Bustards

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Bustards
The great bustard is one of two European species, here photographed in the Hungarian Hortobágyi National Park

The great bustard is one of two European species, here photographed in the Hungarian Hortobágyi National Park

Systematics
Sub-stem : Vertebrates (vertebrata)
Class : Birds (aves)
Order : Otidiformes
Family : Bustards
Scientific name of the  order
Otidiformes
Wagler , 1830
Scientific name of the  family
Otididae
Rafinesque , 1815

The bustards (Otididae), also known as trap geese , are a family of small to very large, ground-living, but airworthy birds. Most species live in Africa, two species also occur in Europe.

description

Bustards are small to very large, airworthy birds. The trunk is strong, the neck and legs are long, and the tail and beak are short. The largest species are 1 m high and weigh 10 kg, in exceptional cases even 19 kg, making them the heaviest birds in the world capable of flying. The females are considerably lighter and smaller in the large species; they are only two-thirds the height and one-third the weight of the average male. In the case of smaller species, on the other hand, there are no significant differences in size. The smallest species is the flag bust with a length of 46 cm and a weight of 450 g.

The giant bustard is the heaviest bird in the world capable of flying

The plumage is predominantly a little noticeable brown or gray with white and black markings. The number of control feathers is between 16 and 20. All species show a more or less clear sexual dimorphism in color. The males usually have lighter plumage colors and often decorative feathers on the crown, neck, cheeks, throat or neck. In the roosters of a number of species the neck is thickened during the breeding season or is at least enlarged during courtship by pumping up part of the esophagus or additionally a throat pouch.

The legs are feathered down from the middle of the tibiotarsus . The animals have only three toes with wide claws hollowed out below, the rear toe is missing ( tridactyly ). Tridactyly means that bustards do not find support on trees and only live on the ground. Mostly bustards walk at a slow pace. Fast running is hardly possible due to the relatively small feet.

The large wings are rarely used - the larger species in particular often spend several weeks on the ground without even getting up in the air. Bustards, however, are persistent fliers - some species make seasonal migrations with considerable distances. The small bustard species have a fast, duck-like flight, while the large bustard flies with slower wingbeats.

The species of the family do not have a rump gland , but have pink powder down ; the bases and flags of the contour feathers are also pink and give off powder. A penis is rudimentary. The caecum is very long and is used to break down cellulose .

distribution and habitat

Rüppelltrappen ( Eupodotis rueppellii )

The main range of the family is Africa with 16 of 27 species, other species live in Europe and Asia , one in Australia . There are two species in Europe, the great bustard and the little bustard . As predominantly heat-loving ground birds, bustards live in open landscapes with rich ground vegetation such as steppes, semi-deserts and cultural steppes.

In four species, at least partial populations are migratory birds. This applies to the Palearctic species (great bustard, little bustard, collar bustard), which mainly migrate from the Russian cold steppes to subtropical regions. The fourth species is the bustard flag, which breeds in Gujarat and overwinters in southern India.

In the Austrian Burgenland there has been a bustard protection area in the Pama / Parndorfer Platte area since 1995 . The great bustard found here was threatened with extinction and in 2002 only had about 60 animals. Due to extensive protective measures, such as the partial laying of power lines underground or flagging the high-voltage lines, the population rose to around 250 great bustards by 2013 and their habitat expanded further towards Kittsee , which was the last to join the bustard protection region.

Way of life

activity

Bustards are diurnal birds that are most active in the morning and evening. At night they rest, mostly standing, but occasionally with their stomach on the floor.

Many bustard species live at least outside of the breeding season in loose associations, which usually only include a few individuals. There is little social interaction in these associations, the birds keep separating and find themselves in new combinations. In all species except the little bustard there are pure male and pure female associations. Females are generally more solitary than males. Bustard associations often join herd-living mammals. The group provides protection from predators. A specialty are the associations of the little bustard, which can comprise several thousand animals in the steppes of southern Russia.

The enemies of small bustard species include large birds of prey (in Africa mainly combat eagles , coffee eagles , predatory eagles ), baboons , mongooses and monitor lizards . The great bustards naturally have fewer enemies. In the event of a threat, bustards adopt a posture in which they stretch their bodies out, spread their wings and fold out their tails like a fan.

nutrition

As omnivores, bustards consume plant and animal food. There are also big differences within the species depending on habitat and season.

Vegetable food is mainly made up of green parts of plants such as fresh leaves, as well as flowers, fruits and tubers. The latter are dug up with the beak.

Invertebrates make up the majority of animal food. These are grasshoppers, beetles, termites, ants, caterpillars, spiders, millipedes, scorpions and snails. The small bustards eat exceptionally, while the large ones regularly eat small vertebrates such as snakes, lizards, eggs, young birds and rodents. Even carrion is not spurned.

Bustards get their fluid needs mainly from food and can do without water for a long time. But if there is water, they also drink.

Reproduction

White-winged bustard

The majority of the species have a polygynous reproductive system: a male mates with several females and does not help with breeding and rearing young ones. The exception to this rule are the small African bustards of the genus Eupodotis , which are seasonally monogamous and for which a couple takes on the rearing of the young together, often supported by a male offspring from the previous year.

The breeding season begins in the temperate zone in spring, in the subtropical and tropical regions it depends on the respective rainy seasons; for example, it is in the Sahel region in July. Rainy periods guarantee sufficient availability of vegetable food and an abundance of insects so that they are suitable for raising young.

The courtship is very different from species to species. The great bustard courtship has become known, in which several males gather in a lek and court the females standing around it. The throat pouch is inflated like a balloon, the beard feathers are erected, the tail is spread out like a fan and the wings are left hanging. The Great Bustard thus presents all the shining parts of the plumage that usually remain hidden. A lek system can also be found in other species, but usually a male maintains a territory in which he does not tolerate other males and court alone. In large species, courtship takes place entirely on the ground. Some smaller species court in flight. Here the males rise to a height of around 20 m and sink in gliding flights; in between they stand on elevated positions, for example termite mounds .

Apart from the Eupodotis species, after copulation the females leave the males, who have nothing to do with the further breeding business. You choose a nesting place that is always on the ground - often under the protection of nearby shrubs or rocks, but sometimes completely open. A nest is not built, at most the vegetation is scraped aside a little.

Most species lay one or two eggs. In the European species, the great bustard and the little bustard, the clutch size is two to three. The bustard flag has the largest clutch with three to five eggs. The eggs are gray or olive colored and irregularly spotted. The brood lasts 20 to 25 days. Then the young hatch and are ready to walk just a few hours later. As soon as all are qualified, the female and her young leave the nest. The young are quickly able to eat independently.

Four to five weeks after hatching, the young are able to fly, but they often do not use this ability for many more weeks. It takes a few months for them to be independent from their parents. In the young of the genus Eupodotis , male young often stay with their parents for more than a year and help with the rearing of the subsequent brood. Female bustards become sexually mature at around two years of age, while males do not become sexually mature until they are six.

Systematics

In the past bustards were assigned to ratites , chickens and, most recently, crane birds . The composition of the crane birds was controversial and the bustards and some of the bird families originally classified there are not closely related to the others. In more recent systematics, they are therefore placed in their own order, the otidiformes. According to Jarvis and colleagues, their closest relatives are the turacos (Musophagiformes) and the cuckoo birds (Cuculiformes).

The molecular clock suggests that the last common ancestor of the modern bustards may have lived in the Miocene . The bustard family probably originated in Africa, where the greatest diversity of species still exists today.

The internal system of the family has long been the subject of controversy, the following list of 12 genera and 27 species follows the IOC World Bird List.

Oustalettrappe
Black-eared bustard
Senegal bustard

People and bustards

Ludwig bustard

Prehistoric cave drawings , on which great bustards can already be seen , show that people have long been familiar with bustards . Over the past few centuries, the two European species have benefited from clear-cutting forests and the creation of cultivated landscapes. Both species were considered pests because they ate the crops that were grown. In the 18th and 19th centuries, the great bustard was a very common bird in all of Central Europe that was even viewed as a nuisance. The dramatic decrease that followed is mainly due to the use of pesticides , industrialization of agriculture and hunting. By 1990 the number of Great Bustards in Germany had dropped to 50 animals; Today, however, this number has increased again thanks to intensive protective efforts. Across Europe, however, stocks are still falling; The great bustard is now completely extinct in Switzerland, Poland, Sweden and Great Britain.

In earlier times bustards were eaten in Europe just like their eggs. Today bustard meat is only consumed in a few parts of the world, for example in Chad . Little bustards are still considered a pest in some areas of Russia. On the other hand, many species are very popular in Africa, as they follow swarms of migratory locusts and devour them.

Bustard hunting with falcons is a tradition on the Arabian Peninsula . The bustard was almost exterminated by this custom. Tourists from Arab countries now go bustard hunting in Africa and Asia and thus exert great pressure on the populations.

The IUCN currently classifies two species as endangered (great bustard, collar bustard), two as critically endangered (Hindu bustard, bearded bustard) and one as critically endangered (flag bustard).

Sources and further information

Sources cited

Most of the information in this article is taken from the source given under literature; the following sources are also cited:

  1. ↑ www.grosstrappe.at: orf.at: Trappenschutz - Projekt greift (screenshot) (PDF), October 17, 2007 (accessed on February 23, 2015)
  2. ↑ mein district.at: Bustard protection predecessor becomes successor , September 2, 2014 (accessed on February 23, 2015)
  3. ↑ Hackett et al .: A Phylogenomic Study of Birds Reveals Their Evolutionary History . Science 27 June 2008: Vol. 320. no. 5884, pp. 1763–1768 doi: 10.1126 / science.1157704
  4. ↑ a b Erich D. Jarvis et al .: Whole-genome analyzes resolve early branches in the tree of life of modern birds. December 12, 2014, science • Volume 346, edition 6215, doi: 10.1126 / science.1253451
  5. ↑ a b IOC World Bird List: Bustards, mesites, Kagu, seriemas, flufftails & finfoots, accessed June 26, 2015
  6. ↑ Christian Pitraa & al .: Phylogenetic Relationships and Ancestral Areas of the Bustards (Gruiformes: Otididae), Inferred from Mitochondrial DNA and Nuclear Intron Sequences . In: Molecular Phylogenetics and Evolution 2002, Vol. 23, No. 1, pp. 63-74
  7. ↑ AE Brehm, Das Leben der Vögel , 2nd edition, Glogau 1867, p. 556 ff.
  8. ↑ Nabu: Great bustard populations have stabilized  ( page can no longer be accessed , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. , accessed April 29, 2009.@1@ 2Template: Dead Link / www.nabu.de  
  9. ^ Otis tarda in the IUCN Red List of Threatened Species . Retrieved April 29, 2009.
  10. ^ Search for "Otididae" in the IUCN Red List of Threatened Species . Retrieved November 16, 2011.

literature

  • Josep del Hoyo et al .: Handbook of the Birds of the World. Volume 3: Hoatzins to Auks. Lynx Edicions, 1996, ISBN 84-87334-20-2 .
  • Urs N. Glutz von Blotzheim, Kurt M. Bauer: Handbook of the birds of Central Europe, Volume 5, Galliformes - Gruiformes. Aula, Wiesbaden, 2nd edition 1994: pp. 616–617, ISBN 3-923527-00-4

Web links

Commons : Bustards  - collection of images, videos and audio files