Hilton Pond Center, smack dab in the middle of the Carolina Piedmont, doesn't sit in a major flyway, so we never get big numbers of Neotropical migrant birds that occur along the coast or mountain ridges in spring and fall. Nonetheless, we see a nice assortment of migratory species, some of which stop temporarily after hitting our mists nets. Late April is an interesting time because winter birds are lingering prior to a trip back north, the Neotropicals are coming through, and our year-round residents are jockeying for mates and territories. During the last ten days in April we banded 15 species--far fewer than what might be caught at a migratory hotbed--but just enough for us to have time to study every individual and, in some cases, take a few photos by which to remember it. We hope you enjoy the following gallery of some of our new finely feathered friends--migrant and otherwise--each of which has a numbered band that eventually may tell us interesting things about migration, longevity, and site fidelity.

All text & photos © Hilton Pond Center

We always know when spring migration has begun because we start getting phone calls from folks who breathlessly report a sparrow-sized blue bird at the feeders that's "NOT a bluebird." It's then we know for sure Indigo Buntings have arrived in the Carolina Piedmont. To our eyes, the adult male (above) is one of the most attractive birds in North America, with feathers in shades of blue that go far beyond indigo and nearly defy description. We've also seen these Neotropical migrants on our hummingbird study site in Guanacaste Province, Costa Rica, where most males sport non-breeding plumage--a calico mix of brown and blue.

Although they're present year-round at Hilton Pond Center, we typically see Black-and-white Warblers during spring migration and the breeding season. The adult male (above) fits his name perfectly, with white and black the only colors in its plumage, bill, legs, and eyes. (In the photo above, a pinkish cast on the bird's lower mandible is a reflection from the bander's hand.) Females and juveniles look very much like males but have a much grayer cheek patch. We also knew the bird above was a male because he had a well-developed cloacal protuberance--an indication he's probably a local breeder. A second male Black-and-white Warbler we netted this week did not have the protuberance and was carrying a little body fat, so we suspect he was a migrant just moving through.

Because they're brown and have spotted breasts, a beginning birder sometimes confuses Brown Thrashers with thrushes, but if you've ever been eyeball to eyeball with the former the differences become obvious. An adult Brown Thrasher (above) has a long tail and brilliant yellow eyes--irises in juveniles are a muddy brown-gray--and a long, stout, slightly decurved bill it doesn't hesitate to use on an unwary bander. We've also learned thrashers are quite vocal in the hand and almost always defecate in our direction--which is why we always aim them away from data sheets and the computer during the banding process.

The Chipping Sparrow (above) is another species present all year but whose numbers increase dramatically at feeders in late winter. This small sparrow is at its finest when it acquires its breeding plumage in April, when its brownish cap changes to bright rust and its dingy white facial feathers are replaced by clean white ones. Sexes look alike in this species, but the breeding male gets a remarkably large cloacal protuberance as his hormones rise in the spring. This species nests every year at Hilton Pond Center--usually a few feet off the ground in Eastern Red Cedar trees where the small, tidy nest is typically lined with a soft bed of horsehair.

Unlike our year-round Chipping Sparrows, the White-throated Sparrow occurs at Hilton Pond Center only during "winter," showing up in early October and usually departing by late April. (Our spring banding date of 27 May 2003 was remarkably late, but the species actually has been seen rarely in South Carolina even in mid-summer.) Many observers think dingy-colored White-throated Sparrows (above right) are either females or juveniles that haven't yet acquired breeding plumage, but this isn't correct. Juveniles ARE paler, but there are actually two different color morphs among adult White-throated Sparrows--bright vs. tan. Note that both morphs still have unmarked throats and yellow lores characteristic of the species. Curiously, on their northern breeding grounds females appear to prefer less colorful males as prospective partners--possibly because brighter males try to mate with several females and have less time to pay attention to paternal duties.

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During winter, male and female American Goldfinches look pretty much alike, with drab olive-green plumage, dark wings, and brownish bills. When spring arrives, both sexes go through a serious transformation, bringing in yellow body feathers that are much brighter; males (above right) get a jet black forehead. In both sexes, a vernal increase in testosterone causes carotene pigments to be laid down in the bill--beginning at the base and moving distally--and the mandibles acquire a pumpkin-orange color (above). In autumn, testosterone production decreases, carotene deposits cease, and melanin pigment causes the bill to again turn brown. Young of the year, having no significant testosterone, show drab plumage and brown bills until their first spring.

Who can forget that old grade school joke about "What's black and white and red/read all over?" Depending of how one spells red/read, answers can vary from "an embarrassed zebra" to "the daily newspaper," but after this week we'll go with "an adult male Rose-breasted Grosbeak." This big-billed bird is always a delight when it shows up in spring at the feeder, where it can consume sizeable amounts of sunflower seed. Unfortunately, the nattily plumaged grosbeak doesn't very long stay at Hilton Pond Center, continuing instead to breed in the North Carolina mountains and points northward.

Less obvious than the male Rose-breasted Grosbeak is the female (above), who's brown and white and NOT red all over and looks like some sort of giant sparrow. (Actually, females do have a little orange on them but it's under the wing, below right, and seldom seen except by bird banders. In the male these underwing feathers are rosy like his breast.) The grosbeak's bill is already formidable because of its size, but the lower mandible also has a "tooth" on it that enhances biting power. Sunflowers seeds are no match for this powerful tool; in fact, grosbeaks are even able to open cherry pits. During breeding season they feed their offspring all sorts of wild fruits, along with protein-rich caterpillars and adult insects.

Again, Hilton Pond Center doesn't get huge numbers of spring migrant birds, but we enjoy those that do pass through or stay year-round. Our enjoyment is enhanced by the privilege of capturing and banding a few of these AVIAN visitors to our yard--migrant or otherwise--and sharing our photographs with HUMAN visitors to our Web site. Let us know if you like them, and Happy Spring!

"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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