Sparrowhawk hawk ( Micrastur ruficollis ), brownish morph,
|( Vieillot , 1817)|
The Barred Forest Falcon ( Micrastur ruficollis ) is a carnivorous bird from the family of Falk-like . The species is a forest inhabitant of the tropical and subtropical regions of Central and South America. Due to their withdrawn way of life, the birds are rarely observed, but are easy to identify based on their typical call.
The sparrow hawk falcon is a rather small member of its family, whose physique is adapted to life in dense forests. The species has short, rounded wings that make it easier to navigate in flight in tight spaces. The tail and legs, on the other hand, are comparatively long in order to ensure better balance and faster locomotion on the ground and in trees. When fully grown, the birds reach a size of 33 to 38 cm, with a wingspan between 49 and 59 cm. Female sparrowhawk hawks are usually somewhat larger and heavier than their male counterparts, but in principle the two sexes are difficult to distinguish visually. Only a slight tendency towards a slightly grayish plumage in the male can be used in addition to the size differences.
Regardless of the slight sexual dimorphism , the species has two visually different morphs , which differ mainly in terms of the plumage on the upper side. In the gray morphs, the head and coat are dominated by slate gray tones interspersed with white dots, which gradually merge into brown tones on the wings. The brownish morph, on the other hand, shows reddish-brown tones on the back, which continue into the throat area. The basic color in the chest and stomach area is a creamy white in both forms, which, however, is traversed by many narrow, brown to black stripes. Towards the throat, this pattern changes into a uniform, pale gray. The control feathers on the tail, on the other hand, are black, with a white tip and three white to pale gray bars, which, however, are mainly recognizable in flight. The underside of the flight feathers is a pale gray, with a white bar at the base. The featherless parts of the body such as legs, wax skin and reins are bright yellowish to orange. The iris of the eye is yellow. The upper mandible of the short, strongly curved bill is gray, while the lower mandible is yellowish in color.
Young sparrowhawk falcons in their youthful dress are still rather dark brown to blackish on the head and coat, whereby this color becomes darker and darker towards the head, but is often interrupted by a white collar. On the wings and on the contour feathers on the upper side of the tail, the dark color is often streaked with lighter spots and stripes. The other tail feathers are blackish, with a white tip and three to four narrow, white bars, which are mostly more noticeable than in the adults . The underside and throat are cream-colored to yellow-brown with banding that varies depending on the individual. Young birds are probably no longer visually distinguishable from older specimens after the second complete moult , i.e. at the age of around two years. However, this assumption is based on only a few observations using scientific methodology and can therefore not be confirmed with absolute certainty.
Sparrowhawk falcons spend a large part of the day in the shelter of the forest, which makes direct observation of their behavior difficult. The species only very rarely undertakes extended gliding flights over the canopy of leaves. The birds can be heard much more often than seen, especially in the early morning and late evening hours, whereby their characteristic call facilitates clear identification. These vocalizations should sound like the barking of a very small dog and are uttered equally by both sexes. Sparrowhawks form lifelong pair bonds. Once a couple has found their own territory, the male actively defends it against intruders of their own species. They are asked to retreat with loud shouts and chase flights, but actual fights between sparrowhawk falcons for control of a territory have not yet been observed. The species is considered a resident bird in its entire range .
Sparrowhawk falcons feed almost exclusively on animal food, but are otherwise not picky about their prey. Depending on availability, lizards (especially of the genera Anolis and Ameiva ), arthropods such as spiders and insects, smaller birds and amphibians are preyed on. Occasionally, animals that are larger than the falcons themselves are beaten, such as wine doves ( Patagioenas plumbea ) and chestnut sinamus ( Crypturellus obsoletus ). Prey of this size then has to be consumed on the spot at an increased risk and cannot, as is usual, first be dragged by the birds to a safe place. Only in exceptional cases and exclusively during the breeding season has the supplementary intake of fruits been detected. During the hunt, the sparrowhawk hawks use various methods, the most common being the lurking from a seat guard . The birds wait for several minutes almost motionless at an exposed point below the canopy for prey that is passing by, which is then caught in a quick, direct pursuit flight. If no appropriate opportunity arises, the hide will be changed several times during the same hunt. Sometimes such large distances are covered within the territory before the hunt is finally successful. If available, the nests of other bird species, such as the hanging nests of various tyrants , are plundered and their nestlings are captured. The location of these nests is apparently acoustically based on the nestlings' begging calls. In general, large ear openings and a light spring ring in the face area - similar to that of a typical owl - indicate that hearing plays an important role in hunting. In other cases, sparrowhawk falcons shake branches and leaves with their feet to scare away hidden prey. The same effect has a chicken-like scratching with the claws on the ground, with which smaller prey such as insects in particular are to be tracked down. These are then followed running over short distances. A modification of this behavior is the search for swarms of driver ants (mostly of the genus Eciton ), which the birds then sometimes follow for several hours. Here it is not the ants themselves that are the target of the hunt, but the animals fleeing from the predatory raids of the ants, which are then easily captured by the sparrowhawk falcons. This hunting method is mainly used by younger specimens in the phase shortly after leaving the nest.
The courtship begins in large parts of the distribution area as early as February, up to two months before the start of the actual breeding season. Here the male sits on a singing station and calls his partner to him with loud chants. If this answers accordingly, the male flies to a potential nesting hole, where he then has it inspected by the female. If this shows interest by staying in the cave for a long time, the male goes on the hunt and then hands the prey over to his partner. Then in most cases mating occurs . Once a nesting site has been selected, the female spends more and more time in the immediate vicinity the closer the time of egg laying approaches, and relies more and more on the care of her partner. Other approaching birds are aggressively driven away.
Sparrowhawk falcons do not build their own nest; instead, they use caves in older, tall trees that have arisen naturally or that have been created by other species, such as woodpeckers . These provide a soft base made of decaying wood in which the eggs are laid. A deviation from this strategy is so far only known from a single case in Guatemala, where a couple chose a hollow in a rock cliff for their breeding business instead of a tree hole. It is unclear whether nests in rocky locations are used more frequently, since the reproductive behavior of the species has so far only been described in detail as part of a single study in the Guatemalan Tikal National Park , where there are no such cliffs. Once a nesting site has been finally selected, the female lays two to three eggs every 24 hours. These are quite large in relation to the body size of the birds, their average size is around 44 × 34 mm. The female is exclusively responsible for the incubation of the eggs, while the male provides his partner with food during this time. The male adult bird usually only re-enters the nest after the young have hatched; instead, the food is passed on to the female a few meters away from the nest cavity. The incubation period is 33 to 35 days, followed by a nestling phase of another 35 to 44 days until the offspring fledged. Immediately after hatching, the young birds are covered with a layer of soft, white down, their eyes are initially still closed and only open after two to three days. When potential threats approach the nest, the young sparrowhawk falcons show protective behavior shortly after birth, in which they lie motionless on the floor of the nest cavity and pretend to be dead. The male remains responsible for the food supply; the mother does not actively hunt again until the cubs are two weeks old, but the male continues to provide the overwhelming majority of the food. However, the prey is always handed over to the nestlings by the mother. After leaving the nest box, the offspring will continue to depend on their parents for some time and continue to beg them loudly for food. During this time, the young seldom move more than 50 m from their nesting tree. Only after another four to seven weeks do the young birds finally become independent and leave the territory of the adult birds. Young sparrowhawk falcons usually reach sexual maturity by the age of three, although isolated cases are known in which female specimens have hatched themselves in the first year after birth.
If the first brood is successful, there will be no further nesting processes in the same breeding season. However, if a first clutch is lost, for example through predation of the eggs or nestlings, breeding pairs occasionally start a second attempt at nesting, for which they then look for a new location. As with related species, the percentage of successful broods is comparatively modest and is only slightly more than 50%. The main reason for this is apparently the susceptibility of the cave nests to predation by climbing predators such as the gray fox ( Urocyon cinereoargenteus ) or the idol snake ( Boa constrictor ).
Spread and endangerment
The sparrow hawk falcon inhabits an extensive range in South and Central America, where it inhabits tropical and subtropical forest areas below about 2500 m. In the south it extends into the southernmost regions of Brazil and Paraguay, while in the west the Andes mountain range represents a natural boundary. In the north, the area is increasingly less contiguous, the northernmost records are known from the Caribbean coastal regions of central Mexico. Due to their hidden way of life in dense forests, direct sightings are seldom successful, which is why the species was not considered particularly common for a long time. More recent estimates, however, assume that the sparrowhawk forest falcon is significantly more common than previously assumed and is one of the most common predatory forest birds locally. Nevertheless, the increasing deforestation in particular poses a long-term threat to the survival of the species that depend on old, natural stands of primary forest for their survival . The IUCN currently classifies the sparrowhawk falcon at the lowest risk level of least concern , but the general population trend is declining.
The first description of the Barred Forest Falcon dates back to 1817 and is on the French ornithologist Louis Pierre Vieillot back, the first of the kind the scientific name Sparvius ruficollis awarded. Today, depending on the author, mostly six, less often seven, subspecies are considered valid, which are differentiated on the basis of their plumage and above all their vocalizations. The status of the northernmost population in the Mexican Sierra Madre del Sur as an independent subspecies is controversial; most authors currently consider this to be a slightly paler, clinical variation of M. r. guerrilla . The presence of different morphs in some, but not all of the subspecies makes the exact taxonomic classification of many specimens difficult, especially since other, very similar species from the genus of the forest falcon ( Micrastur ) occur sympatric in parts of the distribution area . For example, the two- banded forest falcon ( M. gilvicollis ), which is now regarded as a separate species, was a subspecies of the sparrowhawk forest falcon until the 1970s. Modern phylogenetic about investigations confirmed, a particularly close relationship of the Barred Forest Falcon with the lead-forest falcon ( M. plumbeus ) and the Minto Forest Falcon ( M. mintonii ). The separation of these four species took place very likely only a short time ago geological history within the Pleistocene . Within the genus of the forest falcon, they form a species complex named after M. ruficollis .
- M. r. ruficollis ( Vieillot , 1817) - Southern Brazil, Paraguay, and northern Argentina.
- M. r. concentricus ( Lesson , 1830) - Southern Venezuela, Guyana, and Amazonia . Slate gray on the top, whitish underside with black banding. The brownish color accents of the nominate shape are completely absent, and there is almost no banding on the tail.
- M. r. guerrilla Cassin , 1848 - Mexico and Nicaragua. Slate gray on top, with paler throat and back of the head. White underside with dark stripes.
- M. r. zonothorax ( Cabanis , 1866) - Eastern foothills of the Andes in Colombia and Venezuela as far as Bolivia. One of the dimorphic subspecies with a gray and a brownish variant. In both forms, the cheeks and throat are reddish-brown in color. The gray morph shows a slate-gray back and a white-black striped underside. The brownish morph is generally darker, with a cinnamon-colored stain on the upper chest.
- M. r. interstes Bangs , 1907 - Costa Rica, Panama, western Columbia and western Ecuador. Similar coloring to M. r. guerrilla , only slightly darker, but with significantly longer tail feathers.
- M. r. olrogi Amadon , 1964 - Northwest Argentina. Also dimorphic with variants similar to the nominate form, but larger and with a slight tendency to more brownish plumage.
- M. r. oaxacae Phillips, AR , 1966 - Mexican state of Oaxaca . Generally a little paler than M. r. guerrilla , on the tail feathers almost no white is recognizable.
- Russel K. Thorstrom: Neotropical Birds of Prey: Biology and Ecology of a Forest Raptor Community . Ed .: David F. Whitacre. Cornell University Press, Ithaka / London 2012, ISBN 978-0-8014-4079-3 , pp. 234-249 .
- Recordings of various vocalizations at xeno-canto.org
- Steve NG Howell, Sophie Webb: A Guide to the Birds of Mexico and Northern Central America . Oxford University Press, Oxford 1995, ISBN 978-0-19-854012-0 , pp. 214 .
- Thorstrom, pp. 234-235
- James Ferguson-Lees, David A. Christie: Raptors of the World . Christopher Helm, London 2001, ISBN 978-0-7136-8026-3 , pp. 815 .
- Thorstrom, p. 245
- Thorstrom, p. 234
- Thorstrom, p. 243
- James Ferguson-Lees, David A. Christie: Raptors of the World . Christopher Helm, London 2001, ISBN 978-0-7136-8026-3 , pp. 813 .
- Thorstrom, pp. 235-236
- Fábio Röhe, André Pinassi Antunes: Barred Forest Falcon (Micrastur ruficollis) Predation on Relatively Large Prey . In: The Wilson Journal of Ornithology . tape 120 , no. 1 , 2008, p. 228-230 , doi : 10.1676 / 05-141.1 .
- James Ferguson-Lees, David A. Christie: Raptors of the World . Christopher Helm, London 2001, ISBN 978-0-7136-8026-3 , pp. 814 .
- Thorstrom, pp. 239-240
- Thorstrom, p. 238
- Aaron J. Baker, Oscar A. Aguirre-Barrera, David F. Whitacre, Clayton M. White: First Record of a Barred Forest-Falcon (Micrastur rufficollis) nesting in a Cliff Pothole . In: Ornitologia Neotropical . tape 11 , 2000, pp. 81-82 .
- Thorstrom, pp. 240-241
- Thorstrom, p. 242
- Thorstrom, pp. 245-246
- Thorstrom, pp. 247-248
- Species factsheet: Micrastur ruficollis. In: datazone.birdlife.org. IUCN, 2021, accessed May 6, 2021 .
- Barred Forest-Falcon Micrastur ruficollis (Vieillot, 1817). In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .
- Allan R. Phillips: Further systematic notes on Mexican birds . In: Bulletin of the British Ornithologists' Club . tape 86 , no. 1 , 1966, p. 91 .
- Paul Schwartz: Micrastur gilvicollis, a Valid Species Sympatric with M. ruficollis in Amazonia . In: The Condor . tape 74 , no. 1 , 1972, p. 399-415 , doi : 10.2307 / 1365892 .
- Leonardo Moura dos Santos Soares, John Bates, Lincoln Silva Carneiro, Marcos Pérsio Dantas Santos, Alexandre Aleixo: Molecular systematics, biogeography and taxonomy of forest falcons in the Micrastur ruficollis species complex (Aves: Falconidae) . In: Journal of Avian Biology . tape 50 , no. 4 , 2019, doi : 10.1111 / jav.01943 .
- Barred Forest-Falcon (concentricus) Micrastur ruficollis concentricus (Lesson, 1830). In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .
- Barred Forest-Falcon (guerilla) Micrastur ruficollis guerilla Cassin, 1848. In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .
- Barred Forest-Falcon (zonothorax) Micrastur ruficollis zonothorax (Cabanis, 1866). In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .
- Barred Forest-Falcon (interstes) Micrastur ruficollis interstes Bangs, 1907. In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .
- Barred Forest-Falcon (olrogi) Micrastur ruficollis olrogi Amadon, 1964. In: avibase.bsc-eoc.org. Retrieved May 5, 2021 .