Crab Buzzard

from Wikipedia, the free encyclopedia
Crab Buzzard
Adult shrimp buzzard

Adult shrimp buzzard

Systematics
Class : Birds (aves)
Order : Birds of prey (Accipitriformes)
Family : Hawk species (Accipitridae)
Subfamily : Buzzard-like (buteoninae)
Genre : Black Buzzards ( Buteogallus )
Type : Crab Buzzard
Scientific name
Buteogallus anthracinus
( Deppe , 1830)

The shrimp buzzard ( Buteogallus anthracinus ) is a medium-sized to large, stocky bird of prey from the genus Buteogallus within the subfamily of the buzzard-like (Buteoninae). The almost entirely black or black-brown species with broad, rounded wings and a short banded tail, occurs in the southern USA , the coastal areas of Mexico and Central America , as well as in northern and northeastern South America . The sexes are largely the same in color; Females are only slightly larger, but much heavier than males. Young birds differ significantly from adult shrimp buzzards with their brown top and their belly, which is clearly speckled brown on a light background .

The shrimp buzzards that breed in the northern part of the range (USA and northern Mexico) are largely migratory birds , the birds of the other regions resident birds . The species occurs only near water, preferably in moist habitats such as mangroves , marshes , mud flats , marshy river banks and the like, where it feeds as a food generalist primarily on those animals that can be captured with the least amount of effort. Fish, reptiles and crabs always play a special role.

According to the IUCN , Buteogallus anthracinus , of which five subspecies were recognized as of the end of 2019 , is not endangered (LC = least concern). The generic name ( Buteogallus = chicken buzzard ) refers to the long legs, the specific epithet anthracinus (Greek ανθρακινός = charcoal) to the plumage of the species.

Appearance

The crab buzzard is a mighty, solidly built, almost uniformly black or black-brown buzzard with long legs and short, wide wings , especially in the area of ​​the arm wings. The short, mostly widely diversified tail has a distinctive, wide, white central band. It flies with slow, powerful, deeply drawn wing beats and sails with wings held almost horizontally. There is no color dimorphism , the reverse size dimorphism is marginal and cannot be used for sex determination. The weight dimorphism is much clearer. Young birds are clearly colored differently with a brown upper side and a speckled underside. Males weigh an average of 790 grams, females 1200 grams. The size is in the range of 50 - 56 centimeters.

The shrimp buzzard can easily be confused with the black buzzard , which it resembles to a large extent except for its habit and color of the tail, and in the south of the distribution area with the very similarly colored but somewhat larger black buzzard.

Crab Buzzard. In the middle juvenile
Adult crab buzzards in flight (above young bird)

Adult plumage

The entire top and bottom of the seated bird is black with light brown tones, which intensify as the plumage becomes more worn. The head is also black; lighter, often fawn, is a region behind the base of the beak; There is often a whitish spot above the base of the beak. The white bases of the ruffled neck feathers are recognizable. Up close, the slightly lighter edge of the contour feathers and an indistinct banding on the top of the wing and the feathered leg can be seen; this creates a marbled or wavy impression, especially in the fresh plumage. The tail clearly towers above the wing tips. In the flying bird, the bulging of the wings in the area of ​​the arm swing is noticeable. The underside of the wing is banded slightly reddish-brown and indistinctly black-gray. The hand wings are clearly darker in the terminal half than in the basal half, the arm wings are clearly bordered dark. The two outermost hand wings are partially white in the basal half, creating an elongated white region on the underside of the wings. The black, white-rimmed tail has a distinctive white band almost in its middle on the top and bottom. The legs are orange-yellow. The mighty hooked beak is dark horn-colored at the tip and covered with a yolk-yellow wax skin towards the base . The iris is dark brown.

Youth plumage

Young birds have a longer tail and significantly narrower, less curved wings. The upper side plumage is dark brown; many feathers are edged in light brown or matt white, which creates a speckled impression. The head plumage is lighter and straggly interspersed with dark brown. There is clearly a light brown stripe above the eyes . The underside plumage is irregularly dripped dark brown on a cream-colored ground, as are the under wing-coverts, which, however, are intensely black dashed and spotted. The brownish wings are closely lined with black. Compared to adults, the slightly longer and narrower tail has some dark brown bands of different widths and ends with a wide, dark band. The beak is a little lighter than the colored one, the wax skin tends to be greenish-yellow. The legs are also colored. The iris is dark brown.

In Panamá in particular, pale brown young birds with white plumage are observed with a certain regularity. They are likely to be schizochromic birds that barely reach adulthood.

Mauser

The moulting sequence is not entirely clear and will likely vary depending on the breeding area. The following information applies to North American birds.

Chicks begin to change feathers into their first juvenile plumage at 15 days, which is completed when they leave the nest. Not all large nibs are fully developed at this point. From the first departure the young birds return with different characteristics (mostly some black tail feathers and some fully colored wings) of the first adult plumage; apparently a partial change of the large plumage has taken place in the winter quarters. In the further course of spring they molt the entire plumage and then wear the first adult dress. This is relatively close to the final adult plumage, only the ventral side is still spotted and the wings have the two-zonal appearance of the juvenile plumage on the underside, but are darker than this. It is not clear whether they change to the definitive adult plumage in the following year, or whether a complete moult takes place with a further approach to the adult plumage. After that there is a complete change of feathers every year (females during the breeding season, males afterwards. Migrating buzzards interrupt the moulting started in the breeding area and complete it in the wintering area).

voice

Shrimp buzzards can be heard all year round; in the pre-breeding season they are particularly noticeable acoustically. The main call, which is varied and adapted according to the situation, is a series of shrill, often overturning, short and high call sequences with polyphonic, squeaky and sometimes nasal sound characteristics; the calls are more reminiscent of woodpecker or falcon calls than those of a buzzard. Initially, the pitch increases and the interval between the individual elements is shortened; usually from the middle of the call sequence the pitch drops again and the call fades out. Call sequences comprising only a few elements in a quieter, less shrill tone serve as a communication call.

distribution

Breeding area

Distribution of the shrimp buzzard

The crab Buzzard comes from the southern United States (central and southern Arizona , southwestern New Mexico and southern Texas ; occasionally southern Utah ) southward through Mexico, where he worked in a different width strip the Pacific coastal areas and those at the Gulf Coast settled until Central America before , where it is also breeding bird on both coasts, but largely absent in the interior, as in Mexico. Brood occurrences exist in the coastal regions of the Yucatán and on some offshore islands ( Isla de Cozumel , Islas de la Bahía , or Isla del Rey and other islands off the Panamanian coast). In South America is a coastal strip on the Caribbean coast in northern Colombia , Venezuela and western Guiana breeding area. The species also breeds on Trinidad and St. Vincent . Other occurrences exist on the Colombian Pacific coast and somewhat isolated in the Guayas province in Ecuador . (Especially in the coastal regions of the Gulf of Guayaquil and the offshore islands) Breeding season observations are also available from northernmost Peru . In Colombia, the breeding population extends along the Río Magdalena (and probably also along the Río Meta ) far inland.

habitat

Habitat of the species on the Río Yaqui

The breeding habitats of this species are always on or near water, be it on the seashore or in the bank regions of watercourses. Continuously water-bearing channels are essential, but at least larger stagnant water areas or swamp sections must remain during the dry periods. As far as the breeding areas are not on the coast, where the mangrove is the preferred habitat, the species breeds in woods and gallery forests of different tree compositions that accompany rivers. Denser stocks with high, old trees ( poplars , willows , sycamores , pines , Mexico and Central America often dulce Pithecellobium and in higher areas oaks and Arctostaphylos sp.) Are rarely standing trees clearly preferred. On the coast it inhabits the seaside areas of mangrove, as well as the edges of coastal lagoons, edge zones of alluvial plains , marshes, flooded forest areas and tree-covered, permanently moist grassland with standing puddles and ponds. The shrimp buzzard avoids cultivated, populated land, but tolerates extensive animal husbandry. In montane areas it only breeds in gallery forests along continuously water-bearing rivers.

If shrimp buzzards are not found on the coast, they can colonize high-lying areas along watercourses of up to 2000 meters above sea ​​level (Arizona, Mexico), but the main distribution is in regions below 500 meters.

The districts extend linearly along rivers or seashores and, depending on the topography of the area, reach different distances into the hinterland. The linear extent of the hunting area along a river or the coast varies between 0.67 and 2.7 kilometers. The highest brood density recorded in Mexico was 0.34 pairs / kilometer. 8 breeding pairs were found on an 80 km stretch of a tributary of the Río Yaqui. The breeding site loyalty is very high. Many shrimp buzzards are likely to stay in breeding territory their entire life.

hikes

Only the northernmost breeding populations leave their breeding areas, the birds of all other breeding populations largely remain in the breeding area throughout the year. The departure takes place immediately after the young birds become independent in August and September, and they return in March and April. It is questionable whether regions in central Mexico where a young-ringed shrimp buzzard was found in Arizona can be considered winter quarters.

Food and subsistence

Crabs (here a fiddler crab) are an essential source of food in the maritime habitats
Different water birds belong to the regular prey animals

The shrimp buzzard is not, as its name suggests, specialized in crabs, but, as a food generalist, uses a variety of prey. Depending on the geographical location of the breeding area and the season, different species come to the fore. Individual quantitative analyzes are always just snapshots.

An extensive study carried out in 2008 and 2009 along three tributaries of the Verde River found crabs , fish ( sunfish ), snakes ( Thamnophis sp.), Lizards ( spiny guanes ), frogs ( Rana catesbeiana ), small mammals , birds , their eggs and nestlings, insects and arthropods were found among the prey. Crabs made up over half of the prey animals brought to the nest in 4 of the 16 pairs of buzzards observed. In a comparative study from Durango , 86% of the biomass was accounted for by one species of fish from the sucking carp family , with spiny guans making up the rest, in addition to various large insects.

In the mangrove areas of Central and South America, crabs ( fiddler crabs and other species from the family Ocypodidae , as well as land crabs ) are gaining in importance; Relatively large birds such as various species of heron , ibises (often scarlet ibis ) and rose spoonbills , but also large frogs ( Ceratophrys sp.), of which mostly only the hind legs are consumed, are essential with regard to biomass . Fish are a regular source of food in these habitats (mangrove, shallow water lagoons, marshes), be they stranded specimens or specimens caught in tidal pools. Among the mammals, bats were regularly found in the food analyzes. Shrimp buzzards were often seen on caiman prey remains and along roads where they used animals that had been run over. Occasionally, the consumption of fruits was also noted.

The shrimp buzzard uses different hunting techniques. He often observes the surroundings from a raised hide; if he sees a worthwhile animal, he usually glides without flapping its wings from the control room and hits it on the ground. Before doing this, he often circles at a great height to get an overview. The seats are changed in quick succession, with these changes simultaneously being slow, low search flights, or transitioning into such. Especially in the interior of damp or flooded forests, it flies from tree to tree, only briefly observes a sector, only to fly on again soon. Very often he hunts on the ground, wades on the edge of the bank, or looks for prey in tide pools. Crab buzzards fly fire edges from bush fires to prey on insects or fleeing reptiles and drive breeding birds from their nests to get to their eggs. He tries to surprise small birds in flight from cover, and when he flies past he grabs fish swimming or drifting with both legs like a sea ​​eagle out of the water.

When there is an excess of food, shrimp buzzards set up storage depots in dry places that are hidden from predators.

Breeding biology

It is not known exactly whether shrimp buzzards first breed when they are two or three years old. Probably there is only one annual brood, but replacement clutches, no earlier than one month after the clutch has been lost, are common.

Laying begins in Arizona at the beginning / middle of April, and eggs are laid a little earlier in Mexico. Fresh clutches were found in Colombia in January, in Panama between January and May and in Trinidad between March and July. In the other areas, the species probably breeds in the respective dry seasons.

The breeding site loyalty is very high. Many shrimp buzzards are likely to stay in breeding territory their entire life. Old nests are reused very often (one nest has been used annually for 11 years), but the nests of other birds of prey such as round-tailed corsair or black buzzard are occasionally adapted accordingly.

Pair formation, nest location and nest

The courtship consists mainly of typical buzzard, sometimes impressive courtship flights. The partners fly with accentuated wing beats, soar high and tumble down to the canopy of leaves, occasionally grasping each other with their claws; these sightseeing flights are accompanied by frequent calls. Handing over of food by the male often initiates copulation. As the nest building begins, expressive flights and call activity decrease.

The nest is built at very different heights (2.5 - 42 (!) Meters) in different tree species (mangroves, plane trees, willows, ash , pines, occasionally also in opuntia and others) mostly in a fork in the main trunk. Rock nests were found rather rarely. As the first building, the nest is usually a surprisingly small, spherical structure made of leafy twigs, which the male breaks off (especially from the nest tree) and the female processes it. The inside is covered with fresh leaves, which are regularly replaced until the young ones fly out. However, since nests are often reused several times and regularly renewed and supplemented, they grow over time to form structures over a meter in diameter.

Clutch and young rearing

The clutch consists of 1 - 3 short oval eggs with an average size of 57.3 × 44.9 millimeters. The matt white, often greenish-tinged eggs are irregularly spotted red and dark brown and purple, especially at the long end. The clutch size decreases significantly towards the south. The breeding season is about 37 days; the female always breeds during the night, during the day it is replaced by the male to varying degrees.

The chicks hatch every two days. When hatched, they are covered with fluffy matt white downs; they are unable to sit and can barely lift their heads, but can take small bites of food after an hour. When they are three days old, they sit in the nest, clumsily flapping their wings. The older chick begins to behave aggressively towards its younger sibling at around 8 days, which often leads to its death; However, if both nestlings show a comparable level of aggression, this aggression phase subsides quickly. At this time the chicks can stand and change their position in the nest and the first large feathers break through. When the young are able to cut up prey by themselves or to swallow it whole, the female also begins to hunt again. At 36 days they appear largely feathered; Dune residues can still be seen on the crown of the head and in the cheek region. Often they leave the nest for a while and climb into the nearby branches. At the earliest with 43 days (average 46.8 days), but mostly a little later, they are restricted in flight and finally leave the nest. They then remain in the nesting tree for days, develop their flight skills, but are still completely dependent on the adult birds. This leadership period, in which parental care decreases as the independence of the young birds increases, lasts at least two months. Ferguson-Lees, et al. even report tour times of around 7 months without specifying their origin.

No data are available on the dismigration of young birds.

Breeding success and life expectancy

Only two studies from Arizona are available on breeding success. Of 22 nests that were observed during 2 breeding seasons in a study, 84% made at least one young bird fly. In the more extensive second study, 168 nests were observed, 78% of which caused young birds to fly out. The number of reproductions (= number of young birds flown out per brood started) was 1.31 in one year and 0.98 in the second.

Crab buzzards can reach a very old age in the wild. A young bird ringed in the nest was found again after 13 years and 6 months.

Systematics

B. a. subtilis (adult)
Adult B. a. bangsi with fish booty

In 1830, Pierre Guillaume (Wilhelm) Deppe made an inventory and price list, mainly of bird hides that his brother Ferdinand had brought back from an extended trip to Mexico, and added descriptions of species which he assumed had not yet been described, including the representational species, which he called Falco anthracinus . The type specimen comes from the province of Veracruz in Mexico. It is unclear why the publication was not published under his name, but under the name of Martin Hinrich Lichtensteins. That is why Lichtenstein and not Deppe appeared in the scientific literature as the first to describe it. Erwin Stresemann first noticed this error in 1954 , after which the authorship of this and a number of other species changed from Lichtenstein to Deppe.

Among the black Bussarden is Buteogallus anthracinus with the Hermit Adler , the Rotbauchbussard and Cuba Bussard closely related. The long considered conspecific respected Cuba Buzzard is regarded as a separate species since of 2007. The reasons for this were differences in size, plumage, and voice.

At the end of 2019, 5 subspecies were recognized that are only slightly differentiated in terms of size and plumage color. Two groups can be distinguished: the Atlantic anthracinus and the Pacific subtilis group.

  • Buteogallus anthracinus anthracinus ( Deppe , 1830): USA, Central Mexico and Atlantic coastal areas; Northern Colombia eastwards to Guiana.
  • Buteogallus anthracinus utilensis Twomey , 1956: Island race. Some small islands in the Gulf of Honduras, as well as islands off Cancun and Cozumel. Slightly smaller than the nominate shape, the light spot in the area of ​​the hand wings is missing in these birds.
  • Buteogallus anthracinus subtilis ( Thayer & Bangs , 1905): Pacific coast of Colombia, (uncertain) northwest Ecuador, southwest Ecuador and (uncertain) northernmost Peru. The smallest breed on average. More gray-brown than gray-black. The light spot at the base of the first two arm wings is more obvious than in the nominate form, the undersides of the arm wings show a clear reddish-brown tone. B. a. subtilis is understood by various authorities (Ferguson-Lees and others) together with the two following subspecies as an independent species; As of the end of 2019, however, the majority view has prevailed to regard them as a subspecies.
  • Buteogallus anthracinus rhizophorae Monroe , 1963: Pacific coast from Chiapas south to Nicaragua . Slightly larger than B. a. subtilis , but smaller than B. a. anthracinus . Overall more gray-black than black; the wings are dark gray on the underside, not reddish brown.
  • Buteogallus anthracinus bangsi ( Swann , 1922): Pacific coast of Costa Rica and Panama, pearl islands . In the size between B. a. subtilis and B. a. rhizophorae . Light brown tint of the breast and abdominal plumage, very clear rust-red tint of the arm wings.

Persistence and Threat

All information on the total population of the species is based on projections and estimates based on regional and local population surveys. BirdLife specifies the size of the breeding area to be over 10 million km² and estimates the population of the species to be 2 million individuals with a negative population trend. Ferguson-Lees assumes less than a tenth.

The exposed Viril crayfish is to be eliminated from the waters of the southern United States

In the breeding areas to the north (USA, northern and central Mexico) B. anthracinus is common, but nowhere common. The total population in the USA is estimated at 220–250 breeding pairs. The occurrences on the Yucatán, in Central America and on the Caribbean Atlantic coast, where shrimp buzzards are common in places, are becoming denser. The species is also common on the lower Magdalena River. On the Pacific coast of Colombia, B. anthracinus occurs in all suitable habitats, but the breeding density is not high. No quantitative information is available from the coastal areas of Ecuador, but the population trend seems to be strongly negative.

The main cause of danger is the destruction of the habitat. Large areas of mangroves in particular are cut down for charcoal production or converted into tanks for shrimp farming. Often all types of waste are dumped in such biotopes. Settlements and hotel complexes spread into mangrove areas. In the inland areas of distribution, dam construction projects, increasing deforestation of the river fringes and increasing, non-adapted leisure activities lead to the loss of many breeding sites. Many breeding sites are close to banana plantations, the sewage of which is highly contaminated with biocides and ends up in the shrimp buzzard's hunting grounds. Ingesting contaminated prey animals leads to illness and death, or at least to a lack of fitness. In the US breeding areas, which have been stable in terms of population dynamics, campaigns to eliminate invasive neozoa (crabs, fish) could have negative effects on the breeding population in the short and medium term. In particular, the Viril crayfish , which was released in the Colorado river system in the 1970s, multiplied explosively there and in rivers of northern Mexico. In the northernmost area of ​​distribution it is a not insignificant prey of the shrimp buzzard.

literature

  • RO Bierregaard Jr., DA Christie, P. Boesman, GM Kirwan and JS Marks: Common Black Hawk (Buteogallus anthracinus) . In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, and E. de Juana (eds.). Handbook of the Birds of the World Alive . Lynx Edicions, Barcelona 2019 (downloaded from https://www.hbw.com/node/53111 on December 16, 2019)
  • James Ferguson-Lees , David A. Christie : Raptors of the World . Houghton Mifflin, Boston 2001, ISBN 0-618-12762-3 , pp. 990; Pp. 631-632 .
  • JH Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122

Individual evidence

  1. ↑ a b c d e f g h i j k l James Ferguson-Lees , David A. Christie : Raptors of the World . Houghton Mifflin, Boston 2001, ISBN 0-618-12762-3 , pp. 990; Pp. 631-632 .
  2. ↑ a b c d e JH Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122 Introduction and Appearance
  3. ↑ a b c d e J. H. Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122 Diet
  4. ↑ BirdLife International Species factsheet: Buteogallus anthracinus. Downloaded from http://www.birdlife.org on December 16, 2019
  5. ↑ a b c d e f g R. O. Bierregaard Jr., DA Christie, P. Boesman, GM Kirwan and JS Marks: Common Black Hawk (Buteogallus anthracinus) . In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, and E. de Juana (eds.). Handbook of the Birds of the World Alive . Lynx Edicions, Barcelona 2019 (downloaded from https://www.hbw.com/node/53111 on December 16, 2019)
  6. ↑ James A. Jobling: The Helm Dictionary of scientific Bird Names . Christopher Helm, London 2010. ISBN 978-1-4081-2501-4
  7. ↑ Note: Schizochromism is a genetic defect that causes melanin to be completely absent; the black parts of the plumage therefore appear cream-colored or matt white
  8. ↑ xeno-canto: call sequence
  9. ↑ xeno-canto: communication call
  10. ↑ a b c Juan José Alava, Miguel Saavedra, Xavier Arosemena, Madeleine Calle, Carlos Vinueza, Pedro J. Jiménez, Raúl Carvajal and F. Hernán Vargas: Distributional records and potential threats to the Common (Mangrove) Black Hawk (Buteogallus anthracinus subtilis ) in southwestern Ecuador . In: Boletín SAO, year 20, episode 2, 2011 pdf engl.
  11. ↑ a b J. H. Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122 Distribution
  12. ↑ a b c d e f JH Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122 Demography
  13. ↑ a b c K. E. Etzel, TC Theimer, MJ Johnson, JA Holmes: Variation in Prey delivered to Common Black-Hawk (Buteogallus anthracinus) nests in Arizona Drainage Basins. In: Journal of Raptor Research, Volume 48, Volume 1 2014. pp. 54 - 60 pdf engl.
  14. ↑ F. Hiraldo, M. Delibes, J. Bustamante and R. Estrella: Overlap in the Diets of diurnial Raptors breeding at the Michilía Biosphere Reserve, Durango, Mexico. In: The Journal of Raptor Research Vol. 25, Volume 2; 1994. Pages 25-29. Pdf engl.
  15. ↑ a b c d e f J. H. Schnell: Common Black Hawk (Buteogallus anthracinus) . In: The Birds of North America (AF Poole and FB Gill, eds.). Cornell Lab of Ornithology, Ithaca, NY, USA, 2000; Version 2.0. https://doi.org/10.2173/bna.122 Breeding
  16. ↑ Dr. Jean Cabanis (Ed.): Journal for Ornithology . tape 1-2 , no. 1-12 . Theodor Fischer, Cassel 1853, p. 58 ( biodiversitylibrary.org ).
  17. ^ Erwin Stresemann: Ferdinand Deppe's Travels in Mexico (1824 - 1829). In: The Condor, Jhrg. 56, 1954 pdf engl.
  18. ↑ F. Raposo do Amaral, FH Sheldon, A. Gamauf † , E. Haring, M. Riesing, LF Silveira, and A. Wajntal: Patterns and processes of diversification in a widespread and ecologically diverse avian group, the buteonine hawks (Aves , Accipitridae) In: Molecular Phylogenetics and Evolution Vol. 53; 2009; Pp. 703-715
  19. ^ Forty-eight Supplement to the American Ornithologists' Union Check-List of North American Birds. In The Auk, Jhrg. 124, Episode 3, 2007. S. 1112 pdf engl.
  20. ^ Arthur C. Twomey: A new Race of Black Hawk of the Species Buteogallus anthracinus from the Republic of Honduras . In: Annals of the Carnegie Museum. Year 33.1956. Pp. 387-389. BHL
  21. ^ A b William S. Clark: Taxonomic status and distribution of Mangrove Black Hawk Buteogallus (anthracinus) subtilis. In: Bulletin of the British Ornithologists' Club, Jhrg. 127, 2007 pp. 110-117. BHL
  22. ^ Burt Leavelle Monroe, Jr: A Distributional Survey of the Birds of Honduras. In: LSU Historical Dissertations and Theses. 1046, 1965. pp . 183-189. Diss. Engl.
  23. ↑ BirdLife International (2019) Species factsheet: Buteogallus anthracinus. Downloaded from http://www.birdlife.org on December 21, 2019.
  24. ↑ United States Department of Agriculture / Invasive Aquatic Neozoa - Northern Crayfish