Bloodbeak weaver

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Bloodbeak weaver
A male of the bloodbeak weaver of the subspecies Q. q. quelea in brood plumage on nest

A male of the bloodbeak weaver of the subspecies Q. q. quelea in brood plumage on nest

Systematics
Order : Passerines (Passeriformes)
Subordination : Songbirds (passeri)
Family : Weaver birds (Ploceidae)
Subfamily : Ploceinae
Genre : Quelea
Type : Bloodbeak weaver
Scientific name
Quelea quelea
( Linnaeus , 1758)
Distribution area (green) of the bloodbeak weaver
Birds of the nominate form can be colored very variably. This specimen shows an extensive pink on the head and chest.
Bloodbeak weaver in simple dress. The sexes cannot be distinguished outside of the breeding season.
The bloodbeak weaver can form huge swarms.
Since bloodbeak weavers can cause massive crop damage in places, the species is sometimes vehemently fought.
In the midday heat, bloodbeak weavers often gather at mass resting places.

The blood- billed weaver ( Quelea quelea ) is a songbird species from the weaver bird family (Ploceidae). He settled Africa south of the Sahara and is one of the most common bird species on earth. After the breeding season, when the population with many of this year's birds reaches an annual maximum, the total population is estimated at 1.5 billion specimens, making the species the most common wild bird at all. It occurs regionally in huge swarms that can cause significant crop damage and are therefore sometimes fought vehemently. The huge breeding colonies can cover up to 110  hectares .

description

The blood-billed weaver is a small, short-tailed weaver bird species with a powerful beak, which, with a body length of 12 cm, is roughly comparable in size to a goldfinch . It weighs between 15 and 26 g.

Males in breeding plumage have a bright red beak. The iris is brown and the eye is surrounded by a narrow, red orbital ring. The head drawing is very variable in the nominate form ( Q. q. Quelea ). Usually the face area shows a black mask that extends over the forehead, reins, cheeks, ear covers, chin and throat. But it can also be dark pink to purple or creamy white and the extent is often very different. The rest of the head is usually straw-colored or dark pink. In the latter case, the pink color can extend to the abdomen. Otherwise the upper breast is usually straw-colored; lower chest and flanks are light brown. The flanks are also dashed dark. Belly and under tail-covers are white. The top is light brown and strongly irregularly striped by dark feathers. On the other hand, the stripes on the rump are finer. The upper wing is brown with yellowish seams on the wings. The control springs are brown. Legs and feet are orange.

The beak of the male in the plain dress is red to pink. The face mask is missing. The forehead and part of the head are gray-brown with dark dashes, the chin and throat are white. The chest is yellowish brown. The rest of the plumage corresponds to the brood dress. Legs and feet are flesh-colored.

The female resembles the male in the plain dress. Outside the breeding season it has a red beak and eye ring, while both are yellow during the breeding season.

Birds in their youthful dress can be recognized by their horn-brown beak and dull brown eye ring. The head is simply gray, the cheeks whitish. Wings and upper wing-coverts have yellowish-brown hems.

Distribution and geographic variation

With the exception of the rainforest belt , the Horn of Africa and some deserts and coastal regions , the bloodbeak weaver is common in almost all of sub-Saharan Africa.

Three subspecies are recognized, which differ mainly in the breeding dress of the males. The face mask from Q. q. aethiopica lacks the black forehead, the underside a yellowish-brown tint. Q. q. Like the nominate form, lathamii has a black forehead. The underside, however, is white.

habitat

The bloodbeak weaver is particularly common in semi-desert habitats. These include dry and thorn bush savannahs or, in many places, the cultural landscape . The species is rarely found in wetlands or pure dry areas . It is absent in forested regions. It generally inhabits the flat and hill country. The altitude distribution in East Africa ranges mainly from 500 to 1500 m, more rarely up to 3000 m. In the south, the bloodbill weaver can usually be found below 1000 m.

nutrition

The diet of the bloodbeak weaver consists mainly of seeds from wild grasses and cereals . In addition, insects are occasionally added.

Preference is given to eating seeds 1 × 2 mm in size, which are picked up on the plant or lying on the ground. The composition of the food spectrum can vary depending on the season and availability, so that cereals grown at certain times of the year become important as a source of food and the species then sometimes causes massive crop damage. In Kenya, for example, 80% of the seeds from wild grasses were eaten in October, but from February to April millet was more prominent with 40%.

The food spectrum in wild grasses consists of Dactyloctenium aegyptium , echinochloa as Echinochloa colonum and Echinochloa pyramidalis , Ischaemum brachyantherum , wild rice as Oryza bartii , Panicum as Panicum laevigatum , Setaria , Lampenputzer grasses , Schoenfeldia gracilis and species of the genera Paspalum and Urochloa .

The species causes crop damage in wheat , sorghum , millet , oats , buckwheat and rice . Crushed corn at cattle feed stations is also eaten.

Insects usually make up less than 10% of the food, but it can be between 35 and 50% in nestling food. Beetles , caterpillars and butterflies , grasshoppers , bed bugs , ants , " harvest determinants " (Hodotermitidae) and dragonflies are eaten or fed . Other arthropods such as spiders are also captured. Females eat parts of snail shells and eggshells as well as minerals to supply calcium before laying eggs.

Larger flocks look for food on the ground in “rolling motion”, with clouds of birds regularly flying over the front ones. Field research suggests that at mass resting places there is individual communication about the location of food sources, which later enables coordinated movement of the swarms. The species regularly visits drinking water points. In the midday heat, mass resting places often form in trees and bushes.

Reproduction

The bloodbeak weaver breeds in large colonies that can contain millions of nests. Up to 6000 can stand in a tree. Small colonies of less than ten breeding pairs also occasionally occur. The breeding business takes place very synchronously within the colonies, so that it is sometimes completed within 40 days and the colonies are completely cleared again. The breeding season varies according to geographic location and seems to correlate with greater rainfall , after which there is enough food and nesting material. In some regions, such as Kenya, there are two breeding cycles.

The bloodbeak weaver generally has a monogamous brood marriage, but birds have also been observed to nest in different places. This suggests that successive polygyny also occurs. Males defend the immediate nest area against rivals by singing and fluttering attack flights.

The nest is a small, spherical burrow made of grass that the male builds within two to three days. The side entrance is protected by a small rain canopy made of fresh blades of grass. The nest is generally one to six meters high in thorny trees. In most cases it doesn't hang very high at about two meters. Sometimes it is also in the reed beds or in sugar cane .

The clutch usually consists of three, rarely one to five eggs, which are about 18 x 13 mm in size on average. They are greenish or bluish and rarely have dark speckles. The egg-laying often begins when the nest is not quite ready. The breeding season is ten to twelve days. The nestlings fly out after ten to eleven days and are looked after by both parents. After flying out, they sit in the surrounding branches and are independent after 21 days.

In Nigeria, 87% of the nests flew young, in Senegal and Chad the average breeding success was two young per nest. Breeding colonies usually attract many predators , from large species of locusts such as Acanthoplus discoidalis or reptiles , through herons , storks , ibises and birds of prey to lions and leopards . Sometimes colonies are completely destroyed, such as a colony with 3000 nests of cattle egrets in South Africa . Most of the time, however, the damage is much lower and was around 15% in two colonies in the Kruger National Park .

Existence and control

The bloodbeak weaver is one of the most common bird species in the world. The total population after the breeding season is estimated at 1.5 billion specimens. The population in Kruger National Park is estimated at 33 million, that in neighboring Mozambique at 20 million. In Cameroon and Chad, up to 55 million were estimated by airborne surveys. A colony in northeast Nigeria comprised 110 hectares and probably 31 million nests.

During the dry season, large flocks made up of millions of birds form. Sometimes there are mixed flocks with other weaver birds or species such as the brown-backed gold sparrow .

Since the swarms invade grain-growing areas and can cause great damage there, they are massively fought in many places. Explosives, gasoline explosions and chemicals were or are being used. The latter includes above all the organophosphate fenthion , which (named after the scientific and English name Quelea ) is sold under the brand name Queletox®. It is a contact poison that is particularly fatal to insects and birds and is sprayed by plane over the mass sleeping or resting places of the species. The collateral damage is considerable, as the poison also affects other birds and insects and is also not harmless to humans, livestock and water. If the dead weaver birds are eaten, the scavengers or predators also die. This can also be a threat to European migratory birds such as the white stork .

Although in South Africa, for example, up to 21 million birds are destroyed in a month, and sometimes around 180 million in a year, these actions remain unsuccessful. They only replace the already occurring natural mortality. Newer defense methods therefore exist, for example, in planting new cereal varieties or in changed cultivation times.

Individual evidence

Unless otherwise stated, the information in the article is based on the source given under "Literature" (HBW alive).

  1. ↑ a b Holger Schulz: White stork migration - ecology, endangerment and protection of the white stork in Africa and the Middle East , WWF environmental research, publisher josef margraf, Weikersheim 1988, ISBN 3-8236-1141-0 , p. 32
  2. ↑ James O. Keith, Richard L. Bruggers, Bruce A. Kimball, John G. Ngondi, Clive CH Elliott: Environmental effects on wetlands of queletox® applied to ploceid roosts in Kenya , Environmental Toxicology and Chemistry , Volume 13, Issue 2, 1994, pp. 333-341, doi : 10.1002 / etc.5620130218
  3. ↑ RW Palmer: Detrimental Effects of Fenthion (Queletox® UL), used to control Red Billed Quelea (Quelea quelea), on Rheophilic Benthic Macroinvertebrates in the Orange River , Southern African Journal of Aquatic Sciences , Volume 20, Issue 1-2, 1994 , Pp. 33-37 doi : 10.1080 / 10183469.1994.9631348

literature

  • Adrian Craig: Red-billed Quelea (Quelea quelea) (2010), in: J. del Hoyo, A. Elliott, J. Sargatal, AD Christie, E. de Juana (eds.): Handbook of the Birds of the World Alive , Lynx Edicions, Barcelona 2014

Web links

Commons : Bloodbeak Weavers  - Collection of images, videos and audio files