Christmas Island Boobook
Ninox natalis
Small, distinctive boobook with extensive chestnut-brown barring. Favors surviving primary rainforest, but can sometimes be found in secondary growth; can be found on roadsides through suitable habitat when hunting. The only resident owl on the island; the migratory Northern Boobook is a winter visitor to the island, and is significantly larger and much darker overall, with an all-brown head and brown-striped white underparts. Present species gives an odd, distorted-sounding “qwr-qwerk.” Begging birds give a shrill trill. Unfortunately, like many other Christmas Island species, has suffered declines due to the introduced yellow crazy ant, which has caused the owl to disappear from parts of its range.
识别特征
The Christmas Island hawk-owl is a small, rufous-brown hawk-owl with a barred breast, dark chestnut facial mask, whitish brow, lores and throat, yellow eyes, legs and feet. It is approximately 26–29 cm in length and 130-190 grams in weight with the female slightly larger than the male.<p>Its double-noted hoot, boo-book, has a clucking quality with the second note usually lower in pitch. The begging call of juveniles is a high-pitched trill.<p>Vocalisations are similar to those described for the Australian boobook (Ninox boobook) and include individual variation in advertisement calls. This may be useful in estimating owl densities as radio-tracking can be impractical in some terrains.
分类信息
- 学名
- Ninox natalis
- 命名信息
- Lister, 1889
- 目
- Strigiformes
- 科
- Strigidae
- 属
- Ninox
分布与栖息地
Ninox natalis is endemic to Christmas Island, a small Australian territory of about 135 square km situated in the Indian Ocean approximately 360 km (220 mi) south of Java.<p>The flora and fauna of the island face on-going threats from both human activity and introduced species of plants and animals. In addition to these threats, N. natalis is restricted to a small range on this small island and is consequently listed as vulnerable by the IUCN.<p>Phosphate mining has continued for over a century and more recently Australian Immigration Detention Facilities have been established increasing the impact from human habitation. However, the Australian National Parks and Wildlife Service manage 64% of the island as a national park. Its natural habitats are subtropical or tropical moist lowland forest and subtropical or tropical moist shrubland.<p>Ninox natalis occupies essentially exclusive territories and is widespread on the island utilizing both primary and disturbed habitats. However, in areas of regrowth significantly fewer birds have been detected. In 1995 there were approximately 560 breeding pairs, but by 2004 the population was estimated to be down to 1000 birds. A more recent estimate in 2011 suggests that the population may, however, be significantly lower than that.<p>Preferred roost sites are sheltered and concealed positions from which they can easily escape such as in the bottom third of the canopy of trees with deep crowns and mid-level understory but with fewer low understory trees.<p>Nests have been found in tree hollows predominantly in the canopies of Planchonella nitida, Hernandia ovigera and Syzygium nervosum.
- 迁徙
- Resident species
保护状况
- 种群趋势
- stable
照片
分布
其他鸟类
Pacific Imperial-Pigeon
Ducula pacifica
A large pigeon with a mostly gray body, green wings, and a distinctive and diagnostic black fleshy knob above the bill. Found mostly in inland forest up to around 1000 meters of elevation. Juvenile resembles Island Imperial-Pigeon, but is smaller and overall darker, especially on the wings. Adult is separated from Island Imperial-Pigeon by its black bill knob. Often heard giving an extended, rapidly bubbling “crrrroooooo” call.
Blue-banded Pitta
Erythropitta arquata
Unique-looking pitta of hill and submontane forests. Note bright red underparts, dull tan-orange face, dull blue-green back, and glittering silver-blue “necklace” and secondaries (similarly-colored line trailing down from behind the eye can be visible if seen well). Favors patches of forest with some disturbance, especially bamboo groves and fallen trees. Shy and elusive. Gives a whistle with a clipped ending; higher and more “fluty” than that of Black-crowned Pitta, and lacks the rising quality of that species’ and Garnet Pitta’s whistles.
Greater Spotted Eagle
Clanga clanga
Adults are large and quite uniform dark brown eagles with very broad wings and short tails. Single white "comma" mark at the wrist of the underwing. Similar to the Lesser Spotted Eagle, which is smaller, paler, and more contrasting. Juveniles are more boldly patterned with numerous prominent dirty white spots on the back and upper wings. More tied to forests than Lesser Spotted Eagle, but still near rivers and bogs. Frequents humanmade habitats more often in winter, such as lakes, rubbish dumps, and reservoirs.
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