Black-necked Stilt
Encyclopedia
The Black-necked Stilt (Himantopus mexicanus) is a locally abundant shorebird of American
wetlands and coastlines. It is found from the coastal areas of California
through much of the interior western United States and along the Gulf of Mexico
as far east as Florida
, then south through Central America
and the Caribbean
to northwest Brazil
southwest Peru
,east Ecuador
and the Galápagos Islands
. The northernmost populations, particularly those from inland, are migratory
, wintering from the extreme south of the United States to southern Mexico
, rarely as far south as Costa Rica
; on the Baja California
peninsula it is only found regularly in winter.
of the Common or Black-winged Stilt
, using the trinomial name Himantopus himantopus mexicanus. However, the AOU
has always considered it a species
in its own right, and the scientific name Himantopus mexicanus is often seen. Matters are more complicated though; sometimes all five distinct lineages of the Common Stilt are treated as different species. But the White-necked Stilt from southern South America
(H. h. melanurus when only one species is recognized), parapatric and intergrading to some extent with its northern relative where their ranges meet, would warrant inclusion with the Black-necked stilt when this is separated specifically, becoming Himantopus mexicanus melanurus. Similarly, the Hawaiian Stilt, H. h. knudseni, is likely to belong to the American species when this is considered separate; while some treat it as another distinct species, the AOU, BirdLife International
and the IUCN do not. Thus, in their scheme the Black-necked Stilt is properly named Himantopus mexicanus mexicanus.
Downy young are light olive brown with lengthwise rows of black speckles (larger on the back) on the upperparts – essentially where adults are black – and dull white elsewhere, with some dark barring on the flanks.
Where their ranges meet in central Brazil
, the Black-necked and White-backed stilts intergrade. Such individuals often have some white or grey on top of the head and a white or grey collar separating the black of the hindneck from that of the upper back.
The Black-necked Stilt is distinguished from non-breeding vagrants of the Old World
Black-winged Stilt by the white spot above the eye. Vagrants of the northern American form in turn is hard to tell apart from the resident Hawaiian Stilt, in which only the eye-spot is markedly smaller. But though many stilt populations are long-distance migrants and during their movements can be found hundreds of miles offshore, actual trans-oceanic vagrants are nonetheless a rare occurrence.
The Black-necked Stilt is found in estuarine, lacustrine
, salt pond and emergent wetland
habitat
s; it is generally a lowland bird but in Central America
has been found up to 8,200 ft (2,500 m) ASL
and commonly seen in llanos
habitat in northern South America
. It is also found in seasonally flooded wetlands. Use of salt evaporation pond
s has increased significantly since 1960 in the USA, and they may now be the primary wintering habitat; these salt ponds are especially prevalent in southern San Francisco Bay
. At the Salton Sea
, the Black-necked Stilt is resident year-round.
This bird is locally abundant in the San Joaquin Valley
, where it commonly winters. It is common to locally abundant in appropriate habitat in southern California
from April to September.
It also breeds along lake shores in northeastern California and southeastern Oregon
as well as along the Colorado River
. In North America outside California, the Black-necked Stilt rarely breeds inland, but it is known as a breeding bird in riparian locales in Arizona
and elsewhere in the southern USA. In Arizona, Black-necked Stilts may be seen along artificially created lakes and drainage basins in the Phoenix
metropolitan area, in remnant riparian habitat.
In the San Francisco Bay Area
, specific locations where one would expect to see this bird are Richardson Bay
(especially, according to mudflat bird sightings, the mouth of Pickleweed Creek), mudflats of Belmont Slough, mudflats of Seal Slough
in San Mateo
, salt ponds in Hayward
, California
, exposed bay mud
s on the Burlingame
estuarine
shore, and Heron's Head Park at India Basin
.
For the populations that summer in the Sierra Nevada of northeast California and southeastern Oregon as well as the plateau lakes of those areas, breeding occurs after those flocks migrate
to lowland and coastal areas each August or September. For flocks that summer in the northern Central Valley of California, a migration occurs to the San Joaquin Valley
to consolidate with flocks that were already summering there. In coastal areas flocks both summer and winter in these estuarine settings.
Fall migration of the northernly birds takes place from July to September, and they return to the breeding grounds between March and May Usually, the entire population breeding at any one site arrives, mates, incubates eggs for about a month, and protects and broods the young until they are capable of sustained flight (at 27–31 days old) and leaves again migrating in flocks of about 15 individuals sometimes juveniles congregating in small groups and other times siblings with family groups . There is some seasonal movement of the tropical populations, but this is not long-range and poorly understood.
The parasitic cyclocoeline
flatworm
Neoallopyge americanensis was described from the air sacs of a Black-necked Stilt from Texas
. Its genus
is presently monotypic
and seems to be closely related to the similar genus Allopyge, found in Old World
crane
s.
The Black-necked Stilt forages by probing and gleaning primarily in mudflats and lakeshores, but also in very shallow waters near shores; it seeks out a range of aquatic invertebrates – mainly crustacean
s and other arthropod
s, and mollusks – and small fish
, tadpole
s and very rarely plant seeds. Its mainstay food varies according to availability; inland birds usually feed mainly on aquatic insect
s and their larva
e, while coastal populations mostly eat other aquatic invertebrates. For feeding areas they prefer coastal estuaries, salt ponds, lakeshores, alkali flats and even flooded fields. For roosting and resting needs, this bird selects alkali flats (even flooded ones), lake shores, and islands surrounded by shallow water.
This stilt chooses mudflats, desiccated lacustrine
verges, and levee
s for nest locations, as long as the soil is friable. Reproduction occurs from late April through August in North America
, with peak activity in June, while tropical populations usually breed after the rainy season. The nests are typically sited within one kilometer of a feeding location, and the pairs defend an extensive perimeter around groups of nests, patrolling in cooperation with their neighbors. Spacing between nests is approximately 65 ft (c.20 m), but sometimes nests are within 7 ft (2 m) of each other and some nests in the rookery
are as far as 130 ft (40 m) from the nearest neighbor. The Black-necked Stilt is actually classified as semicolonial
since the nests are rarely found alone and colonies usually number dozens, rarely hundreds of pairs. The nests are frequently established rather close to the water edge, so that their integrity is affected by rising water levels of ponds or tides. This is particularly a hazard in the case of managed salt ponds where water levels may be altered rapidly in the salt pond flood
ing process.
The clutch
size generally is 3-5 eggs with an average of four. For 22–26 days both sexes take turns incubating
the eggs. The young are so precocial
that they are seen swimming within two hours after hatching and are also capable of rapid land velocity
at that early time. In spite of this early development the young normally return to the nest for resting for one or two more days. They fledge after about one month but remain dependent on their parents for some more weeks. Birds begin to breed at 1–2 years of age.
affecting both the birds directly as well as their food stocks. But altogether, the population is healthy and occurs over a large range. This stilt is therefore classified as a Species of Least Concern
by the IUCN. The Hawaiian Stilt, separated with the Black-necked Stilt in a distinct species by some (including the IUCN), is very rare however and numbers less than 2,000 individuals. Predation
by the Small Indian Mongoose (Herpestes javanicus auropunctatus), introduced to hunt rats, is suspected to have contributed to its decline.
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
wetlands and coastlines. It is found from the coastal areas of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
through much of the interior western United States and along the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
as far east as Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, then south through Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
to northwest Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
southwest Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
,east Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
and the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
. The northernmost populations, particularly those from inland, are migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, wintering from the extreme south of the United States to southern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, rarely as far south as Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
; on the Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
peninsula it is only found regularly in winter.
Taxonomy
It is often treated as a subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Common or Black-winged Stilt
Black-winged Stilt
The Black-winged Stilt or Common Stilt is a widely distributed very long-legged wader in the avocet and stilt family . Opinions differ as to whether the birds treated under the scientific name H. himantopus ought to be treated as a single species and if not, how many species to recognize...
, using the trinomial name Himantopus himantopus mexicanus. However, the AOU
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
has always considered it a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in its own right, and the scientific name Himantopus mexicanus is often seen. Matters are more complicated though; sometimes all five distinct lineages of the Common Stilt are treated as different species. But the White-necked Stilt from southern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
(H. h. melanurus when only one species is recognized), parapatric and intergrading to some extent with its northern relative where their ranges meet, would warrant inclusion with the Black-necked stilt when this is separated specifically, becoming Himantopus mexicanus melanurus. Similarly, the Hawaiian Stilt, H. h. knudseni, is likely to belong to the American species when this is considered separate; while some treat it as another distinct species, the AOU, BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
and the IUCN do not. Thus, in their scheme the Black-necked Stilt is properly named Himantopus mexicanus mexicanus.
Description
Adults have long pink legs and a long thin black bill. They are white below and have black wings and backs. The tail is white with some grey banding. A continuous area of black extends from the back along the hindneck to the head. There, it forms a cap covering the entire head from the top to just below eye-level, with the exception of the areas surrounding the bill and a small white spot above the eye. Males have a greenish gloss to the back and wings, particularly in the breeding season. This is less pronounced or absent in females, which have a brown tinge to these areas instead. Otherwise, the sexes look alike.Downy young are light olive brown with lengthwise rows of black speckles (larger on the back) on the upperparts – essentially where adults are black – and dull white elsewhere, with some dark barring on the flanks.
Where their ranges meet in central Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, the Black-necked and White-backed stilts intergrade. Such individuals often have some white or grey on top of the head and a white or grey collar separating the black of the hindneck from that of the upper back.
The Black-necked Stilt is distinguished from non-breeding vagrants of the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
Black-winged Stilt by the white spot above the eye. Vagrants of the northern American form in turn is hard to tell apart from the resident Hawaiian Stilt, in which only the eye-spot is markedly smaller. But though many stilt populations are long-distance migrants and during their movements can be found hundreds of miles offshore, actual trans-oceanic vagrants are nonetheless a rare occurrence.
Distribution and habitat
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
, salt pond and emergent wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s; it is generally a lowland bird but in Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
has been found up to 8,200 ft (2,500 m) ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...
and commonly seen in llanos
Llanos
The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the Flooded grasslands and savannas Biome....
habitat in northern South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It is also found in seasonally flooded wetlands. Use of salt evaporation pond
Salt evaporation pond
Salt evaporation ponds, also called salterns or salt pans, are shallow artificial ponds designed to produce salts from sea water or other brines. The seawater or brine is fed into large ponds and water is drawn out through natural evaporation which allows the salt to be subsequently harvested...
s has increased significantly since 1960 in the USA, and they may now be the primary wintering habitat; these salt ponds are especially prevalent in southern San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
. At the Salton Sea
Salton Sea
The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death...
, the Black-necked Stilt is resident year-round.
This bird is locally abundant in the San Joaquin Valley
San Joaquin Valley
The San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...
, where it commonly winters. It is common to locally abundant in appropriate habitat in southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
from April to September.
It also breeds along lake shores in northeastern California and southeastern Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
as well as along the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
. In North America outside California, the Black-necked Stilt rarely breeds inland, but it is known as a breeding bird in riparian locales in Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
and elsewhere in the southern USA. In Arizona, Black-necked Stilts may be seen along artificially created lakes and drainage basins in the Phoenix
Phoenix, Arizona
Phoenix is the capital, and largest city, of the U.S. state of Arizona, as well as the sixth most populated city in the United States. Phoenix is home to 1,445,632 people according to the official 2010 U.S. Census Bureau data...
metropolitan area, in remnant riparian habitat.
In the San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
, specific locations where one would expect to see this bird are Richardson Bay
Richardson Bay
Richardson Bay is a shallow, ecologically rich arm of San Francisco Bay, managed under a Joint Powers Agency of four Northern California cities. The Richardson Bay Sanctuary was acquired in the early 1960s by the National Audubon Society. The bay was named for William A...
(especially, according to mudflat bird sightings, the mouth of Pickleweed Creek), mudflats of Belmont Slough, mudflats of Seal Slough
Seal Slough
Seal Slough is a narrow winding tidal channel through a tidal marsh in San Mateo and Foster City, California. This slough has been the object of a wetland restoration project in recent years to enhance habitat value. Dredging has been carried out in Seal Slough since at least 1954...
in San Mateo
San Mateo, California
San Mateo is a city in San Mateo County, California, United States, in the San Francisco Bay Area. With a population of approximately 100,000 , it is one of the larger suburbs on the San Francisco Peninsula, located between Burlingame to the north, Foster City to the east, Belmont to the south,...
, salt ponds in Hayward
Hayward, California
Hayward is a city located in the East Bay in Alameda County, California. With a population of 144,186, Hayward is the sixth largest city in the San Francisco Bay Area and the third largest in Alameda County. Hayward was ranked as the 37th most populous municipality in California. It is included in...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, exposed bay mud
Bay mud
Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles...
s on the Burlingame
Burlingame, California
Burlingame is a city in San Mateo County, California. It is located on the San Francisco Peninsula and has a significant shoreline on San Francisco Bay. The city is named after diplomat Anson Burlingame. It is renowned for its many surviving examples of Victorian architecture, its affluence, and...
estuarine
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
shore, and Heron's Head Park at India Basin
India Basin
India Basin is the easternmost neighborhood of San Francisco, California.The parameters of India Basin are roughly the neighborhood surrounding Cargo Way, Third Street, Evans and Innes Avenues to the Hunters Point Naval Shipyard, from the top of the hill to the water.The history of India Basin is a...
.
For the populations that summer in the Sierra Nevada of northeast California and southeastern Oregon as well as the plateau lakes of those areas, breeding occurs after those flocks migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
to lowland and coastal areas each August or September. For flocks that summer in the northern Central Valley of California, a migration occurs to the San Joaquin Valley
San Joaquin Valley
The San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...
to consolidate with flocks that were already summering there. In coastal areas flocks both summer and winter in these estuarine settings.
Fall migration of the northernly birds takes place from July to September, and they return to the breeding grounds between March and May Usually, the entire population breeding at any one site arrives, mates, incubates eggs for about a month, and protects and broods the young until they are capable of sustained flight (at 27–31 days old) and leaves again migrating in flocks of about 15 individuals sometimes juveniles congregating in small groups and other times siblings with family groups . There is some seasonal movement of the tropical populations, but this is not long-range and poorly understood.
The parasitic cyclocoeline
Cyclocoelinae
The Cyclocoelinae are a subfamily of parasitic flatworms of the order Echinostomida. Their definite hosts are waterfowl and other birds such as waders, where the worms are mainly found in the airways.-Genera:* Allopyge Johnston, 1913...
flatworm
Flatworm
The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals...
Neoallopyge americanensis was described from the air sacs of a Black-necked Stilt from Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. Its genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
is presently monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
and seems to be closely related to the similar genus Allopyge, found in Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
crane
Crane (bird)
Cranes are a family, Gruidae, of large, long-legged and long-necked birds in the order Gruiformes. There are fifteen species of crane in four genera. Unlike the similar-looking but unrelated herons, cranes fly with necks outstretched, not pulled back...
s.
Food and feeding
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, and mollusks – and small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
s and very rarely plant seeds. Its mainstay food varies according to availability; inland birds usually feed mainly on aquatic insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and their larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, while coastal populations mostly eat other aquatic invertebrates. For feeding areas they prefer coastal estuaries, salt ponds, lakeshores, alkali flats and even flooded fields. For roosting and resting needs, this bird selects alkali flats (even flooded ones), lake shores, and islands surrounded by shallow water.
Breeding
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
verges, and levee
Levee
A levee, levée, dike , embankment, floodbank or stopbank is an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water levels...
s for nest locations, as long as the soil is friable. Reproduction occurs from late April through August in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, with peak activity in June, while tropical populations usually breed after the rainy season. The nests are typically sited within one kilometer of a feeding location, and the pairs defend an extensive perimeter around groups of nests, patrolling in cooperation with their neighbors. Spacing between nests is approximately 65 ft (c.20 m), but sometimes nests are within 7 ft (2 m) of each other and some nests in the rookery
Rookery
A rookery is a colony of breeding animals, generally birds. A rook is a Northern European and Central Asian member of the crow family, which nest in prominent colonies at the tops of trees. The term is applied to the nesting place of birds, such as crows and rooks, the source of the term...
are as far as 130 ft (40 m) from the nearest neighbor. The Black-necked Stilt is actually classified as semicolonial
Colonisation
Colonization occurs whenever any one or more species populate an area. The term, which is derived from the Latin colere, "to inhabit, cultivate, frequent, practice, tend, guard, respect", originally related to humans. However, 19th century biogeographers dominated the term to describe the...
since the nests are rarely found alone and colonies usually number dozens, rarely hundreds of pairs. The nests are frequently established rather close to the water edge, so that their integrity is affected by rising water levels of ponds or tides. This is particularly a hazard in the case of managed salt ponds where water levels may be altered rapidly in the salt pond flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing process.
The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
size generally is 3-5 eggs with an average of four. For 22–26 days both sexes take turns incubating
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
the eggs. The young are so precocial
Precocial
In biology, the term precocial refers to species in which the young are relatively mature and mobile from the moment of birth or hatching. The opposite developmental strategy is called "altricial," where the young are born or hatched helpless. Extremely precocial species may be called...
that they are seen swimming within two hours after hatching and are also capable of rapid land velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
at that early time. In spite of this early development the young normally return to the nest for resting for one or two more days. They fledge after about one month but remain dependent on their parents for some more weeks. Birds begin to breed at 1–2 years of age.
Status
Particularly the North American populations of the Black-necked Stilt have somewhat declined in the 20th century, mainly due to conversion of habitat for human use and pollutionPollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
affecting both the birds directly as well as their food stocks. But altogether, the population is healthy and occurs over a large range. This stilt is therefore classified as a Species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the IUCN. The Hawaiian Stilt, separated with the Black-necked Stilt in a distinct species by some (including the IUCN), is very rare however and numbers less than 2,000 individuals. Predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
by the Small Indian Mongoose (Herpestes javanicus auropunctatus), introduced to hunt rats, is suspected to have contributed to its decline.
Further reading
- Hayman, Peter; Marchant, John & Prater, Tony (1986): Shorebirds: an identification guide to the waders of the world. Houghton Mifflin, Boston. ISBN 0-395-60237-8
- Stiles, F. Gary & Skutch, Alexander Frank (1989): A guide to the birds of Costa Rica. Comistock, Ithaca. ISBN 0-8014-9600-4
External links
- Black-necked Stilt Himantopus mexicanus - USGS Patuxent Bird Identification InfoCenter
- Black-necked Stilt Species Account - Cornell Lab of Ornithology
- Black-necked Stilt Information and Photos - South Dakota Birds and Birding
- Black -necked Stilt in Cuba and American Avocet Black-necked Stilt, Zapata Swamp Cuba.