Swallow consecration

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Swallow consecration
Elanoides forficatus02.jpg

Schwalbenweih ( Elanoides forficatus )

Systematics
Order : Birds of prey (Accipitriformes)
Family : Hawk species (Accipitridae)
Subfamily : Honey buzzards (Perninae)
Genre : Elanoides
Type : Swallow consecration
Scientific name of the  genus
Elanoides
Vieillot , 1818
Scientific name of the  species
Elanoides forficatus
( Linnaeus , 1758)

The Schwalbenweih ( Elanoides forficatus ) is a species of raptor from the subfamily of the honey buzzards (Perninae) and the only species of the genus Elanoides . It is unmistakable due to its black and white plumage and the kite-like flight pattern with the deeply forked tail. The very large main distribution area extends over tropical South America . In addition, the species occurs in Florida , some neighboring states on the Gulf of Mexico and in large parts of Central America .

description

Typical flight image
Two consecrated swallows have perched on a tree
Schwalbenweih in search flight

With a body length of 52–62 cm and a wingspan of 119 to 136 cm, the Schwalbenweih is about the size of a black kite ; the tail measures 28-37 cm. The flight image with the long, pointed wings and the very deep tail, forked over more than half the length, can at best be confused with the magnificent frigate bird within the distribution area . However, the small head with the fine beak and the missing orbital ring around the eye looks like a dove. The legs and feet are delicate with a short tibiotarsus . The sexes do not differ externally, but females are on average 3%, in the north of the distribution even 8% longer-winged than males.

The beak is black, the wax skin dark blue-gray. The iris is red. The head, neck, underside, under wing-coverts and axillary feathers are white. The back, upper wing coverts, wings and control feathers are blue-black, with the shoulder feathers, the marginal coverts and the small upper arm coverts shimmering metallic purple, lavender, greenish or bronze colored. The rest of the black areas appear dusty blue-gray. In sitting birds, due to the predominantly white upper arm wings and the white bases of the arm wings, seemingly irregular, white areas can be seen on the back. Legs and feet are light blue-gray.

Young birds are very similar to adult birds, but with shorter tails. The iris is red-brown here. The black areas are dull black or slightly brown-black or greener in the northern subspecies. Narrow white point hems of the upper wing coverts, wings and control springs are completely worn away after six to nine months. The head and chest can have a yellowish beige tint and be interspersed with fine, black lines.

voice

The Schwalbenweih is usually not very shouting. Only during express flights, at the nest (especially in the event of malfunctions) and at the evening gathering of sleeping societies is increased call activity recorded. The calls are high and whistling, usually sounding a bit weak, but sometimes they can be heard piercingly loud and far. It is mostly a multisyllabic series. A loud klie-klie-klie is described as an alarm call . A long, rising tju-wieh can be heard during courtship flights and during copulation. When handing over food, when changing partners at the nest or as a begging call in various contexts, a monosyllabic or long-spaced ieep is uttered . A faint chirping was noticed when leaving bed societies in the morning.

Systematics

The swallow consecration was first described by Carl von Linné in his Systema naturae as Milvus forficatus in 1758 . Louis Pierre Vieillot placed it in a monotypical genus Elanoides in 1818 . The Schwalbenweih belongs to the subfamily of the honey buzzards (Perninae) and forms the sister taxon of the crested buzzards ( Aviceda ), which live in the tropics of the Old World .

Geographic variation

Two subspecies are recognized that can be distinguished by the structural colors of the dorsal plumage. The northern subspecies shines more purple to violet, the southern greenish to bronze colored. In addition, the North and Central American nominate form is on average more long-tailed.

  • E. f. forficatus ( Linnaeus , 1758) - coastal areas in the southeastern United States to northern Mexico.
  • E. f. yetapa ( Vieillot , 1818) - southern Mexico with the exception of Yucatán southwards through Central America to eastern Bolivia, Paraguay and northeast Argentina.

distribution

The brood distribution of the swallow harrier extends over large parts of the Neotropical Region and a small part of the Nearctic . In the 19th century, however, the area there expanded over large parts of the southeastern and central United States. The species was distributed here in the coastal plains on the Gulf of Mexico and over large parts of the Mississippi system northwards to Minnesota .

Today the breeding occurrence in the USA is limited mainly to the Florida Peninsula and the coastal plains in South Carolina and in southeastern Georgia . Other scattered occurrences are found on the Florida Panhandle , southwest Alabama , southeast and southern Mississippi , southeast and central southern Louisiana, and east Texas . After 1970 there was still suspicion of breeding in North Carolina .

Apart from very sparse evidence of breeding in eastern Mexico, the distribution area only continues 1500 km further south. It ranges from Chiapas in southern Mexico to Central America, where the species is rare north of Costa Rica and almost absent on the Pacific coast.

The main distribution area extends over the northern two thirds of South America. The southern border runs through Ecuador and the northeastern part of Peru , includes the north and east of Bolivia and the west of Paraguay , and runs through Rio Grande do Sul to the Atlantic. In addition, the area extends into Argentina in the northwest and northeast . A southern enclave is located on the Río de la Plata in Uruguay and Argentina. In Colombia and Venezuela , the species is absent in some parts of the country. She is relatively common in Trinidad .

hikes

The swallowtail populations north of 10 ° N and south of the Tropic of Capricorn are migratory birds that overwinter in tropical South America. The native birds there also roam outside of the breeding season. Breeding birds from the mountains usually migrate to lower elevations.

The breeding birds of the USA, Central America and Trinidad migrate south between July and September; the homecoming takes place between January and March. They use two routes, one through Texas, Mexico and the Central American Atlantic coast, the other through Cuba , Jamaica and the Caribbean Sea .

In North America, the species can still be observed as an irregular guest westwards to Colorado and northwards to southern Canada - sometimes up to November. She was found to be a random visitor on Fuerteventura .

habitat

The Schwalbenweih inhabits various semi-open landscapes, forest edge zones or larger clearings. Particularly dry areas are avoided. The structuring of the landscape is more important than certain vegetation communities or habitat types. In addition to tall, freely accessible trees as nesting sites, there must be open areas for flight hunting that offer a rich supply of food. Typically, the species occurs in wooded areas or forest islands in the savannah, as well as in lighter areas or on the edges of moist forests that border cypress or mangrove swamps or wet grassland. Especially in the tropics, denser forests are also populated with enough clearings. The altitude distribution is usually less than 500 m, but if the climate is sufficiently humid, the swallowtail also settles in higher altitudes - up to 1600 m in Mexico and Central America or up to 3500 m in the Andes. Exceptionally, the species can still be found there at altitudes between 4000 and 5000 m.

behavior

Schwalbenweih spends most of the day in the air. He only sits down in the morning and evening hours and when it rains. You can usually observe the species gliding, standing in the wind or hunting low over the vegetation. The flight is described as very elegant, agile and sometimes jiggling. The deep, sluggish flapping flight is rarely used. When the Schwalbenweih sails in thermals , it often reaches greater heights than New World vultures or buzzards. Landing maneuvers often seem a bit awkward. When taking off, the bird typically loses altitude, glides with its wings half open until it has the necessary speed, and then spreads its wings to soar.

The Schwalbenweih is very sociable and, especially outside the breeding season, larger sleeping societies or flocks of 10 to 50 birds form in places with good food supply. The largest sleeping societies form before the autumn migration and can include several hundred birds. At the largest mass sleeping place to date, over 2000 swallow consecrations were counted. Accumulations of 50 specimens or up to several hundred specimens on isthmuses can be observed on the train. Often, the way then associated with the Plumbeous Kite ( Ictinia plumbea ).

Harriers often leave their roosts relatively late (up to 2 hours after sunrise) and return shortly before or during sunset. Especially in the morning, some time is devoted to feathers care and it is not uncommon for the birds to sunbathe with outstretched wings and feathers. During the breeding season, they can often be seen near the nest when caring for their plumage. During flight or when taking off from the nest after brooding, a bird may shake and drop down a little to ventilate and organize its plumage. Sometimes flying birds touch the surface of the water to wet their belly. This is probably used for cooling.

nutrition

The Schwalbenweih feeds primarily on larger flying insects such as grasshoppers , dragonflies and beetles , but also on smaller, swarming species such as termites and ants . In addition, there are frogs , smaller, mostly arboreal lizards and adders, insect larvae, bird eggs and nestlings. Small birds such as hummingbirds , bats or small fish are far less prey and fruits are eaten. The composition of the food spectrum depends heavily on local conditions. While in Florida the food consisted largely of insects, frogs and nestlings, in Guatemala almost only insects and hardly any frogs were found as prey. While fruit consumption has not been observed in the USA, it is not uncommon in the tropics.

The prey is captured only from flight and is almost always grabbed with the feet. It is often small and difficult to make out, but easy to grasp. In an extremely elegant and sometimes very agile flight, the species hunts sailing over the treetops, over bushes, grasslands and swamps. The bird corrects the direction with constant movements of the tail, makes quick changes of direction and turns, drops steeply for a short time or lets itself fall into the vegetation. Sometimes the prey is caught in a short shaking flight . Adult birds consume their prey in flight and rarely perch on trees or branches during the day. However, food is always given to a partner or boy while sitting and never in flight. During the breeding season, search flights over the vegetation can be observed in the morning and late afternoon, while the hot hours of the day are used to hunt insects at higher altitudes.

Reproduction

It is uncertain at what age the harrier swallows reproduce, and whether birds brood in the first year of life is a matter of controversy. The species is apparently monogamous , but no observations have been made on the length of pair relationships. There is an annual brood.

The start and duration of the breeding season vary depending on the geographical location. In Florida it is between March and July, in Central America it begins in March at the latest. In Costa Rica it is between January and August.

The couples will probably already find each other on the train or stay with the previous year's partner. They behave territorially only in the immediate vicinity of the nest within a radius of 50 to 100 m, so that there can be accumulations of several nests in suitable locations within a few hundred meters. Circling, silent expressive flights can be observed over the nesting site in 25–100 m. However, intruders are sometimes evicted with shouts and brief swoops or pursuits. It is not entirely clear whether such flight maneuvers and calls can also be related to courtship. Copulation is usually initiated by begging for food by the female, who is then supplied with food by the male and flown around in a circle until it lands on the female's back, copulates and then drops forward and flies off calling.

The nest is usually relatively open and on very small branches at heights between 8 and 60 m in the crown of a tree. In the USA, the majority of these are pines, less often other conifers or deciduous trees. The nests are relatively small with a diameter of 30–60 cm, often just a thin platform, but mostly around 10–30 cm high. The exterior consists of branches; the nest cavity is lined with lichen , Tillandsia usneoides , pine needles, strips of bark, moss or other parts of the plant. Both partners participate in the construction. Often a nest from the previous year is repaired first, but then a new one is built nearby before the eggs are laid.

The clutch usually consists of 1–2, more rarely up to four creamy white to white, dark brown to reddish dark brown speckled eggs of about 48 × 38 mm in size, which are incubated for between 28 and 31 days.

The nestlings are almost continuous and mostly in the first week of females brooded . After a week, the male no longer roams, but only carries food. Up to the third week, the young are still fudged by the female at night and occasionally shielded from excessive sunlight during the day.

In the first half of the nestling period, food is only brought by the male. It passes the prey at the nest to the female, who divides the prey and feeds it to the young until they are two or three weeks old. Then the female also participates increasingly in the food supply.

Young swallow harriers fly out between 35 and 57 days of age. Before they dare to make real flights into neighboring trees, they practice jumps and flights to branches near the nest for 1–3 days.

The number of broods in which more than one young flew out varies between 41% in Guatemala and 72% in South Carolina . With three nest siblings, in each case observed, at most two survived, the youngest died in each case. In some cases, kainism has been found in broods with two nestlings .

Duration

There is no information available about the total stock, it is estimated that it is in the hundreds of thousands. In many places the species is described as rather frequent, the population trend is partially positive and although increasing deforestation in South America is having a negative effect, the swallow pond is apparently far less affected than other bird of prey species. Due to the large distribution area of ​​over 12 million km², it is not considered threatened by the IUCN .

In the USA, the population is estimated at 800 to 1150 breeding pairs, or including non-breeders and current offspring at 3200 to 4600 individuals after the breeding season. The species was subject to a sharp decline between 1880 and 1940, which led to its extinction in large parts of the original range. While it previously occurred in the Mississippi Basin northwards to Minnesota and in the southeastern coastal plains, the majority of the population is now limited to Florida and South Carolina. There are some smaller occurrences in surrounding coastal states. Reasons for the decline were probably the increasing management and deforestation of the floodplains and plains and, to a lesser extent, hunting. Apart from local fluctuations, the stock currently appears stable. Protection efforts concentrate primarily on the preservation of suitable habitats and the protection of larger sleeping places from the autumn migration.

literature

Individual evidence

  1. ↑ Ferguson-Lees / Christie (2009), p. 110, see literature.
  2. ↑ a b Meyer (1995), section Distinguishing Characteristics , see literature
  3. ↑ a b c d e f g h i j Ferguson-Lees / Christie (2001), p. 348, see literature
  4. ↑ a b c d e Ferguson-Lees / Christie (2001), see literature
  5. ↑ Schwalbenweih, alarm call audio sample
  6. ↑ Meyer (1995), section Sounds , see literature
  7. ↑ Anett Kocum: Phylogeny of the Accipitriformes (birds of prey) on the basis of various nuclear and mitochondrial DNA sequences. Dissertation, University of Greifswald, 2006, p. 109.
  8. ↑ a b c Meyer (1995), section Distribution , see literature
  9. ↑ Hartmut EJ Müller, Kathrin Lippert: Schwalbenweih Elanoides forficatus on Fuerteventura - a new species for the Palearctic , Limicola - magazine for field ornithology, Volume 12, 1998, pp. 80-84
  10. ↑ Meyer (1995), section Distinguishing Characteristics , see literature
  11. ↑ a b c d e f Meyer (1995), section Behavior , see literature
  12. ↑ a b c Meyer (1995), section Food Habits , see literature
  13. ↑ a b c d e f Meyer (1995), section Demography and Populations , see literature
  14. ↑ a b c d e f g Meyer (1995), section Breeding , see literature
  15. ↑ Meyer (1995), section Conservation and Management , see literature

Web links

Commons : Schwalbenweih  - Collection of images, videos and audio files