The outfit of the Black-bellied Plover we see is a bit drab compared to the breeding plumage of spring and summer. (immediately below, left)
Have you noticed at the supermarket or at the mall, all of the shoppers are going about their business dressed appropriately in comfortable presentable clothes, not too flashy or dressy, but completely suitable for their current shopping activity. But those same shoppers, when dressing for a date, or the beginning of any type of courting activity, will get all dolled up in an outfit designed to present themselves in the best appearance possible. Thus, one outfit to run to the store for a gallon of milk; but a much more fancy and elaborate outfit to go to the Prom.
With birds, the “shopping at the mall” outfit they sport is called “basic” plumage. Birds wear that plumage most of the year, changing into their “alternate” or “prom” outfit in those few short months when they engage in the courting process to prepare for mating and the serious business of breeding and perpetuating the species. In Florida, in the winter time, when many species follow the human “snowbirds” south for the winter ( or is it the other way around, the humans following the bird “snowbirds” south?), we are treated to birds in their basic, more nondescript, visit-the-mall, plumages. In New Jersey, in the spring while on migration, we are treated to birds in their alternate, dressier, going-to-the-prom, plumages. Sometimes, as with humans, the difference is dramatic.
Four common species, found in the winter in Florida, are the Black-bellied Plover, the Dunlin (right), the Ruddy Turnstone and the Sanderling. A birder, viewing any one of these four species in Florida in the winter in their basic or shopping mall plumage, would never suspect that the same species, in its alternate or prom plumage, could be transformed so dramatically. Unfortunately, we are not generally privileged to observe their prom plumage in Florida, but farther north in New Jersey, in May, for a few short weeks until they head farther north for the breeding season, they can be seen in all their best feathered finery.
On field trips in Florida I am sometimes asked, “Where does the Black-bellied Plover get its name?” This is quite a legitimate question from a Floridian who is never treated to the breeding “alternate” plumage, which, when only observed farther north, makes the name obvious. The Dunlin, with its slightly down-curved bill, was formerly called the “Red-backed Sandpiper” which referred to its alternate or breeding plumage, not the basic plumage we see in Florida. The Sanderling probably gets its name from its habit of running back and forth on sandy beaches, not its plumage; and the Ruddy Turnstone, which is not at all “ruddy” in the winter, gets its name from its practice of over-turning small stones while searching for food that might be hiding there.
So the next time you go grocery shopping and see fellow customers comfortable in their shorts and tee shirts, remember that those same customers are just as likely to get all decked out in very dressy finery when getting ready to go a-courting. Same thing is true with most bird species: very plain basic garb for everyday taking care of business, but once a year, for several weeks, a transformation into a remarkable change in appearance, that it’s not surprising that some birders may think that they are a completely different species. Come to think of it, I have seen some of my friends transform into virtually different people when they have made the effort to really put forward their most attractive appearance. And don’t even mention how good they can look for their wedding.