The first reports of migrating male ruby-throats in early spring start out few and far between in Louisiana, where reknowned bird bander, Nancy Newfield does her hummingbird research.
Year-Round in Louisiana
"Here in Louisiana we are blessed with having two completely different overlapping seasons and we can have hummingbirds in our gardens 365 days a year," writes Nancy Newfield. How does she know when the first migrating ruby-throat arrives in the spring?
Migrant or Wintering?
Early in the spring, before banding season begins, Nancy keeps a close eye on her feeders to watch for newly arriving migrants. She relies on small visual details to determine if she is seeing a migrant or a winter resident.
"Sparkling and bright" is how Nancy describes the plumage of a migrant male ruby-throat in late winter or early spring. Wintering adult males are still molting. Their wing, tail, and contour feathers will be quite dull by comparison.
The differences between female winter residents and spring migrants are subtle, and difficult to see from a distance. Only bird-banders have the opportunity to capture and examine birds up close.
Banders Get a Close Look
The spring banding season begins in mid-March. During the banding process Nancy examines a hummingbird's general physical condition.
Fat or No Fat
The amount of fat a bird carries helps determine if the bird is a migrant. Nancy uses a regular drinking straw to gently blow on a hummingbird's underside. If there are no fat deposits, the bird is most likely not a migrant.
When Nancy handles a female ruby-throat she looks to see if the bird is carrying an egg. If so, we know she's a local breeder, not a migrant.
Males are more challenging to identify. We use a few 'status codes' - BB = breeding bird; SM = spring migrant; FM = fall migrant. For adult males in March through May, we generally assign SM to those that carry a good bit of visible fat beneath the translucent skin and BB to those that exhibit little or no fat.
In the Spring
It is challenging to determine if the ruby-throats we see in spring are migrants or part of the local population. When researchers, like Nancy, recapture a recently banded bird, it is most likely local. A migrant is heading for its breeding grounds and isn't going to stay in one area for more than a week.