Elven tern
| Elven tern | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Gygis microrhyncha | ||||||||||||
| Saunders , 1876 |
The elven tern ( Gygis microrhyncha ) is a species of bird from the order of the plover-like (Charadriiformes). It is often considered a subspecies of the fairy tern ( Gygis alba ), but some authors as well as BirdLife International and the IUCN support the classification as an independent species.
features
The elven tern reaches a size of 23 cm, a wing span of 76 to 80 cm and a weight of 77 to 122 g. The plumage is generally white with no seasonal or gender-specific variations. It differs from the fairy tern in its smaller size, a flatter tail notch, an intense black eye ring and a whitish hand-swing shaft. The eyes appear large due to the intense dark coloring and the ring. In flight, wings and tail often appear shimmering through. The black beak occasionally has a tiny blue base. It is sharply pointed and the distal part of the lower mandible is slightly curved upwards. Legs and feet are slate blue with yellowish to white webbed feet. The juvenile birds are similar to the adult birds, apart from the body and wing feathers, which have different brown fringes. The base of the beak is black and there may be a black spot behind the eyes.
Vocalizations
Differences to the fairy tern are not known. There is hardly any vocal communication between chicks and adult birds. Small chicks occasionally emit a soft squeak when the parents return to the nest with food, but the adult birds do not respond to it vocally.
distribution and habitat
The elven tern breeds in the Marquesas , especially from Eiao to Fatu Hiva , and apparently also on the Phoenix Islands and the Line Islands . In addition, birds in Kiribati that were previously thought to be fairy terns could be elven terns. It is a migratory bird that reaches the Hawaiian Islands on its migrations .
The elven tern inhabits coral islets, usually with vegetation. The nests are built on trees, bushes and on rocky slopes or cliffs. It is not a deep sea bird, but usually goes in search of food above the waters near its breeding islands.
Reproductive behavior
There is little research into reproductive behavior, although in many ways it is similar to that of the fairy tern. The breeding season on Hatu Iti in the Marquesas includes both March and September. On Hatutu in the same archipelago, nesting birds were observed in June and August, but not in November, while eggs were found in July and young birds in March on the Sorol Atoll in the Western Carolines . On the Sapwuahfik -Atoll (Ngatik) the terns nest in coconut palms and screw trees . Further information on reproductive behavior is not known. Hybrids can arise between the elven tern and the fairy tern .
status
The elven tern is classified by the IUCN as "not endangered" ( least concern ). More than 1000 pairs brooded on Hatutu in the Marquesas in 2010. Overall, the population is considered stable. However, there are indications of a decline in Pohnpei in the East Carolina between the early 1980s and the mid-1990s, where two to six individuals per hour were counted at altitudes above 200 m and one to two individuals at altitudes below 200 m. In the latter case, rats or other introduced predators are likely to have been the main reason for the decline. In the past the elven tern was also found on Mangaia in the Cook Islands , but here it disappeared some time after the colonization. A former presence on Easter Island is based on false information. Further studies on the ecology, population and protection of this species are urgently needed.
literature
- del Hoyo, J., Collar, N. & Kirwan, GM (1996). Little White Tern (Gygis microrhyncha). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, DA & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (Retrieved from HBW Alive Database on July 4, 2015).
- del Hoyo, J .; Collar, NJ; Christie, DA; Elliott, A .; Fishpool, LDC 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
- Pratt, HD, Bruner, PL & Berrett, DG (1987): A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton Univ. Press, Princeton, New Jersey.
Web links
- Gygis microrhyncha inthe IUCN Red List of Threatened Species 2014.3. Listed by: BirdLife International, 2014. Retrieved July 4, 2015.
- BirdLife International: Species Factsheet - Little White Tern ( Gygis microrhyncha ) . Retrieved July 4, 2015.
Individual evidence
- ↑ del Hoyo, J .; Collar, NJ; Christie, DA; Elliott, A .; Fishpool, LDC 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
- ↑ Pratt, HD, Bruner, PL & Berrett, DG (1987): A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton Univ. Press, Princeton, New Jersey.
- ↑ Olson, SL (2005): First occurrence of Gygis microrhyncha in the Hawaiian Islands. Bull. Brit. Orn. Club 125 (2): 155-157.
- ↑ Commission Internationale pour les noms français des oiseaux, 1993
- ^ The Sibley & Monroe World List of Bird Names , 1996