Black-headed divers

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Black-headed divers
Least grebe.jpg

Black- headed Grebe ( Tachybaptus dominicus )

Systematics
Class : Birds (aves)
Order : Grebes (Podicipediformes)
Family : Grebes (Podicipedidae)
Genre : Tachybaptus
Type : Black-headed divers
Scientific name
Tachybaptus dominicus
( Linnaeus , 1766)

The black-headed diver ( Tachybaptus dominicus ) is the smallest species of the grebe family . The species occurs in Baja California , Central America , the Caribbean and South America . There are four (sometimes five) subspecies, which differ from one another mainly in their size. The population of the species is stable and is classified by the IUCN as not endangered ( least concern ).

Appearance

Black-headed divers reach a length of 21 to 27 centimeters and a weight of 112 to 180 grams, depending on the subspecies. The plumage of adults is brownish to soot-colored, the beak dark and the eyes yellow. As with all rag divers, the legs of the black-headed divers are set relatively far back on the body, which makes them excellent swimmers, but makes movement on land difficult.

The young of the black-headed divers have white stripes on their heads. Your eyes are brown and get lighter over time. The neck is white.

distribution and habitat

Distribution areas of the black-headed divers
(The black lines delimit the areas of the four generally recognized subspecies.)

The distribution of the five subspecies of the black-headed divers extends over Baja California, Central America, the Caribbean and South America:

There are five known subspecies:

  • T. d. brachypterus ( Chapman , 1899) - This subspecies is distributed from southern Texas through western central Mexico to Panama.
  • T. d. bangsi ( van Rossem & Hachisuka , 1937) - This subspecies occurs in western Mexico .
  • T. d. dominicus ( Linnaeus , 1766) - The nominate form occurs in the Greater Antilles .
  • T. d. brachyrhynchus ( Chapman , 1899) - This subspecies is common in northern South America to northern Argentina .
  • T. d. eisenmanni Storer & Getty , 1985 - This subspecies occurs in western Ecuador .

Black-headed divers use a variety of different wetlands. These range from smaller ponds to larger lakes to rivers, marshes and mangrove swamps. But even irrigation ditches and artificial lakes in agriculture are used. Black-headed divers especially prefer locations with dense vegetation.

All subspecies of the black-headed divers are considered resident birds . A local spread occurs mainly after the rainy season , when the birds colonize newly formed wetlands. The animals then move on as soon as a wetland dries up in summer.

Food and subsistence

Black-headed divers feed mainly on insects and other invertebrates. The food spectrum ranges from water beetles , water bugs , spiders and dragonflies to small fish and crustaceans . Most prey animals are taken in diving, whereby the diving process can be preceded by a search in which the black-headed diver glides over the surface of the water with its head submerged. In addition, prey is also picked up on the surface of the water. Black-headed divers also eat food floating on the water and sometimes hunt insects that are in flight.

Reproduction

The breeding of the black-headed grebe mainly takes place between April and August, with nests being found in Texas throughout the year that contained eggs even in January and December. In the tropics, the animals breed mainly during the rainy season.

The clutch consists of 4–6 eggs from which the young hatch after an incubation period of around 21 days. Often 2–3 broods are raised per year.

supporting documents

Individual evidence

  1. ↑ BirdLife Factsheet , accessed February 15, 2014.
  2. ^ Ogilvie / Rose, Grebes of the world , p. 92.
  3. ^ IOC World Bird List Grebes, flamingos & tropicbirds
  4. ↑ Frank Michler Chapman, p. 256.
  5. ^ Adriaan Joseph van Rossem et al. a., p. 323.
  6. ↑ Carl von Linné, p. 223.
  7. ↑ Frank Michler Chapman, p. 255.
  8. ↑ Robert Winthrop Storer et al. a., p. 38.
  9. ↑ a b c For this and the following cf. Ogilvie / Rose, Grebes of the world , pp. 32-34.
  10. ↑ Ogilvie / Rose, Grebes of the world , p. 93.

literature

  • Malcolm Alexander Ogilvie, Chris Rose : Grebes of the world . Uxbridge 2003, ISBN 1-872842-03-8 , pp. 32-34 (English).
  • Carl von Linné: Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, Cum Characteribus, Differentiis, Synonymis, Locis . 13th edition. tape 1 . Typis Ioannis Thomae, Vindobona 1766 ( online [accessed March 21, 2015]).
  • Robert Winthrop Storer, Thomas Getty in Paul Anthony Buckley, Mercedes Suarez Foster, Eugene Siller Morton, Robert Sterling Ridgely, Francine G. Buckley: Neotropical Ornithology (Ornithological Monographs No. 36) - Geographic variation in the least grebe Tachybaptus dominicus . University of California Press, Berkeley, California 1985, ISBN 0-943610-44-3 , pp. 31-39 , doi : 10.2307 / 40168276 .
  • Adriaan Joseph van Rossem, Masauyi Hachisuka: A further report on birds from Sonora, Mexico, with descriptions of two new races . In: Transactions of the San Diego Society of Natural History . tape 8 , no. 23 , 1937, pp. 323–334 ( online [accessed March 21, 2015]).
  • Frank Michler Chapman : Description of two new subspecies of Colymbus dominicus Linn. In: Bulletin of the American Museum of Natural History . tape 12 , no. 19 , 1899, pp. 255–256 (English, online [PDF; 197 kB ; accessed on February 12, 2016]).

Web links

Commons : Tachybaptus dominicus  - collection of images, videos and audio files