Back on the central Florida prairie, Oteyza points an antenna toward the aviary. This is the song of North America's most endangered bird. For NPR News, I'm Amy Green on the central Florida prairie. The group is comprised of researchers, land managers, and conservationists including the Florida Fish and Wildlife Conservation Commission, the Florida Park Service, the Department of Defense, the U.S. Our mission is to conserve and restore natural ecosystems, focusing on birds, other wildlife, and their habitats for the benefit of humanity and the earth’s biological diversity. “We consider this the most endangered bird in the continental United States and worthy of extra efforts,” they wrote. GREEN: Then the researchers hang back 300 feet to wait and watch as the birds join the world's last population of Florida grasshopper sparrows in the wild. The counts of singing males at Kissimmee Prairie declined from 150 a decade ago to only 21 in 2011, to only 14 in 2012. OTEYZA: By raising them in captivity, we increase the chances that they survive until they become independent and then release them after that. The Avon Park Bombing Range sub-population dropped from about 130 singing males in 1999 to only 10 in 2004. The agencies are releasing the birds in small groups. SCHNEIDER: You start to watch them closely. Prioritize sparrow habitat on private lands for protection. We are calling on the Florida Park Service and FWC to match our financial commitment by funding two other additional temporary staff on their lands, respectively, to assist with prairie-wide habitat management, sparrow, and fire ant surveys. GREEN: The releases are proceeding despite opposition from the first researchers to breed the sparrows. Florida Grasshopper Sparrows are extreme habitat specialists; for successful nesting they require treeless dry prairie burned every two years. He's at least 7 years old this year, and he's still doing his thing. You see how intricate their plumage is. Scientists estimate that South Florida’s grasslands, known as dry prairie, once covered almost three million acres. Since May, state and federal wildlife agencies have released more than 70 captive-raised Florida grasshopper sparrows here, itself a vanishing landscape not far from Walt Disney World. SCHNEIDER: We transplanted a lot of native grass, and that's all and growing really, really well inside. Audubon encourages the addition of private properties reported to host sparrow populations to the Everglades Headwaters NWR via full-fee acquisition or conservation easements. GREEN: He says so far, the released birds appear to have survived. The genus Ammodramus contains nine species that inhabit grasslands and prairies. You see how clever their interactions are with each other and with their neighbors. Accuracy and availability may vary. It’s the least you can do. That's the head scratcher: What's wrong?". Your support will power our science, education, advocacy and on-the-ground conservation efforts. Spread the word. BECKY SCHNEIDER: It's made of hardwired cloth, which is basically mesh, but, you know, a kind of cage material. There are some flowers blooming in there, too. Florida's birds and wildlife need your time and energy. The group’s short-term emphasis: Manage the sparrows’ habitat to the best standard possible while mounting an intensive research effort examining threats like disease, genetics and fire ants. Some train binoculars and scopes on the aviary. PAUL REILLO: If this causes high rates of mortality, then the last thing we want to do is expose birds that don't have it to it because it could kill them. GREEN: They open the aviary by removing the panels at either end. OTEYZA: We won't really know until next year based on how many birds return because they're so cryptic. The Florida grasshopper sparrow (Ammodramus savannarum floridanus) is endangered. GREEN: That's Juan Oteyza of the Florida Fish and Wildlife Conservation Commission. On the tracts where dry prairie remains, the Florida Grasshopper Sparrow is best seen in spring and summer when males perch atop shrubs and sing their grasshopper-like songs to attract a mate. Advance critical research needed to understand the cause of the sparrow’s decline. Ironically, the Florida Grasshopper Sparrow is not Endangered because of the harshness of its habitat, but because of the habitat’s loss. Audubon is urging funders to support proposals from our academic and research partners to get to the bottom of this prairie mystery. Show your love of birds today. You see how beautiful their song is. One of four subspecies of Grasshopper Sparrows in North America, the Florida Grasshopper Sparrow does not migrate, living here year-round (endemic). This text may not be in its final form and may be updated or revised in the future. Amy Green of member station WMFE reports. Perhaps the most endangered bird in the continental US, few people have seen or even heard it. Schneider says she's hopeful. Visit our website terms of use and permissions pages at www.npr.org for further information. Schneider and a small group of researchers approach the aviary, stepping through ankle-high vegetation. Grasshopper Sparrow; King Rail; Least Bittern; Least Tern; Long-eared Owl; Northern Harrier; Northern Parula; Peregrine Falcon; Pied-billed Grebe; Piping Plover; Roseate Tern; Sharp-shinned Hawk; Short-eared Owl; Upland Sandpiper; Vesper Sparrow; Butterflies & Moths. At these population levels, genetic problems become a major concern. The bird has been listed as endangered since 1986 and has suffered steep declines in its population since then. (SOUNDBITE OF THE TRAGICALLY HIP'S "THE DARKEST ONE"). Learn how you can become a citizen scientist or a volunteer at one of our nature centers today. In an effort to rescue the species, wildlife managers are, for the first time, releasing captive-raised sparrows in the wild. Fewer than 40 nesting pairs remain in the wild, making the Florida grasshopper sparrow North America’s most endangered bird. And at Three Lakes Wildlife Management Area, last year’s record low of 67 singing males was surpassed this year, with 60 singing males. At an emergency meeting, the Florida Grasshopper Sparrow Working Group outlined a course of action to save this rare subspecies from extinction. Help secure the future for birds at risk from climate change, habitat loss and other threats. Researchers working with him have identified a pathogen that can be lethal to the sparrows. SCHNEIDER: One bird on side 1A flew out on its own too quickly to see any color bands. It is dismissed as a “little brown bird” by those neither patient nor attentive enough to recognize the beauty and intricacy of its cryptic plumage and lifestyle. Then they'll stop until January or February, when the breeding season begins. Schneider says each bird is identified with colored bands on its legs. But why are the sparrows blinking out? Disease, genetic problems, invasive exotic fire ants and other nest predators are all contending hypotheses, but the reality is: no one knows why our public lands are failing these birds. All rights reserved. That year, … Fish and Wildlife Service, University of Florida, University of Central Florida, Archbold Biological Station, Brevard Zoo, White Oak Conservation Center, and Audubon’s Dr. Paul Gray, an expert on the birds and habitat issues of the greater Lake Okeechobee Region. His main concern is disease. Special protocols to facilitate endangered species burns must be developed. They plan to set free another 30 through September. Grasshopper Sparrow; King Rail; Least Bittern; Least Tern; Long-eared Owl; Northern Harrier; Northern Parula; Peregrine Falcon; Pied-billed Grebe; Piping Plover; Roseate Tern; Sharp-shinned Hawk; Short-eared Owl; Upland Sandpiper; Vesper Sparrow; Butterflies & Moths. And unless they're breeding, and it's a male, we won't see them because the males are the ones that come up and perch and sing. In 2012 only one singing male was detected; it is unknown if a female was there to hear him. GREEN: The sparrows are free. AMY GREEN, BYLINE: On the central Florida prairie, the early morning sun shines down on the Saw Palmetto and wiregrass and something else you wouldn't expect - an industrial-looking 60-by-20-foot aviary. The Grasshopper Sparrow is also declining and the species is not on the list of Vermont Endangered Birds. Paul Reillo is the founding director of the Rare Species Conservatory Foundation.