Star Billing - characteristics of the roseate spoonbill and threats to its food supply Everglades National Park

National Wildlife, April-May, 1999 by Les Line

With flashy colors, specialized bills and unusual feeding techniques, roseate spoonbills command attention

With bills submerged, in light that is painful to unshielded human eyes, a delegation of shockingly pink birds might be seen on any given winter day traversing a mangrove-edged flat on Florida Bay. The point of the exercise, of course, is to forage. But exactly what those bills are doing in that murky water has been until recently one of ornithology's tantalizing mysteries.

Early settlers in the Keys confused this long-legged wading bird with flamingos, which sometimes wandered over from the West Indies. However, as Audubon found when he went looking for nonexistent flamingo nests in the 1830s, this is the roseate spoonbill, which Roger Tory Peterson called "one of the most breathtaking of the world's weird birds."

Breathtaking because of its plumage, which is startling enough year- round but erupts in carmine and orange during the breeding season, accounting for the folk name "flame-bird."

Weird because of the 6-inch-long appendage that led to another colloquialism, "banjo-bill." Its full function was only conjecture until an aerospace engineer and a biologist recently attached a skull to a bicycle wheel and rewrote the chapter on spoonbill feeding tactics.

Peterson also remarked that the roseate spoonbill--a Neotropical species that can be found from Argentina to the Gulf Coast of the United States--was virtually wiped out during the plume-hunting era. "If it were not for the fact that some spoonbills still survived south of the border," he pointed out, "the species surely would have followed the passenger pigeon and the Carolina paroquet into the void of extinction." (Five other spoonbill species--all with pure white plumage--are found from Europe and Africa to Australia.)

Though they were easy targets, roseates weren't usually hunted for the millinery trade, since the pink feathers quickly fade. Rather, the slaughter of egrets for their nuptial plumes caused spoonbills, which shared the colony sites, to desert their nests. The plume frenzy, which began in the late 1800s, ended around 1920 with only two dozen breeding pairs of roseate spoonbills surviving on the entire Gulf Coast, where once there were thousands. Today, the species' status on the breeding islands of Texas and nearby Louisiana apparently is secure, due in large part to decades of protection from poachers by National Audubon Society wardens who patrolled colonial bird nesting islands.

Yet the roseate spoonbill's presence today on Florida Bay seems almost as tenuous as it was in 1941. That summer, Robert Porter Allen, who practically invented the science of conservation ornithology, reported to the Audubon Society that the species' recovery there was going poorly and he didn't know why. The bird's troubles, in retrospect, may have been due to the fact that spoonbills were still being shot for food in the late 1930s; back then their nesting ground was too remote for law enforcement. But by the mid-1950s the breeding population was steadily building toward a peak of 1,254 nests in 1972.

The present threat is an indirect one: the degradation of the mangrove ecosystem because of freshwater diversion from the Everglades to farms and burgeoning coastal cities--or straight into the Atlantic Ocean during the rainy season. "There has been a steady decline in spoonbill nests on Florida Bay," says Jerry Lorenz, a University of Miami graduate student who has been studying the problem for the last nine years. Lorenz estimates the present number at only 400 breeding pairs. Another 185 pairs nested last winter at National Audubon's Florida Coastal Islands Sanctuary in Tampa Bay, and Lorenz says many probably were forced to use secondary habitat because of the poor conditions around Florida Bay. "This place is falling apart," he laments.

But we're getting ahead of the remarkable spoonbill bill.

Think of a bird's bill--a horny yet flexible extension of its jaws--as a "hand" its owner uses for nest-building, preening and sometimes as a weapon. Above all, the bird uses the bill to catch and handle food. And its shape and size often reflects specialized foraging tactics. For example, ibis, which are in the same family as spoonbills, have long, slender and decurved bills adapted for probing in mud. The roseate's bill, on the other hand, is an inch or so wide just under its eyes, narrows in the middle, widens to 2 inches near the tip--and is decidedly flat.

Ibis and spoonbills are both tactile foragers: That is, the bill snaps shut as a reflex action when contact with prey stimulates nerves at the tip. The spoonbill usually feeds in water no higher than its knees, and it is able to breathe while doing so through nostril slits located high on its bill.

In uncommonly lyrical prose, Allen described how the bill sweeps "from side to side in wide semicircles, the mandibles slightly parted, the tips digging gingerly into the surface film of the soft bottom, beneath waters that are nearly always opaque. Delicate, sensitive to the small wrigglings and the darting, skittish movements of fish or prawn a quarter of an inch in length or of insects of even lesser dimensions, this keen, responsive instrument must serve as both eyes and hands." He was mostly right.