Brown Noddy Anous stolidus 白頂玄鷗
Category I. Accidental.
IDENTIFICATION
Jul. 2021, Kinni Ho.
40-45 cm. Tern-like seabird, slightly larger than Sterna terns in HK, with wedge-shaped tail (pointed when closed). All dark plumage apart from greyish-white forehead and crown and slightly darker tail and tips to wing. Pale crown merges into brown on the nape and lower part of the face. Black lores usually have curved edges and contrast strongly with pale forehead and white orbital ring.
Juveniles are paler and duller with pale fringes to upperpart feathers in fresh plumage and a largely brown crown.
Jul. 2021, KWOK Tsz Ki.
Distinguished from Black Noddy in being slightly paler and having a thicker and stronger bill, and wings that fall short of the tail at rest.
Immature birds are slightly paler, sometimes with light streaks on wings, and compared to Black Noddy there is a more contrasting white border to the crown above the eye
VOCALISATIONS
The call is a rather deep and throaty rattle that falls in pitch.
DISTRIBUTION & HABITAT PREFERENCE
Records have occurred in southern waters and the outer part of Tolo Harbour, one during the passage of tropical storm.
OCCURRENCE
2006: one off Po Toi on 17 May.
2020: one on Castle Rock, Po Toi during 2-3 August in the wake of a tropical storm.
2021: one off Wong Mau Chau, near Tap Mun, Sai Kung on 20 June and presumably the same during 11-12 July.
BEHAVIOUR, FORAGING & DIET
Takes food from water surface.
RANGE & SYSTEMATICS
Four subspecies are recognised, of which the birds occurring in HK are presumed to be A. s. pileatus, which breeds from the Red Sea east through the Indian and Pacific Oceans as far as Hawaii and Easter Island. The remaining three subspecies occur in the eastern Pacific and tropical Atlantic.
Breeds on tropical and subtropical islands and islets in Atlantic, Pacific and Indian Oceans between 30oN and 30oS (Chardine et al. 2020). In China there are occasional records from southeast coastal areas, including Hainan, and it is a summer visitor to Taiwan (Liu and Chen 2020).
CONSERVATION STATUS
IUCN: Least Concern. Population trend stable.
Chardine, J. W., R. D. Morris, M. Gochfeld, J. Burger, G. M. Kirwan, and E. F. J. Garcia (2020). Brown Noddy (Anous stolidus), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.brnnod.01
Liu, Y. and Y. H. Chen (eds) (2020). The CNG Field Guide to the Birds of China (in Chinese). Hunan Science and Technology Publication House, Changsha.
