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Birds - Endangered And Threatened U.s. Species

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As of March 2006 there were ninety bird species listed under the Endangered Species Act (ESA) as endangered or threatened in the United States. (See Table 9.1.) The vast majority have an endangered listing, meaning that they are at risk of extinction. Nearly all have recovery plans in place.

The imperiled birds come from many different genera (plural of genus) and represent a variety of habitats. Most are perching birds, sea birds, or shore birds. There are also a handful of other bird types, including woodpeckers and raptors, such as the bald eagle and northern spotted owl.

Just over $103 million was spent on U.S. bird species under the ESA during fiscal year 2004. Table 9.2 shows the ten species with the highest expenditures. The three most expensive species were the red-cockaded woodpecker ($14.1 million), the southwestern willow flycatcher (nearly $12 million), and the bald eagle in the lower forty-eight states ($9.8 million).

Categories of birds found on the list of endangered and threatened species are described below.

Woodpeckers

Woodpeckers belong to the order Piciformes and the family Picidae. They are characterized by their physiology. They have very hard, chisel-like beaks and a unique foot structure with two toes pointing forward and two toes pointing backward. This allows them to take a firm grip on tree trunks and extend horizontally from vertical surfaces. Woodpeckers prefer arboreal habitats, primarily dead trees in old-growth forests. The birds hammer away at the bark on the trees to dig out insects living there. They often form deep cavities in the tree to use as roosting and nesting holes.

RED-COCKADED WOODPECKERS

The red-cockaded woodpecker (Picoides borealis) is shown in Figure 9.1. The bird is named for the red patches, or cockades, of feathers found on the heads of the males. This species is found in old pine forests in the southeastern United States, where family groups—consisting of a breeding male and female as well as several helpers—nest within self-dug cavities in pine trees. Tree cavities serve as nesting sites in addition to providing protection from

TABLE 9.1 Endangered and threatened bird species in the United States, March 2006

TABLE 9.1
Endangered and threatened bird species in the United States, March 2006
Common name Scientific name Listing statusa Recovery plan date Recovery Plan stageb
Akiapola ˋa (honeycreeper) Hemignathus munroi E 10/16/2003 RD(1)
Attwater's greater prairie-chicken Tympanuchus cupido attwateri E 2/8/1993 RF(1)
Audubon's crested caracara Polyborus plancus audubonii T 5/18/1999 F
Bachman's warbler (=wood) Vermivora bachmanii E None E
Bald eagle Haliaeetus leucocephalus T None
Black-capped vireo Vireo atricapilla E 9/30/1991 F
Bridled white-eye Zosterops conspicillatus conspicillatus E 9/28/1990 F
Brown pelican Pelecanus occidentalis DM, E 8/1/1980 F
Cactus ferruginous pygmy-owl Glaucidium brasilianum cactorum E 1/9/2003 D
Cahow Pterodroma cahow E None
California clapper rail Rallus longirostris obsoletus E 11/16/1984 F
California condor Gymnogyps californianus E, EXPN 4/25/1996 RF(3)
California least tern Sterna antillarum browni E 9/27/1985 RF(1)
Cape Sable seaside sparrow Ammodramus maritimus mirabilis E 5/18/1999 F
Coastal California gnatcatcher Polioptila californica californica T None E
Crested honeycreeper Palmeria dolei E 10/16/2003 RD(1)
Eskimo curlew Numenius borealis E None E
Everglade snail kite Rostrhamus sociabilis plumbeus E 5/18/1999 F
Florida grasshopper sparrow Ammodramus savannarum floridanus E 5/18/1999 F
Florida scrub jay Aphelocoma coerulescens T 5/9/1990 F
Golden-cheeked warbler (=wood) Dendroica chrysoparia E 9/30/1992 F
Guam Micronesian kingfisher Halcyon cinnamomina cinnamomina E 9/28/1990 F
Guam rail Rallus owstoni E, EXPN 9/28/1990 F
Hawaii akepa (honeycreeper) Loxops coccineus coccineus E 10/16/2003 RD(1)
Hawaii creeper Oreomystis mana E 10/16/2003 RD(1)
Hawaiian (=ˋalala) crow Corvus hawaiiensis E 12/18/2003 RD(1)
Hawaiian (=ˋlo) hawk Buteo solitarius E 5/9/1984 F
Hawaiian (=koloa) duck Anas wyvilliana E 8/24/2005 RD(3)
Hawaiian common moorhen Gallinula chloropus sandvicensis E 8/24/2005 RD(3)
Hawaiian coot Fulica americana alai E 8/24/2005 RD(3)
Hawaiian dark-rumped petrel Pterodroma phaeopygia sandwichensis E 4/25/1983 F
Hawaiian goose Branta (=nesochen) sandvicensis E 9/24/2004 RD(1)
Hawaiian stilt Himantopus mexicanus knudseni E 8/24/2005 RD(3)
Inyo California towhee Pipilo crissalis eremophilus T 4/10/1998 F
Ivory-billed woodpecker Campephilus principalis E None E
Kauai akialoa (honeycreeper) Hemignathus procerus E 10/16/2003 RD(1)
Kauai ˋo ˋo (honeyeater) Moho braccatus E 10/16/2003 RD(1)
Kirtland's warbler (=wood) Dendroica kirtlandii E 8/11/1978 F
Large Kauai (=kamao) thrush Myadestes myadestinus E 10/16/2003 RD(1)
Laysan duck Anas laysanensis E 11/4/2004 RD(1)
Laysan finch (honeycreeper) Telespyza cantans E 10/4/1984 F
Least Bell's vireo Vireo bellii pusillus E 5/6/1998 D
Least tern Sterna antillarum E 9/19/1990 F
Light-footed clapper rail Rallus longirostris levipes E 6/24/1985 RF(1)
Marbled murrelet Brachyramphus marmoratus marmoratus T 9/24/1997 F
Mariana (=aga) crow Corvus kubaryi E 9/28/1990 F
Mariana common moorhen Gallinula chloropus guami E 9/30/1991 F
Mariana gray swiftlet Aerodramus vanikorensis bartschi E 9/30/1991 F
Masked bobwhite (quail) Colinus virginianus ridgwayi E 4/21/1995 RF(2)
Maui akepa (honeycreeper) Loxops coccineus ochraceus E 10/16/2003 RD(1)
Maui parrotbill (honeycreeper) Pseudonestor xanthophrys E 10/16/2003 RD(1)
Mexican spotted owl Strix occidentalis lucida T 10/16/1995 F
Micronesian megapode Megapodius laperouse E 4/10/1998 F
Mississippi sandhill crane Grus canadensis pulla E 9/6/1991 RF(3)
Molokai creeper Paroreomyza flammea E 10/16/2003 RD(1)
Molokai thrush Myadestes lanaiensis rutha E 10/16/2003 RD(1)
Newell's Townsend's shearwater Puffinus auricularis newelli T 4/25/1983 F
Nightingale reed warbler (old world warbler) Acrocephalus luscinia E 4/10/1998 F
Nihoa finch (honeycreeper) Telespyza ultima E 10/4/1984 F
Nihoa millerbird (old world warbler) Acrocephalus familiaris kingi E 10/4/1984 F
Northern aplomado falcon Falco femoralis septentrionalis E 6/8/1990 F
Northern spotted owl Strix occidentalis caurina T 5/15/1992 D
Nukupuˋu (honeycreeper) Hemignathus lucidus E 10/16/2003 RD(1)
ˋOˋu (honeycreeper) Psittirostra psittacea E 10/16/2003 RD(1)
Oahu creeper Paroreomyza maculata E 10/16/2003 RD(1)
Oahu elepaio Chasiempis sandwichensis ibidis E 10/16/2003 RD(1)
Palila (honeycreeper) Loxioides bailleui E 6/27/1986 RF(1)
Piping plover Charadrius melodus E, T 8/1/1994 D
Poˋouli (honeycreeper) Melamprosops phaeosoma E 10/16/2003 RD(1)
Puerto Rican broad-winged hawk Buteo platypterus brunnescens E 9/8/1997 F
Puerto Rican nightjar Caprimulgus noctitherus E 4/19/1984 F

TABLE 9.1 Endangered and threatened bird species in the United States, March 2006 [CONTINUED] Adapted from "Listed FWS/Joint FWS and NMFS Species and Populations with Recovery Plans (Sorted by Listed Entity)" and "Listed U.S. Species by Taxonomic Group," in Threatened and Endangered Species System (TESS), U.S. Department of the Interior, U.S. Fish and Wildlife Service, March 4, 2006, http://ecos.fws.gov/tess_public/SpeciesRecovery.do?sort=1 and http://ecos.fws.gov/tess_public/SpeciesReport.do?kingdom=V&listingType=L (accessed March 4, 2006)

TABLE 9.1
Endangered and threatened bird species in the United States, March 2006 [CONTINUED]
Common name Scientific name Listing statusa Recovery plan date Recovery Plan stageb
aE=endangered, T=threatened, EXPN=experimental population, non-essential.
bRecovery plan stages: E=exempt, F=final, D=draft, RD=draft under revision, RF=final revision
SOURCE: Adapted from "Listed FWS/Joint FWS and NMFS Species and Populations with Recovery Plans (Sorted by Listed Entity)" and "Listed U.S. Species by Taxonomic Group," in Threatened and Endangered Species System (TESS), U.S. Department of the Interior, U.S. Fish and Wildlife Service, March 4, 2006, http://ecos.fws.gov/tess_public/SpeciesRecovery.do?sort=1 and http://ecos.fws.gov/tess_public/SpeciesReport.do?kingdom=V&listingType=L (accessed March 4, 2006)
Puerto Rican parrot Amazona vittata E 4/30/1999 RD(2)
Puerto Rican plain pigeon Columba inornata wetmorei E 10/14/1982 F
Puerto Rican sharp-shinned hawk Accipiter striatus venator E 9/8/1997 F
Red-cockaded woodpecker Picoides borealis E 3/20/2003 RF(2)
Roseate tern Sterna dougallii dougallii E, T 9/24/1993 F
Rota bridled white-eye Zosterops rotensis E None
San Clemente loggerhead shrike Lanius ludovicianus mearnsi E 1/26/1984 F
San Clemente sage sparrow Amphispiza belli clementeae T 1/26/1984 F
Short-tailed albatross Phoebastria (=diomedea) albatrus E 10/27/2005 D
Small Kauai (=puaiohi) thrush Myadestes palmeri E 10/16/2003 RD(1)
Southwestern willow flycatcher Empidonax traillii extimus E 8/30/2002 F
Spectacled eider Somateria fischeri T 8/12/1996 F
Steller's eider Polysticta stelleri T 9/30/2002 F
Western snowy plover Charadrius alexandrinus nivosus T 5/1/2001 D
White-necked crow Corvus leucognaphalus E None
Whooping crane Grus americana E, EXPN 1/11/2005 RD(3)
Wood stork Mycteria americana E 1/27/1997 RF(1)
Yellow-shouldered blackbird Agelaius xanthomus E 11/12/1996 RF(1)
Yuma clapper rail Rallus longirostris yumanensis E 2/4/1983 F

TABLE 9.2 The ten listed bird entities with the highest expenditures under the Endangered Species Act, fiscal year 2004 Adapted from "Table 1. Reported FY 2004 Expenditures for Endangered and Threatened Species, Not Including Land Acquisition Costs," in Federal and State Endangered and Threatened Species Expenditures: Fiscal Year 2004, U.S. Department of the Interior, U.S. Fish and Wildlife Service, January 2005, http://www.fws.gov/endangered/expenditures/reports/FWS%20Endangered%20Species%202004%20Expenditures%20Report.pdf (accessed February 11, 2006)

TABLE 9.2
The ten listed bird entities with the highest expenditures under the Endangered Species Act, fiscal year 2004
Ranking Common name Listing* Expenditure
*E=endangered, T=threatened
SOURCE: Adapted from "Table 1. Reported FY 2004 Expenditures for Endangered and Threatened Species, Not Including Land Acquisition Costs," in Federal and State Endangered and Threatened Species Expenditures: Fiscal Year 2004, U.S. Department of the Interior, U.S. Fish and Wildlife Service, January 2005, http://www.fws.gov/endangered/expenditures/reports/FWS%20Endangered%20Species%202004%20Expenditures%20Report.pdf (accessed February 11, 2006)
1 Red-cockaded woodpecker E $14,125,085
2 Southwestern willow flycatcher E $11,911,824
3 Bald eagle (lower 48 states) T $ 9,837,240
4 Northern spotted owl T $ 6,980,570
5 Marbled murrelet (California, Oregon, Washington) T $ 5,646,695
6 Mexican spotted owl T $ 5,276,995
7 Black-capped vireo E $ 4,606,463
8 Western snowy plover (Pacific coastal population) T $ 4,530,614
9 Golden-cheeked warbler (=wood) E $ 4,452,326
10 Piping plover (except Great Lakes watershed) T $ 3,489,405

predators. Because red-cockaded woodpeckers rarely nest in trees less than eighty years old, heavy logging has destroyed much of their former habitat. The red-cockaded woodpecker was first placed on the Endangered Species List in 1970. It is currently found in fragmented populations in the southeastern seaboard westward into Texas. Figure 9.2 shows the historical and current distribution of FIGURE 9.1 The red cockaded woodpecker Bob Savannah, artist, "Red Cockaded Woodpeckers," in Pictures/Graphics, Wildlife Sketches, U.S. Department of the Interior, U.S. Fish and Wildlife Service, Undated, http://www.fws.gov/pictures/lineart/bobsavannah/redcockadedwoodpeckers.html (accessed February 15, 2006)FIGURE 9.2 Historic and current distribution of the red-cockaded woodpecker, updated 2002 "Map," in Photos: Red Cockaded Woodpecker: Images, U.S. Department of the Interior, U.S. Fish and Wildlife Service, Southeast Region, 2002, http://www.fws.gov/southeast/news/2003/rcw/partial_map.jpg (accessed March 6, 2006)the species in 2002. In 2003 the U.S. Fish and Wildlife Service published an updated recovery plan for the red-cockaded woodpecker and estimated that approximately 14,000 of the birds were in existence at that time.

In March 2001 the Fish and Wildlife Service rescued several red-cockaded woodpeckers from habitat areas in Daniel Boone National Forest in Kentucky. Fifteen woodpeckers in six family groups were relocated to the Carolina Sandhills National Wildlife Refuge in South Carolina and the Ouachita National Forest in Arkansas. Daniel Boone National Forest had become uninhabitable for the woodpeckers after a 1999 infestation of southern pine beetles. The beetles quickly destroyed 90% of local woodpecker habitat despite efforts by Forest Service officials and volunteers to control the insect's spread. The removal of this red-cockaded woodpecker population from Kentucky means that the species is now absent from the state. The bird is also believed extirpated (wiped out) in Maryland, Missouri, New Jersey, and Tennessee.

In September 2005 the FWS initiated a five-year review of the red-cockaded woodpecker to ensure that the endangered status listing is still appropriate for the species.

IVORY-BILLED WOODPECKERS

The ivory-billed woodpecker (Campephilus principalis) is the largest woodpecker species in the United States, with a wingspan up to thirty inches and bodies nearly twenty inches long. The birds have a striking black and white pattern on their bodies and have ivory-colored beaks. The males have brilliant red crests. In the nineteenth century, the species was found throughout the southeastern United States as well as in Cuba. Intense logging and loss of habitat were believed to have driven the birds extinct sometime in the 1940s. Occasional unconfirmed sightings continued to occur over the following decades. John W. Fitzpatrick and his colleagues reported in "Ivory-Billed Woodpecker (Campephilus Principalis) Persists in Continental North America" (Science, June 3, 2005) that scientists at Cornell University had confirmed sightings and a videotape taken of ivory-billed woodpeckers in the Big Woods region of Arkansas. This area is home to the Cache River National Wildlife Refuge. Conservationists are excited that an apparently lost species has been rediscovered.

Passerines

Just over half of all bird species belong to the order Passeriformes and are called passerines. They are informally known as perching birds or songbirds, although not all passerines are truly songbirds. According to the U.S. Department of Agriculture there are more than sixty families in this order, and they include many well-known species, such as robins, bluebirds, larks, blue jays, mockingbirds, finches, wrens, sparrows, swallows, starlings, cardinals, blackbirds, and crows. More than a third of the U.S. species of endangered and threatened birds are passerine (perching) birds.

SOUTHWESTERN WILLOW FLYCATCHER

The southwestern willow flycatcher (Empidonax traillii extimus) is a subspecies of the willow flycatcher. This small bird has a grayish-green back and wings with a pale yellow belly and white-colored throat. It was first listed as endangered in 1995, when less than 600 individuals were believed to be in existence. The bird is found in portions of Arizona, California, Colorado, New Mexico, Nevada, Texas, and Utah. It migrates to Mexico and Central and South America for the winter. The bird feeds on insects and prefers riparian areas (dense vegetation near rivers or streams) for its habitat. It is endangered primarily due to loss of riparian vegetation. In ranching areas, this vegetation is often stripped by grazing livestock. Another factor in the decline is harm from "brood parasites"—bird species that lay their eggs in the nests of other species. Brown-headed cowbirds are brood parasites that threaten the southwestern willow flycatcher. They lay their eggs in the flycatchers nests, and the unsuspecting flycatchers raise the cowbirds' young as their own.

In 1997 the U.S. Fish and Wildlife Service designated critical habitat for the bird in compliance with a court order resulting from a lawsuit filed against the agency by the Southwest Center for Biological Diversity. The critical habitat covered nearly 600 miles of streams and rivers in California, Arizona, and New Mexico. A recovery plan for the bird was finalized in 2002 that includes six recovery units as shown in Figure 9.3. In 2005 the FWS designated new critical habitat for the southwestern willow flycatcher covering 737 miles of waterways in California, Arizona, Nevada, Utah, and New Mexico. The new designation was made in response to a court order.

THE BLACK-CAPPED VIREO AND GOLDEN-CHEEKED WARBLER

The black-capped vireo and golden-cheeked warbler are among the threatened songbirds listed under the Endangered Species Act. Both species nest in central Texas and other locations in the United States and winter in Mexico and Central America. Both species have declined largely due to loss of habitat caused by land clearing for development and invasion of brown-headed cowbirds. In certain areas, more than half the black-capped vireo nests contain eggs of brood parasites called brown-headed cowbirds. The black-capped vireo was placed on the Endangered Species List in 1987; the golden-cheeked warbler was listed in 1990.

Much of the critical nesting habitat for black-capped vireos and golden-cheeked warblers lies in the Hill Country of central Texas. The Texas Hill Country is characterized by diverse habitats and a high concentration of rare bird species. In the last decade, however, increased water demand by metropolitan areas has caused the local Edwards Aquifer to drop by thirty feet, resulting in a 15% to 45% decrease in available bird habitat. In an effort to balance development with wildlife preservation, the city of Austin, Texas, invited the Nature Conservancy to formulate a plan to protect Hill Country habitats while enabling some development. The result was the Balcones Canyonlands Conservation Plan, which includes a 75,000-acre preserve in the Texas Hill Country.

FIGURE 9.3 Recovery areas for the Southwestern willow flycatcher "Figure 4. Recovery and Management Units for the Southwestern Willow Flycatcher," in Final Recovery Plan, Southwestern Willow Flycatcher (Empidonax traillii extimus), U.S. Department of the Interior, U.S. Fish and Wildlife Service, August 2002, http://ecos.fws.gov/docs/recovery_plans/2002/020830c.pdf (accessed March 6, 2006)

Fort Hood, Texas, a heavy artillery training site for the U.S. Army, was designated essential nesting habitat for the golden-cheeked warbler and black-capped vireo in 1993. With the help of the Nature Conservancy, the Army currently manages some 66,000 acres of habitat for these species. Control of brown-headed cowbird populations has been a major part of the conservation efforts. Brown-headed cowbirds parasitize the nests of over 200 species of songbirds, and have caused declines in many of these species. Nest parasitism rates for the black-capped vireo were as high as 90% before control measures were begun. They have been reduced to less than 10%. Many other bird species also use habitat at Fort Hood, including threatened and endangered species such as the bald eagle, peregrine falcon, and whooping crane.

THE COASTAL CALIFORNIA GNATCATCHER

The coastal California gnatcatcher (Polioptila californica californica) is a small, gray and black songbird known for its kitten-like mewing call. Gnatcatchers are nonmigratory, permanent residents of California coastal sage scrub communities, one of the most threatened vegetation types in the nation. In 1995 the U.S. Geological Survey estimated that more than 85% of coastal sage scrub had been destroyed or significantly degraded in Southern California since the time of European settlement.

The Fish and Wildlife Service estimated in 1993 that approximately 2,500 pairs of California gnatcatchers remained in the United States. The plight of the species has emphasized the importance of preserving coastal sage scrub habitat, which supports many other distinctive species as well. The California gnatcatcher was listed as threatened across its entire range in California and Mexico in 1993. In an effort to protect the birds, in 2003 the FWS proposed a critical habitat area of more than 495,000 acres of land covering portions of Ventura, Los Angeles, Orange, Riverside, San Bernardino and San Diego counties.

Hawaiian Honeycreepers

The Hawaiian honeycreepers are a group of songbirds endemic to Hawaii—that is, species in this group are found there and nowhere else on Earth. Hawaiian honeycreepers are believed to have radiated—formed many separate species, each adapted to a particular life-style—from a single species that colonized the Hawaiian Islands thousands of years ago. The honeycreepers are named for the characteristic "creeping" behavior some species exhibit as they search for nectar. The Hawaiian honeycreepers are extremely diverse in their diet—different species are seed-eaters, insect-eaters, or nectar-eaters. Species also differ in the shapes of the beaks and in plumage coloration. Hawaiian honeycreepers are found in forest habitats at high elevations. According to Abso-luteastronomy.com (http://www.absoluteastronomy.com/reference/hawaiian_honeycreeper) there were some fifty or sixty Hawaiian honeycreeper species originally, but a third of them are already extinct.

Ten species of Hawaiian honeycreepers are currently listed as endangered. Some honeycreeper species are among the most endangered animals on earth, with only a few individuals left. One of the primary factors involved in honeycreeper endangerment is loss of habitat. The Hawaiian Islands are estimated to retain a mere 20% to 30% of their original forest cover. In addition, the introduction of predators that hunt birds or eat their eggs, such as rats, cats, and mongooses, have contributed to the decline of numerous species. The introduction of bird diseases, particularly those spread by introduced mosquitoes, has also decimated honeycreeper populations. The success of mosquitoes in Hawaii has been dependent on another introduced species—pigs. The rooting activity of pigs creates pools of water where mosquitoes lay their eggs. In fact, the greater the number of pigs in a habitat, the more bird disease will be prevalent. Finally, competition with introduced bird species for food and habitat has also been a significant cause of decline.

The Po'ouli is the most endangered Hawaiian honeycreeper and may already be extinct. Along with many other endangered native species, it occupies the Hanawi Natural Reserve Area in Maui, which has been aggressively rehabilitated and cleared of invasive species. The bird was only discovered during the 1970s. At that time less than 200 individuals existed in the wild. By 2004 there were only three Po'ouli birds left. Scientists captured one of the birds, but he died a few months later, apparently of avian malaria. As of March 2006 the remaining two individuals have not been located and may already have died.

In 2003 the U.S. Fish and Wildlife Service published a recovery plan for nineteen endangered Hawaiian forest birds. The agency reports that ten of these species have not been definitely observed in at least a decade and may well be extinct already. Most of these species are native to rain forests at elevations above 4,000 feet on the islands of Hawaii (Big Island), Maui, and Kauai. Major threats to endangered forest species include habitat loss and modification, other human activity, disease, and predation. Of particular importance are nonnative plants, which have converted native plant communities to alien ecosystems unsuitable as habitat.

It is estimated that two-thirds of Hawaii's original bird fauna is already extinct. Of the remaining one-third, a large majority are imperiled. Habitat destruction in Hawaii has been so extensive that all the lowland species now present are nonnative species introduced by humans.

Migratory Songbirds

There are more than 200 species of songbirds known as neotropical migraters. Every year these birds migrate between the United States and tropical areas in Mexico, the Caribbean, and Central and South America. Although some songbirds are appreciated by humans for their beautiful songs and colorful plumage, migratory songbirds also play a vital role in many ecosystems. During spring migration in the Ozarks, for example, dozens of migratory bird species arrive and feed on the insects that inhabit oak trees, thereby helping to control insect populations.

Migratory species are particularly vulnerable because they are dependent on suitable habitat in both their winter and spring ranges. In North America, real estate development has eliminated many forest habitats. Migratory songbird habitats are also jeopardized in Central and South America, where farmers and ranchers have been burning and clearing tropical forests to plant crops and graze livestock. Some countries, including Belize, Costa Rica, Guatemala, and Mexico, have set up preserves for songbirds, but improved forest management is needed to save them.

Raptors (Birds of Prey)

The term raptor is derived from the Latin word raptores, which was once the order on the taxonomy FIGURE 9.4 The bald eagle was once endangered due to habitat destruction and pollution by pesticides, such as DDT. Its populations have recovered with protection and a ban on DDT. (Field Mark Publications.)table to which birds of prey were assigned. Eventually scientists split the birds into three orders as follows:

  • Accipitriformes—includes hawks, eagles, and buzzards
  • Falconiformes—falcons
  • Strigiformes—owls

As shown in Table 9.1 there were less than a dozen raptors listed as endangered or threatened in the United States as of March 2006. Species of note include the bald eagle, northern spotted owl, and California condor.

THE BALD EAGLE

The bald eagle (Haliaeetus leucocephalus) is a raptor with special status in the United States. (See Figure 9.4.) A symbol of honor, courage, nobility, and independence (eagles do not fly in flocks), the bald eagle is found only in North America, and its image is engraved on the official seal of the United States of America. There were an estimated 100,000 bald eagles in the country in the late eighteenth century when the nation was founded.

The bald eagle nests over most of the United States and Canada, building its aerie, or nest, in mature conifer forests or on top of rocks or cliffs. Its nest is of such a grand size—sometimes as large as a small car—that a huge rock or tree is necessary to secure it. The birds use the same nest year after year, adding to it each nesting season. It is believed that eagles mate for life. Bald eagles prey primarily on fish, water birds, and turtles.

Bald eagles came dangerously close to extinction in the twentieth century, largely due to the pesticide DDT, which was introduced in 1947. Like other carnivorous species, bald eagles ingested large amounts of DDT by eating prey that had been exposed to it. DDT either prevents birds from laying eggs or causes the eggshells to be so thin they are unable to protect eggs until they hatch. The Bald Eagle Protection Act of 1940, which made it a federal offense to kill bald eagles, helped protect the species. However, numbers continued to dwindle and the bald eagle was listed as endangered in 1967.

Bald eagle populations started to recover with the banning of DDT in 1972. The species also benefited from habitat protection and attempts to clean up water pollution. In 1995 the bald eagle was moved from endangered to threatened status on the Endangered Species List. In 1999 the species was proposed for delisting. A year later all delisting criteria contained in species recovery plans were achieved. However, the FWS has been slow to carry through with the delisting process. In February 2006 the agency reopened the public comment period on the delisting proposal. Public comments were to be accepted until May 2006. The FWS news release announcing the reopening (February 16 2006, http://www.fws.gov/migratorybirds/issues/BaldEagle/Reopening.Comments.06.pdf) notes that there were an estimated 7,066 nesting pairs of bald eagles in the United States at that time.

NORTHERN SPOTTED OWL

The northern spotted owl (Strix occidentalis caurina) occupies old-growth forests in the Pacific Northwest, where it nests in the cavities of trees 200 years old or older. It does not seem afraid of humans and in fact appears to be curious about humans and human activity. Its primary prey includes the nocturnal northern flying squirrel, mice, and other rodents and reptiles. According to the Sierra Club, owl pairs may forage across areas as large as 2,200 acres.

Northern spotted owl populations have declined primarily due to habitat loss. Most of the private lands in its range have been heavily logged, leaving only public lands, such as national forests and national parks, for habitat. Because logging has also been permitted in many old-growth national forest areas, the species has lost approximately 90% of its original habitat. In 1990 the U.S. Fish and Wildlife Service placed the northern spotted owl on its list of threatened species. Court battles began over continued logging in national forest habitats. In 1991 a U.S. federal district court ruled in favor of the Seattle Audubon Society and against the U.S. Forest Service, declaring that the Forest Service was not meeting its obligation to "maintain viable populations." The Forest Service had argued that the FWS was responsible for the management and recovery of this species. However, the court pointed out that the Forest Service had its own distinct obligations to protect species under the Endangered Species Act, and that courts had already reprimanded the FWS for failing to designate critical habitat for the northern spotted owl.

In 1992 the FWS set aside seven million acres as critical habitat for the species and published a recovery plan. A year later the Northwest Forest Plan was established. It reduced logging in thirteen national forests by about 85% to protect northern spotted owl habitats. However, populations of the northern spotted owl continued to decline—this despite the unanticipated discovery of fifty pairs of nesting adults in California's Marin County, just north of the Golden Gate Bridge.

In 2004 the U.S. Fish and Wildlife Service completed a five-year status review of the northern spotted owl. The review was conducted in response to a lawsuit filed by the Western Council of Industrial Workers. The agency concluded that the bird should continue to have a threatened listing under the Endangered Species Act. The FWS found that habitat loss on federal lands has been minimized since the species was originally listed. This success is attributed to the Northwest Forest Plan. However, the agency found that the population of northern spotted owls in Washington, Oregon, and California has continued to decline, and the species faces emerging threats from forest fires, West Nile virus, sudden oak death (a plant disease that has killed hundreds of thousands of trees in California and Oregon), and competition for habitat from barred owls.

In January 2006 the FWS announced its intention to develop a final recovery plan for the northern spotted owl. A draft recovery plan, issued in 1992, was never finalized by the agency. The new recovery plan is expected to address recovery and conservation on non-federal lands and establish delisting criteria. New final designation of critical habit for the species is expected by the end of 2007.

THE CALIFORNIA CONDOR

The California condor (Gymnogyps californianus) has a wingspan in excess of nine feet, and is among the continent's most impressive birds. Ten thousand years ago, this species soared over most of North America. However, its range contracted at the end of the Ice Age, and eventually individuals were found only along the Pacific Coast. Like other vulture species, the California condor is a carrion eater, and feeds on the carcasses of deer, sheep, and smaller species such as rodents. Random shooting, egg collection, poisoning, and loss of habitat devastated the condor population. The spe-FIGURE 9.5 Captively bred condors Zookeepers use hand puppets that look like adult condors to feed captively bred condor chicks. "Captively-Bred Condors," in California Condor, U.S. Fish and Wildlife Service, August 1998, http://training.fws.gov/library/Pubs/condor.pdf (accessed April 4, 2006)cies was listed as endangered in 1967. Oliver H. Pattee and Robert Mesta in "California Condors" (http://biology. usgs.gov/s+t/noframe/b162.htm#9944) show that by 1984 only eleven condors remained in the wild. After five of these birds died, the FWS decided to capture the remaining population.

An intense captive breeding program for the California condor was initiated in 1987. (See Figure 9.5.) The first chick hatched in 1988. The breeding program was successful enough that California condors were released into the wild beginning in 1992. Four years later a release took place near the Grand Canyon, providing spectacular opportunities to view the largest bird in North America. The introduced birds in parts of Arizona, Nevada, and Utah were designated a nonessential experimental population. The California condor is listed as endangered in the remainder of Arizona and all of California and Oregon.

In April 2002, for the first time in eighteen years, a condor egg laid in the wild hatched in the wild. The parents of this chick had been captive-bred at the Los Angeles Zoo and the San Diego Wild Animal Park respectively and released into the wild in 1995 at the age of one. Between 2001 and 2005 three wild-born condor chicks died, one from West Nile virus and two from eating trash (fragments of plastic, metal, glass, and fabric). During the summer of 2005 biologists removed a sickly chick from its nest and performed surgery to remove trash from the bird's stomach. The surgery was successful and the chick was expected to be released back to the wild in the spring of 2006.

In September 2005 the U.S. Fish and Wildlife Service announced that 125 condors were known to be living in the wild and 151 were in captivity at the Los Angeles Zoo, San Diego Wild Animal Park, the Oregon Zoo, and the Peregrine Fund's World Center for Birds of Prey in Boise, Idaho.

Water Birds

Water birds live in and around bodies of water. Some prefer marine (ocean) habitats and others are found only near freshwater. Many species inhabit swamps and wetlands. These areas may be inland or intertidal (along the sea coast).

There were more than two dozen water birds listed as endangered or threatened in the United States as of March 2006. They include a variety of species from many different taxonomic orders.

MIGRATORY SHORE BIRDS

Migratory shore birds are found most often in marshes, mudflats, estuaries, and other wetland areas where the sea meets freshwater. This category includes plovers, stilts, snipes, oystercatchers, avocets, shearwaters, and sandpipers. These birds vary greatly in size and color, but nearly all migrate over very long distances. Most of them breed near the North Pole in the spring and spend their winters anywhere from the southern United States to South America. During their annual migrations, the birds stop to rest and feed at specific locations, known as staging areas, in the United States. Major staging areas include Delaware Bay, the Copper River Delta in Alaska, Cheyenne Bottoms in Kansas, San Francisco Bay, and the Great Salt Lake in Utah.

SEA BIRDS

Sea birds spend most of their time out at sea, but nest on land. They are also known as pelagic birds, because pelagic means oceanic (associated with the open seas). Sea bird species include gulls, terns, albatrosses, puffins and penguins, kittiwakes, petrels, murres and murrelets, auks and auklets, and cormorants.

The marbled murrelet (Brachyramphus marmoratus) is one of a handful of sea birds listed under the Endangered Species Act. The bird was first listed in 1992 and is designated as threatened in California, Oregon, and Washington. The marbled murrelet is about nine inches long and has a distinctive two-tone pattern of dark and light markings. The species prefers to nest in the trees of old-growth forests along the Pacific Northwest coastline. Logging and other causes of habitat degradation have resulted in population declines.

In 2004 the U.S. Fish and Wildlife Service completed a five-year status review for the marbled murrelet. The agency concluded that the population living in Oregon, Washington, and California did not quality for a listing as a distinct population segment under the Endangered FIGURE 9.6 The wood stork is a wading bird "The Wood Stork Is an Indicator," in Wood Stork: Everglades National Park, U.S. Department of the Interior, National Park Service, Everglades National Park, November 17, 1997, http://www.nps.gov/ever/eco/wdstork.htm (accessed March 6, 2006)Species Act and that the species should retain its listing as threatened. However, the agency has decided to conduct a species-wide review to determine if the listed range of the bird needs to be modified. The status review was performed in response to a lawsuit filed by the American Forest Resources Council and other parties.

WADING BIRDS

Wading birds are unusual birds characterized by long, skinny legs and extended necks and beaks. They wade in the shallow waters of swamps, wetlands, and bays where they feed on aquatic life forms. Wading birds include species of egret, crane, stork, and ibis. As of March 2006 there were two wading birds of note listed under the ESA: the wood stork (Mycteria americana) and the whooping crane (Grus americana).

The wood stork (see Figure 9.6) weighs only about five pounds, but stands up to three feet tall with a five-foot wing span. At one time tens of thousands of the birds inhabited the southeast coastline. In 1984 the species was listed under the ESA as endangered in Alabama, Florida, Georgia, and South Carolina. A recovery plan for the bird was published in 1999. At that time about 5,000 breeding pairs lived in the wild. Populations have declined in the Everglades in southern Florida, but increased in coastal areas farther north. In a 2005 report the FWS estimated the number of adult wood storks to be 16,000 (http://www.fws.gov/northflorida/Species-Accounts/Wood-stork-2005.htm).

Standing five feet tall, the whooping crane (see Figure 9.7) is North America's tallest bird and among the best known endangered species in the United States. Its name comes from its loud and distinctive call, which can be heard for miles. Historically whooping cranes lived FIGURE 9.7 The whooping crane is highly endangered. Each year whooping cranes migrate from breeding grounds in Canada to wintering grounds in south Texas. Field Mork Publicationsacross the Great Plains and southeast coast of the United States. The birds were once heavily hunted, for meat as well as for their beautiful, long white feathers. In addition, the heavy loss of wetland areas in the United States deprived whooping cranes of much of their original habitat. In 1937 it was discovered that fewer than twenty whooping cranes were left in the wild in two small populations—a migratory population that nested in Canada and wintered on the Texas coast and a nonmigratory population living in Louisiana.

Each year, the migratory whooping cranes fly 2,500 miles from nesting grounds in Wood Buffalo, Canada, to Aransas, Texas, for the winter before returning north in March to breed. Whooping cranes return to the same nesting site each year with the same mate. In 1937 the Aransas Wildlife Refuge was established in south Texas to protect the species' wintering habitat. Conservation efforts for the whooping crane are coordinated with the Canadian government, which manages the birds' breeding areas.

The whooping crane is listed under the ESA as endangered in Colorado, Kansas, Montana, North Dakota, Nebraska, Okalahoma, South Dakota, and Texas. Nonessential experimental populations were designated in 1993 and 2001 in dozens of states from Wyoming to Florida. In 2001 the first introduced cranes in Wisconsin were led to their Florida wintering grounds along the migration route by ultralight aircraft. The birds successfully made the return trip on their own in following years.

In September 2005 the U.S. Geological Survey reported 340 whooping cranes living in the wild and 135 individuals in captive populations.

OTHER BIRDS

Other birds listed under the Endangered Species Act include nonmigratory shore birds, such as the clapper rail and the Guam rail (a flightless bird); swimming birds, including coots, ducks, eiders, and geese; ground-dwelling birds, such as the prairie chicken; and coastal dwellers, such as the brown pelican.

Birds - General Threats To U.s. Bird Species [next]

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