Smooth-beaked ani
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Smooth-billed ani ( Crotophaga ani ) |
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| Linnaeus , 1758 |
The smooth- beaked ani ( Crotophaga ani ) is a member of the genus Crotophaga within the cuckoo family (Cuculidae). The black, conspicuously long-tailed bird occurs in large parts of South America, on almost all islands in the Caribbean and in some areas of Florida and Central America . Its characteristic reputation gave the common names of the genus its name in some languages and forms the specific epithet for this species . Smooth-billed anise feed mainly on insects, which they pick up from the ground, but also prey in bushes and on trees. Like the other two species of the genus Crotophaga , smooth-billed anise are not brood parasites , but primarily community breeders . Usually several females lay their eggs in a jointly built nest and raise the young together with other group members. The monotypic species is common in places and its population is not endangered. In some areas along the Central American and South American Pacific coast, it spreads strongly and sometimes displaces the Riefenschnabelani there .
Appearance
Smooth-billed anises are around 35 centimeters long, of which a good half is accounted for by the tail, slightly larger than the very closely related deep-billed anise. So they are about the size of city pigeons , but significantly lighter than these. Males of this species weigh an average of 110 grams, the slightly lighter females 93 grams. The differences in size between the sexes are insignificant and there is no color dimorphism . The best distinguishing feature, which can only be used up close, is the male's greater beak height.
Smooth-billed anises are uniformly black birds with a very long tail, widened towards the tip, which is often pointed upwards, especially at the bottom. The plumage has a bronze-brownish sheen on the neck, the feather edges on the back have a bluish shimmer and those of the wing-coverts are purple. The neck feathers often stick out a bit. The edges of the broad, long tail feathers sometimes have a bluish sheen, like the dorsal plumage. As with all aniseed, the beak looks compressed to the side. In older males, the upper bill is raised like a comb, so that it forms an edge on the top. Its ridge towers over the top of the head. The beak edges are smooth, in older individuals also cracked or slightly furrowed. Females have a slightly less powerful beak. The iris is dark brown or black. The strong feet, toes and claws are also black.
Immature smooth-billed anise largely resemble adult. However, they largely lack the plumage, the beak is less powerful, the beak crest is not fully developed.
Smooth-billed anise and Rief-billed anise occur together in large areas. Their field ornithological differentiation is often difficult, but is made much easier by the clearly different calls that can be heard almost all the time. Immature birds are often difficult to identify with certainty. In adults, the shape of the beak, or the presence or absence of beak notches, is a reliable differentiator. The shine of the plumage, in particular the head and neck plumage, can provide additional help: with smooth-billed anise this shimmers bronze-brown, with deep-billed anise blue-turquoise.
voice
Like all aniseed, this species is also very noticeable acoustically. Your vocal repertoire is large. Characteristic is a long, high, slightly whimpering, pressed-sounding Aaji , which is uttered at different intervals, often in sequences of calls or in quick groups. The second syllable is pronounced in ascending order and accelerated. This reputation gave the genus its name in many languages and is also circumscribed by the specific epithet . In addition, a variety of chuckling, cackling, meowing and croaking sounds can be heard in group and partner communication. 13 different utterances were assigned to different social situations.
distribution and habitat
The range of the smooth-billed anise is very large. It stretches from the Florida Peninsula across the Bahamas , the Greater and Lesser Antilles, southward to northern Argentina.
In Florida, the species is widespread in the south of the peninsula, to the north the occurrence extends to about Palm Beach . Some island deposits are further north and inland. Flat-billed anise is common in the Bahamas, the Greater Antilles, the Cayman Islands , the Virgin Islands, and Providencia , as well as St. Vincent , Dominica, and Grenada . The species is also widespread in Trinidad , but rarely in Martinique and Guadeloupe . In some years, smooth-billed anisees breed on many small islands and are then absent again for a longer period of time.
In Central America the species only breeds sporadically in some areas of the Yucatan , especially on the islands off the peninsula, more frequently and in more closed areas on the Pacific coast of Costa Rica and Panama and south-east of the channel region throughout Panama.
In South America, the breeding occurrences of the species are mainly east of the Andes and extend south from the South American Gulf and Atlantic coast across Colombia , Venezuela , Brazil , Paraguay and Uruguay to northern Argentina . East of the main Andean chain, the species is also breeding bird in Ecuador , Peru and Bolivia . To the west of the Andes chain, a narrow distribution area extends along the Colombian Pacific coast to northernmost Peru.
The species has been found on the islands of the Galápagos Archipelago since the 60s of the last century , first on Isabela , today on almost all islands. The exact circumstances of its occurrence are not known, but it is believed that the species was introduced, possibly with the intention of reducing the tick infestation in cattle herds. Today one is very skeptical about the spread of the smooth-billed anise in the Galapagos and there are considerations to regulate the population or to extinguish it completely on some islands.
Flat-billed anise inhabit a variety of moderately moist to moist habitats. They are quite adaptable in their choice of habitat and also penetrate into the immediate vicinity of human settlements, where they find breeding opportunities, for example, in tree-lined meadows, parks, golf courses, on the edge of plantations or at roadsides. Smooth-billed anise are often among the first birds to colonize freshly cleared land. Natural habitats are primarily secondary bushland, extensive forest clearings, secondary forests, especially populations with ant trees, woody trees that accompany rivers, peripheral areas of standing water, mangroves , but above all loosely tree-lined savannas and extensive, extensively used pastures. Flat-billed anise occurs mainly in lowlands and at heights of up to 500 meters, breeding sites at over 2000 meters are known from Venezuela , Colombia, Ecuador and Peru.
Space requirements
Flat-billed anise are strictly territorial, at least during the breeding season, the resident populations throughout the year. A territory includes the nesting tree, sleeping trees and areas for foraging. It is mainly defended against conspecifics and crested anise, while giant anise is tolerated. The size of the territory depends on the size of the group. In groups with three adults 6.2 hectares were found, 5 adults need 8.7 hectares and 6-9 adult group members 9.6 hectares.
hikes
Smooth-billed anise are resident birds. Most populations remain in their territories throughout the year. Small-scale hikes in wetter areas during the seasonal dry seasons occur. Then several groups can unite and temporarily form quite large societies of thirty or more individuals. The frequent presence of flat-billed anise on the Dry Tortugas suggests that migrations take place between Florida and Cuba . In contrast to the Riefenschnabelani, smooth-billed anise are rarely seen outside of their breeding grounds in the USA.
Food and subsistence
Flat-billed anise feed themselves and their young mainly on insects. Locusts make up the largest proportion of these. In addition, every available other species, such as fishing rods , mole crickets , cockroaches , beetles , including a number of weevils that can pest insects in sugar cane plantations and citrus groves, butterflies and their caterpillars and dragonflies, is eaten. Even spiders , woodlice and worms are part of the food spectrum. Occasionally, these aniseed prey on small mammals, reptiles , amphibians , birds and their eggs, as well as snails and fish. Overall, the animal food component is over 90 percent. Fruits, seeds and berries play a certain role, especially in the respective dry seasons.
The food is read on the ground or from low vegetation, but is also sought in bushes, on branches or in the leaves of trees. Hunting strategies also include flight hunts for swarming insects and short flights to catch fleeing species. Flat-billed anise seek to get close to herd animals and capybaras in order to capture the insects they scare off, or to peck blood-sucking insects and ticks directly from the animals. They follow armadillos and trains of driver ants to prey on insects and other fleeing small animals. In search of bottom organisms, they poke the surface of the ground and also look for prey in the dung.
behavior
Flat-billed anise are diurnal. Your activity time roughly corresponds to the length of the day. The activity peaks are in the morning hours until around 11 a.m. and range from late afternoon to sunset. During the hot midday hours, they usually rest in the shade of bushes or trees. In the morning they spend some time sunbathing, raising their plumage and spreading their wings. On the ground they walk or run in pursuit of prey or hop on both legs. Nestlings that have not yet fledged can climb through the branches with the help of their beak and claws. The flight is straight and not particularly fast. Some rapid wing beats are followed by a glide phase. In groups, the birds fly one behind the other in a line.
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Like all aniseed, they are highly social birds. They often sleep next to each other in physical contact, search for food together and can often be seen caring for their plumage. The defense against rival groups of conspecifics or potential enemies or nest robbers also takes place jointly. The groups consist of one pair or more largely monogamous pairs as well as some unpaired adult birds and the young birds of a breeding season. They usually include no more than 11 individuals, but occasionally up to thirty. Single breeding pairs are rare. Within the groups, the couples form special, closer units. Occasionally Glattschnabelanis are in search of food with Carolina pigeons and great-tailed grackle socialized, mockingbirds , Gray King tyrant , Cory cuckoos and Kubastärlinge and other species of this genus are, however, attacked and expelled from the territory.
Actions of aggression are mainly limited to loud shouts and chase flights. However, fierce contact fights can occur between conspecifics, which can result in injuries. There are indirect indications that these can also be fatal.
They quietly flee to safe cover from predators who can pose a direct threat to adult smooth-billed anise. From ground enemies and climb countries enemies such as snakes, possums , raccoons , martens , cats and rats , as well as before crows warn loudly and attack the invaders by swoops directly. People can also be attacked directly near the nest.
Breeding biology
Flat-billed anise become sexually mature as yearlings, but often only breed a year later. They form largely monogamous partnerships that can last for one season or longer. Polygyny and polyandry occur rarely and are usually triggered by the death of a couple. Extra couple copulations are also rare, as far as known. The mating takes place mainly in the nest tree or in the nest itself, usually the male gives the female a bride present. Usually the male mounts the female, but copulations in the reverse order have also been observed.
Like their relatives, smooth-billed aniseed are community breeders, but the breeding competition between the pairs, which is present in all aniseed, is very pronounced in this species and in individual cases can result in very violent contact fights. When a nest is destroyed, females ready to lay try to lay their eggs in the group nests of neighboring groups.
The nesting place is selected by part of the group and indicated with loud shouts. It can happen that another subgroup prefers a different location and is built on two nests at the same time. Usually, however, the group decides on a nesting place and builds the nest with the participation of all members in one to two weeks. It is a massive construction made of twigs, vines and stalks, lined with soft materials on the inside. It has an outer diameter of up to 30 centimeters and an inner diameter of up to 20. The depth of the bowl varies between 5 and 9 centimeters. The nests are usually relatively low in dense, preferably thorny bushes or trees.
Laying begins in Florida in May; in areas with seasonal rainy seasons, eggs are laid shortly after they begin; in those without rainy seasons, breeding can take place at any time of the year. Two annual broods are the rule, three not uncommon. Apparently the lowest-ranking female begins laying eggs. The next female often removes the eggs, but more often she covers them with large leaves and lays her own eggs on top. The next one does the same. This can result in very large clutches, some with over 30 eggs have been found. However, only the top layer is hatched. Fighting can be fierce when females attempt to bring their own eggs back to the surface. The last clutch is often guarded by its female. It hardly leaves the nest and is fed until the chicks hatch. The highest number of layers of buried eggs was found in a nest in Puerto Rico. It contained 8 layers with 22 dead eggs and 7 nestlings. In the case of community broods, the first eggs usually do not hatch. The clutch sizes range from 4.3 eggs for one female, 9.5 for two females, 14.8 for three females and 21.3 eggs for four females. The greenish-blue eggs, coated with a whitish, translucent layer of lime and measuring 35 × 26 millimeters, weigh 11.5 grams, so they are very large and heavy for a bird of this size. The couple whose female laid last takes care of most of the hatching business, assisted by other group members. During the night, the dominant male always seems to breed. The breeding period is 13-14 days. If eggs hatch from earlier than last laid clutch, the development deficit of the most recently hatched chicks is sometimes so great that they cannot cope with the nestling competition and perish. The young are hovered, shaded and provided with food by all family members, including the young birds from previous broods. They develop very quickly and leave the nest at the earliest 10 days, but usually a little later. At this age they are capable of short, fluttering flights, they become fully airworthy at around three weeks. They stay in the family group for 8 months to a year before they migrate .
Breeding success and life expectancy
The breeding success and the reproduction rates per breeding pair are low. The key factor here is the incubation system, which excludes more than half of the eggs laid from successful incubation, and the high nestling mortality due to nestling competition, diseases and nest predators. The highest reproduction rates are in 4-pair groups, with around 1.4 young birds per female reaching an age of 20 days.
No information is available on the life expectancy of the smooth-beaked ani.
Systematics
The species belongs to the small genus Crotophaga , to which the Riesenani and the sister species Riefenschnabelani also belong. Sister genus is the monotypical genus Guira , which is restricted to South America and has only one species. The three Ani species and the Guirakuckuck form the subfamily Crotophaginae. The species is monotypical, no subspecies are described.
Persistence and Threat
The Glattschnabelani has a very large distribution area of over 14 million square kilometers. The population is estimated at 20 million adult birds. Global population trends do not exist, but the species seems to benefit from the extensive clearing of primary forests that are taking place in its range. It is therefore not considered endangered. The slight decline in stocks in Florida is attributed to the extensive use of insecticides.
literature
- Francisco Erize, Jorge R. Rodriguez Mata, and Maurice Rumboll: Birds of South America. Non Passerines: Rheas to Woodpeckers. Princeton Illustrated Checklists. Princeton University Press, Princeton and Oxford 2006, ISBN 0691126887 , pp. 240-241.
- James S. Quinn and Jennifer M. Startek-Foote: Smooth-billed Ani (Crotophaga ani). In: The Birds of North America Online (A. Poole, Ed.). The Cornell Lab of Ornithology, Ithaca 2000 (online).
- Robert B. Payne: The Cuckoos. In: Bird Families of the World . No. 15, Oxford University Press, 2005, ISBN 0198502133 , Plate 1, pp. 6 and 174-178.
Individual evidence
- ^ Robert B. Payne (2005) p. 180
- ^ Robert B. Payne (2005) p. 180
- ↑ Payne (2005) p. 175
- ↑ Quinn and Startek-Foote (2000) Conservation and management
- ↑ Conservation and restoration of island ecosystems ( Memento of the original from November 17, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Payne (2005) p. 175
- ^ Payne (2005) p. 176
- ↑ Quinn and Startek-Foote (2000) Behavior
- ↑ Quinn and Startek-Foote (2000) Behavior
- ↑ Payne (2005) p. 175
- ↑ Quinn and Startek-Foote (2000) Migration
- ↑ Quinn and Startek-Foote (2000) Diet
- ^ Payne (2005) p. 176
- ↑ Quinn and Startek-Foote (2000) Social And Interspecific Behavior
- ↑ Quinn and Startek-Foote (2000) Agonistic Behavior
- ↑ Quinn and Startek-Foote (2000) Sexual Behavior
- ↑ Payne (2005) p. 177
- ↑ Quinn and Startek-Foote (2000) Nest
- ^ Payne (2005) p. 178
- ↑ Payne (2005) p. 134
- ↑ Quinn and Startek-Foote (2000) Nest
- ↑ Quinn and Startek-Foote (2000) Breeding
- ↑ Quinn and Startek-Foote (2000) Demography and Populations
- ↑ Michael D. Sorenson and Robert B. Payne: A molecular genetic analysis of cuckoo phylogeny . In: Robert B. Payne: The Cuckoos (2005)
Web links
- Crotophaga ani in the Red List of Threatened Species of the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 2 of 2009.
- BirdLife International: Species Factsheet - Smooth-billed Ani ( Crotophaga ani ) . Retrieved January 2, 2012.
- Videos, photos and sound recordings for Crotophaga ani in the Internet Bird Collection
- Smooth- beaked ani ( Crotophaga ani ) at Avibase; Retrieved January 2, 2012.
- xeno-canto: Sound recordings - Smooth-billed Ani ( Crotophaga ani )