The Chilean hawk (''Accipiter chilensis'') is a
bird of prey
Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predator ...
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
belonging to the
typical hawks. It breeds in
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
forests from central
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
and western
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
south to
Tierra del Fuego
Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...
, from sea level to 2,700 m altitude (though birds are rarely observed above 1,000 m). Some
winter
Winter is the coldest season of the year in Polar regions of Earth, polar and temperate climates. It occurs after autumn and before spring (season), spring. The tilt of Axial tilt#Earth, Earth's axis causes seasons; winter occurs when a Hemi ...
apparently in the lowlands of NW Argentina.
It is sometimes considered to be a subspecies of its northern relative the
bicolored hawk
The bicolored hawk (''Accipiter bicolor'') is a species of bird of prey in the family Accipitridae. It is found in forest, woodland, second growth, plantations, and wooded savanna in southeastern Mexico, Central America, and northern and central ...
(''A. bicolor''), including by the
American Ornithological Society
The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...
and sometimes a distinct species. The two show differences in
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
preference and have
allopatric
Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
distributions. But the situation is complicated by the subspecies ''pileatus'', which is intermediate in plumage between ''bicolor'' and ''chilensis'', and has been variously assigned to either species by those that consider them distinct.
Description
The male is 37 to 38 cm long, while the larger female measures 41 to 42 cm. The adults have black upperparts, and an ash-grey chest and abdomen with dark barring. The throat has longitudinal dark stripes and the undertail is white. The uppertail is brown with 5 or 6 dark bands. The legs are greenish yellow, and the eyes are yellow. The sexes have similar plumage.
Young birds have browner upperparts with cream fringes to the feathers. The paler chest and abdomen have longitudinal stripes. The paler uppertail makes the banding more obvious.
Birds are only vocal during the breeding season. While engaging in reproductive activity, its calls do not seem to differ from those of the bicoloured hawk. This has at least two rather high-pitched scolding vocalizations: a barking row of ''keh'' or ''kow'', and a
woodpecker
Woodpeckers are part of the bird family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar region ...
-like faster and accelerating
staccato
Staccato (; Italian for "detached") is a form of musical articulation. In modern notation, it signifies a note of shortened duration, separated from the note that may follow by silence. It has been described by theorists and has appeared in music ...
of ''kek'' calls. These are given near the nest and might announce intruders such as the scientists coming to study the birds. A series of higher-pitched ''kie'', given by a definite Chilean hawk under similar circumstances, might replace one of the above, or it might be a distinct type of call. Pairmates address each other with a squealing ''waaah'', and a soft clear whistle is apparently used by parents to communicate something to the young.
[Trejo ''et al.'' (2006)]
Distribution
In
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
, it is found north to
Neuquén Province at about 36°
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north po ...
. The northern limit of the breeding range in
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
is not well known. In significant numbers, the Chilean hawk probably only occurs north to
O'Higgins Region
The Libertador General Bernardo O'Higgins Region ( es, Región del Libertador General Bernardo O'Higgins, ), often shortened to O'Higgins Region ( es, Región de O'Higgins), is one of Chile's 16 first order administrative divisions. It is subdi ...
, though it at least occasionally breeds in
ValparaÃso Region
The ValparaÃso Region ( es, Región de ValparaÃso, links=no, ) is one of Chile's 16 first order administrative divisions.ValparaÃso Region, 2006 With the country's second-highest population of 1,790,219 , and fourth-smallest area of , ...
, and perhaps also in
Coquimbo Region
The Coquimbo Region ( es, Región de Coquimbo, ) is one of Chile's 16 regions (first order administrative divisions). It is bordered by Atacama to the north, ValparaÃso to the south, Argentina to the east, and the Pacific Ocean to the wes ...
and
Fray Jorge National Park from where there are a few sightings. The southern limit is generally accepted to be at about 55° latitude in
Tierra del Fuego
Tierra del Fuego (, ; Spanish for "Land of the Fire", rarely also Fireland in English) is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of the main island, Isla ...
.
Their movement patterns are not well resolved. Generally it seems to be sedentary, but there is a seasonal influx of Chilean hawks to NW Argentina. Perhaps they follow the swarms of migrant
passerine
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
s or even
Chilean pigeons (''Columba araucana''). It has been recorded as breeding in
Magallanes Province
Magallanes Province ( es, Provincia de Magallanes) is one of four provinces in the southern Chilean region of Magallanes and Antártica Chilena. The provincial capital is the city of Punta Arenas.
Geography and demography
Its eastern portion is l ...
but migrating away afterwards. Young birds seem to be quite prone to vagrancy: there is one certain and one possible record from
Tafà del Valle
Tafà del Valle is a city in Tucumán, Argentina. It is located in the department of the same name, of which it is the main settlement, in the west of the Argentine province of Tucumán, 126 km from the provincial capital, San Miguel de ...
and
Oasis de Pica, respectively; both locations are hundreds of kilometers north even of the suspected breeding range.
Ecology
The Chilean hawk is specifically found in
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
forest. Far more rarely, it is also found in
sclerophyll
Sclerophyll is a type of vegetation that is adapted to long periods of dryness and heat. The plants feature hard leaves, short internodes (the distance between leaves along the stem) and leaf orientation which is parallel or oblique to direct ...
ous forest, parkland and mixed forest and open habitat. Top hunt, it also visits open areas like shrubland, grassland or agricultural land to hunt. It is rarely if ever seen in heavily human-modified habitat however, and the few individuals that have been encountered in city parks and gardens are probably not resident birds. As it seems, it requires not much less than 200
hectare
The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is ...
s of native forest to breed.
Typically, forest inhabited by this bird is dominated by ''
Araucaria
''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen coniferous trees in the family Araucariaceae. There are 20 extant species in New Caledonia (where 14 species are endemic, see New Caledonian ''Araucaria ...
'' and
southern beech
''Nothofagus'', also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America (Chile, Argentina) and Australasia (east and southeast Australia, New Zealand, New Gu ...
(''Nothofagus''). Particular species that have been recorded are
coihue (''N. dombeyi''),
hualle (''N. obliqua'') and
lenga (''N. pumilio''). It probably tolerates some
logging, as long as the native character of the forest is not altered.
Secondary growth
In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...
with abundant mature trees remaining and dense undergrowth, e.g. of
South American mountain bamboo
''Chusquea'' is a genus of evergreen bamboos in the grass family. Most of them are native to mountain habitats in Latin America, from Mexico to southern Chile and Argentina.
They are sometimes referred to as South American mountain bamboos. Unli ...
(''Chusquea''), as caused by limited logging activity, may even be prime breeding habitat, although too little is known to be certain. When enough native forest is present,
plantation
A plantation is an agricultural estate, generally centered on a plantation house, meant for farming that specializes in cash crops, usually mainly planted with a single crop, with perhaps ancillary areas for vegetables for eating and so on. Th ...
s, e.g. of introduced
pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family (biology), family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanic ...
s, are also utilized.
During the day, it likes to perch on branches in its territory, moving between favorite areas of forest in low flight. Areas with strong human activity like settlements are approached cautiously; it is generally not a bird that announces its presence. Pairs split outside the breeding season; it is not studied whether they are monogamous only during the breeding season or for several seasons. It seldom
soars unrelated to reproductive activity. Males do aerobatic displays in courtship, such as a double loop resembling an upright "8".
The
louse
Louse ( : lice) is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result ...
''
Colpocephalum turbinatum
''Colpocephalum'' is a genus of chewing louse. Christian Ludwig Nitzsch named the genus in 1818. The Plenary Powers of the International Commission on Zoological Nomenclature selected ''Colpocephalum zebra'' as its type species in the 1950s. T ...
'' was found on a museum specimen of the Chilean hawk, but whether it actually
parasitize
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
s these birds or had simply crossed over from some other specimen is not known.
Food and feeding
It is not well known how this
carnivore
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...
catches its prey, but as it seems it is optimized for pursuit of small and maneuvrable birds throughout all levels of the forest. It is also able to seize large
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
s in mid-air. Both active searching for prey and sitting in ambush to wait what might come along has been observed. During the breeding season, pairs may cooperate in hunting; their different sizes ensures that they do not compete for prey much.
The Chilean hawk's food is almost exclusively birds (97.8% of all prey remains in one study),
[Figueroa Rojas ''et al.'' (2004)] in particular a diverse selection of forest
passerine
A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by th ...
s. More than 30 bird species are documented to be eaten by this hawk at least occasionally.
Rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are roden ...
s of at least 4 species and every now and then an occasional
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
or
squamate
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...
round off its diet.
The Chilean hawk hunts forest passerines quite indiscriminately of species, habitat or habits provided they have the right size, though it has a preference for species that live closer to the forest floor. Depending on availability, favorite prey species include
thorn-tailed rayadito (''Aphrastura spinicauda'')
black-chinned siskin
The black-chinned siskin (''Spinus barbatus'') is a species of finch in the family Fringillidae. Found in Argentina, Chile and the Falkland Islands, its natural habitats are temperate forests and heavily degraded former forest.
Description
The ...
(''Carduelis barbata''),
white-crested elaenia (''Elaenia albiceps''),
Austral thrush
The austral thrush (''Turdus falcklandii'') is a medium-sized thrush from southern South America. There are two subspecies, the Magellan thrush (''T. f. magellanicus'') from south Argentina and south and central Chile, and the Falkland thrush (' ...
(''Turdus falcklandii'') and
fire-eyed diucon
The fire-eyed diucon (''Pyrope pyrope'') is a passerine bird of South America belonging to the tyrant flycatcher family Tyrannidae. It is the only species placed in the genus ''Pyrope''.
It is 19–21 cm long. The upperparts are mainly pla ...
(''Xolmis pyrope'').
It has been claimed that the
Chilean pigeon (''Columba araucana'') constitutes important prey, but this seems only to be correct at certain times or places, if at all.
Reproduction
This hawk breeds in the
austral summer
Summer is the hottest of the four temperate seasons, occurring after spring and before autumn. At or centred on the summer solstice, the earliest sunrise and latest sunset occurs, daylight hours are longest and dark hours are shortest, wit ...
. Pairs apparently form from mid-late October on. Incubating birds have been observed in December, and chicks are seen from about
New Year's Eve
In the Gregorian calendar, New Year's Eve, also known as Old Year's Day or Saint Sylvester's Day in many countries, is the evening or the entire day of the December 31, last day of the year, on 31 December. The last day of the year is commonly ...
to February, after which the families disperse again. A 1937 nest and a 1945 egg description of the Chilean hawk appear to be based on a misidentification; the nest at least was probably of the
chimango caracara
The chimango caracara (''Milvago chimango'') is a species of bird of prey in the family Falconidae. It is found in Argentina, Uruguay, Chile, Paraguay and south of Brazil. The chimango is found as far south as Tierra del Fuego and is a vagrant ...
(''Milvago chimango'').
The oval platform nest measures about 50–80 by 50–60 cm and is some 25 cm high when freshly built. Some nests are more than twice as high; these might have been used in several years. It is built from strongly intertwined dry twigs and sticks. It is placed on forked branches in the upper part of a tree, close to the main trunk or a main vertical branch, some 16–20 m above ground. At least locally, full-grown
coihue trees (''Nothofagus dombeyi'') seem to be much preferred for nesting. Nests are sometimes reused in successive seasons, but more often a new nest is constructed in a different tree every season.
[Trejo ''et al.'' (2006), Figueroa Rojas ''et al.'' (2007)]
The
clutch
A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts ...
is probably two, sometimes three and rarely one, as usual for
Accipitridae
The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium- ...
. The eggs are dull light bluish to off-white all over and are shaped like a chicken's egg. The eggshell's inside has a slightly more pronounced bluish tinge. Incubation lasts probably about 3 weeks. The parents defend their nesting grounds against other birds of prey, such as the
red-backed hawk
The variable hawk (''Geranoaetus polyosoma'') is a polymorphic species of bird of prey in the family Accipitridae.
It is widespread and often common in open habitats in western and southern South America, including the Falkland Islands. Its ta ...
(''Buteo polyosoma''), and the
golden eagle
The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known birds ...
(''Aquila chrysaetos''); during approaches by such potentially dangerous species, the nestlings will tuck away their heads. It seems that 2 or 3 young are raised on a regular basis, unlike in many other Accipitridae where only the strongest nestling survives.
Status
Because of its forest habitat and secretive behaviour, the Chilean hawk is one of the least-studied raptors in the
Patagonia
Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and ...
n temperate forest. It is considered relatively common in the
Cape Horn
Cape Horn ( es, Cabo de Hornos, ) is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island. Although not the most southerly point of South America (which are the Diego Ramà ...
region, e.g. in
Ñuble National Reserve
Ñuble National Reserve is a national reserve of Chile located in the Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge o ...
, population densities as high as 4 birds per square km have been recorded. Elsewhere, it is far less often seen and usually quite rare. Attempts to assess its
population density
Population density (in agriculture: Stock (disambiguation), standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geographical ...
are hampered by the fact that it requires a certain amount of prime habitat to settle in a locale at all. Thus, much otherwise suitable land might be under-utilized by these birds, and
subpopulation
In statistics, a population is a set of similar items or events which is of interest for some question or experiment. A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypot ...
s have an extremely patchy distribution.
It is listed as a rare or insufficiently known species in
Chile
Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
and legally protected under the Hunting Law. In
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
it is not listed as threatened. On a global scale, it is a rare bird, though not under immediate threat. Populations may decline due to increasing habitat loss from extensive fires, logging pressures, and hunting.
It is not evaluated by the
IUCN, as they do not consider it specifically distinct, but is included on the
CITES
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
Appendix II as part of the blanket listing of
Falconiformes
The order Falconiformes () is represented by the extant family Falconidae (falcons and caracaras) and a handful of enigmatic Paleogene species. Traditionally, the other bird of prey families Cathartidae (New World vultures and condors), Sagit ...
.
Footnotes
References
* Figueroa Rojas, Ricardo A.; Alvarado Orellana, Sergio; Corales Stappung, Soraya & Shehadeh, Ishback (2004): Prey of breeding Chilean hawks (''Accipiter chilensis'') in an Andean ''Nothofagus'' forest in northern Patagonia. ''
Wilson Bull.'' 116(4): 347–351.
(HTML abstract)
* Figueroa Rojas, Ricardo A.; Alvarado Orellana, Sergio; Gonzalez-Acua, Daniel & Corales Stappung, Soraya (2007): Nest characteristics of the Chilean Hawk (''Accipiter chilensis'', Falconiformes: Accipitridae) in an Andean ''Nothofagus'' forest of northern Patagonia. ''Studies on Neotropical Fauna and Environment'' 42(1): 1-4
nglish with Spanish abstract (HTML abstract)
* Trejo, Ana; Figueroa Rojas, Ricardo A. & Alvarado Orellana, Sergio (2006): Forest-specialist raptors of the temperate forests of southern South America: a review. ''Revista Brasileira de Ornitologia'' 14(4): 317-330
nglish with Portuguese abstractbr>
PDF fulltext
External links
Accipiter Chilensis mating - Video by Emmy Award winner cinematographer Christian Munoz-Donoso
{{Taxonbar, from=Q114022
Chilean hawk
Chilean hawk
Birds of Chile
Birds of the Southern Andes
Chilean hawk
Chilean hawk