and typically summers in the eastern deciduous forests of North America. Only 76 observations of scarlet tanagers in New Mexico have been reported in eBird and of those, only seven were in and around the refuge. This is because scarlet tanagers typically return from their wintering grounds over the Gulf of Mexico through the Atlantic, Mississippi, and Central Flyways.
Scarlet Tanager, Bosque del Apache National Wildlife Refuge, New Mexico, 5 May 2021.
Scarlet tanagers migrate at night, and I saw this bird in the afternoon, voraciously eating insects, presumably preparing for the next leg of its journey. It was not seen again at the refuge after this day.
So this spring, when you’re out hiking, birding, or just enjoying your backyard or local park, look and listen for one of the great animal migrations unfolding around you. The birds will be in their full regalia of breeding plumages and welcoming the return of spring with their enthusiastic songs and behaviors of the mating season. And who knows? You may even see a bird that has wandered out of its traditional flyway!
