Long-beaked gingones
| Long-beaked gingones | ||||||||||||
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Long-billed gingerbread ( Gerygone albofrontata ) |
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| Scientific name | ||||||||||||
| Gerygone albofrontata | ||||||||||||
| GR Gray , 1844 |
The long-beaked gingerbread ( Gerygone albofrontata ) is a songbird species from the family of the South Sea warblers (Acanthizidae). It is endemic to the chatham islands . The Maori Ygons ( Gerygone igata ) live on mainland New Zealand as their closest relative . The long-beaked gingerbread is larger and shows a clear sexual dimorphism as well as a special plumage of the juvenile specimens. Both gerygone species were discovered and described by GR Gray in 1845. They are the only two members of the Australasian family of South Sea Warblers in the New Zealand area .
features
The head and back of the long-beaked gingerbread are olive brown. The underside is dirty white, the flanks and the lower tail pale yellow. The front of the head, eyebrows, throat and underside of the males are conspicuously white. The females lack these features, but they are darker on the underside and have yellow eyebrows, cheeks and throats. The adult animals have red eyes. Young animals are similar to the females in their fletching and also have brown eyes.
When fully grown, the animals are approx. 12 cm long; the males are somewhat plump than the females. They reach an average of 10 g and 8.5 g in weight.
The singing of the long-beaked gingerbread is tender and rich in verses. It is comparable to the singing of Maori Ygons, but is not as fully developed. A recurring cue is a phrase with 4 repeating tones that is repeated many times over the course of the chant. It is said that the Māori saw this melody as a sign of when it was time to plant.
distribution
The birds live in the forests of the Chatham Islands. They are mainly found in the south of the main island, but are also found on the surrounding islands, such as Pitt Island , Little Mangere Island , Star Keys and Rangatira . Habitat loss and introduced rats and cats are held responsible for not being found in the north of the main island.
Ecology and behavior
The birds feed on small insects. They are constantly out and about in the tree tops and bushes looking for food and looking for food on leaves and branches. Occasionally they also search fallen leaves. In contrast to the Maori Ygons, they do not catch insects in flight.
Occasionally there is brood parasitism by bronze cuckoos (Chrysococcyx lucidus). As soon as the cuckoo chick hatches, it throws all the other eggs out of the nest and can be raised by the foster parents.
- Breeding behavior
The long-beaked gingerbread creates individual nests and defends the surrounding territory against competitors. Conflicts are mostly carried out by the males, and prolonged chases occasionally occur but never serious fighting. The gerygons are monogamous and it has been observed that the breeding territories are defended for up to three years.
The breeding season shifts each year, but generally extends from September to January. The nest is, similar to the nest of the relatives in New Zealand, pear-shaped with a side entrance near the top. The location of the nests varies depending on the island. On the main island they hang open or in gaps in the vegetation, on the smaller islands they are more likely to be found in dense foliage. The nest is built by the female alone from grass, leaves, roots and moss, which are held together with cobwebs. The nest can be between 50 cm and 7.5 m above the ground and is lined with feathers and other soft material. It is attached to the top of a branch, but is often additionally attached to the back or sides. The male is also not involved in the breeding business, but does feed the young. The 3 to 7 eggs are laid every 2 days; they are dirty white with small reddish brown spots. They weigh 1.5 grams and are about 17 mm long and 12 mm wide. The incubation period is 19 days; the young spend another 15 to 19 days in the nest. The birds have a breeding success of 87%. This is significantly higher than the breeding success of the Maori Ygons.
Hazard and protection
The species is on the Red List of the IUCN classified as "least concern". The size of the total population is unknown, but it is believed that it is decreasing. Introduced rats and domestic cats, as well as habitat degradation, have caused the population to decline on Chatham Island .
Individual evidence
- ↑ a b c d e f Chatham Island warbler . New Zealand Birds Online. Retrieved March 2, 2015.
- ↑ a b c d e Te Ara: The Encyclopedia of New Zealand . Retrieved March 2, 2015.
- ↑ a b G. R Gray: Gerygone albofrontata . In: Zoology of the Voyage of HMS Erebus and Terror . 1844, p. 5. Retrieved March 3, 2015.
- ^ Song variation among Chatham Island Warblers . Retrieved March 4, 2015.
- ↑ Chatham Island fantail, Chatham Island tomtit and Chatham Island warbler recovery plan (PDF). Retrieved March 3, 2015.
- ↑ MD DENNISON, HA ROBERTSON, D. CROUCHLEY: Breeding of the Chatham Iceland warbler (Gerygone albofrontata) . In: Notornis . 31, No. 2, 1984. Retrieved March 3, 2015.
- ↑ Gerygone albofrontata in the Red List of Threatened Species of the IUCN 2016. Posted by: BirdLife International, 2016. Retrieved on January 25, 2017.
Web links
- Chatham Island fantail, Chatham Island tomtit and Chatham Island warbler recovery plan 2001–2011 (PDF) Department of Conservation, Wellington, New Zealand. 2001. Retrieved October 4, 2007.