IDENTIFICATION

VOCALISATIONS

The territorial call is a downslurred ‘whoo’ or ‘pyoo’. Although in very calm conditions it is audible at a distance of 500 metres (Lewthwaite and Yu 2007), at any distance it may sound soft or muffled. The following recordings illustrate the variation in this sound that may be encountered.

Based on the time between 337 territorial calls from 14 birds recorded at Pak Sha O, the mean interval between notes is 9.26 seconds (SD 2.26) with a range of 6.33 to 14.22 seconds. This is substantially lower than the 15-20 seconds noted for the species by Konig and Weick (2008).

Occasionally a short series of notes is given, though it is usually uttered only once in several hours.

During the breeding season, other vocalisations may also be heard from adults.

Young in the nest and, according to Holmes and Holmes (2010), those recently fledged utter distinctive loud hissing noises.

DISTRIBUTION & HABITAT PREFERENCE

Very widespread in the New Territories and fairly widespread on HK Island and Lantau, mainly below 300 metres asl but locally up to about 700 metres asl and increasing as a result of the spread and maturation of shrubland in recent years, with detections in over 80% of grid squares covered in the Nightbird Survey of 2020-2021. Elsewhere, occasionally reported from Kowloon, Lamma, Po Toi, Kat O, Crescent Island and Tap Mun. Highest densities are found in areas of closed-canopy mixed shrubland near permanent streams (Lewthwaite & Yu 2007). It also occurs at lower densities in forest and wooded thickets, especially fung shui woods, and very occasionally in mangroves and urban parks. Favoured sites are Shek Kong Catchwater, Lam Tsuen Valley, Tai Po Kau, the Brides Pool Road area, Yung Shue O, Pak Sha O and Tai Tam CP.

OCCURRENCE

Recorded in all months of the year with the distribution of sightings largely reflecting patterns of vocal activity throughout the year (Figure 1). Numbers detected are relatively low at the beginning of January but increase in the second half of January to peak during a 10-week period from mid-March to the end of May (40% of the total), after which they return to low levels from June to December, though with a slight increase apparent in October and November. The period of peak detections in March, April and May coincides with the breeding season, and the increase in October and November possibly coincides with post-breeding dispersal of juveniles, though this is not known for certain.

Most reports are of one or two bird and highest counts are all at shrubland sites, the highest being 13 at Tai Tam CP on 18 May 2021; seven at Tai Po Kau on 13 May 2001 is the highest count at a forest site.

A specimen from HK dated 22 April 1901 (Styan Collection, BMNH) is the first known record. The species was generally regarded as a common or locally common resident in the past (Vaughan and Jones 1913, Herklots 1939, Macfarlane & Macdonald 1966, Chalmers 1986, Carey et al. 2001).

BREEDING

There are over 30 breeding records of Collared Scops Owl dating back to the early 1900s (Jones 1908, Vaughan and Jones 1913) and on the HKBWS database from 1959 to the present day. Twelve clutches of 3-5 eggs have been found in the period 15 March to mid-May, though since 1959 none later than 10 April. Fledged young have been seen in the immediate vicinity of a known or suspected nest site, often accompanied by adults, from 9 April to 9 July.

Most nest-sites found since the 1990s are tree-holes, tree-stumps and artificial nest-boxes attached to trees. The opening to the nest is sometimes less than 2 metres above the ground, including one from which three young fledged which was only five metres from a frequently-used classroom on the CUHK campus. Previously, Oriental Magpie nests were frequently used, with egg-clutches of this owl found on seven occasions between the early 1900s and 1975, including in one nest built on a pylon. Other nest-sites recorded are a ledge approximately 20 metres high under the eaves of a residential building, a hole in a steep bank of disintegrated sandstone, a weep-hole in a concrete retaining wall along a water catchment and a tree-root on the ground. A nest in a tree at Pak Sha O was within 20 metres of an active Brown Fish Owl nest.

BEHAVIOUR, FORAGING & DIET

Secretive and almost entirely nocturnal, with vocal activity noted throughout the year and especially during the breeding season when adults call at all hours of the night, sometimes for an hour or more. Vocalising adults are occasionally seen perched in full view, clinging to a slender branch or hanging vine with the effort of each call causing their head and upper body to be thrown forward. Fledged young were noted in successive years at Hang Tau making distinctive hissing noises whilst wriggling and twisting on a perch. All activity and feeding was by night, and by day the youngsters roosted together in cover in a shady tree at heights of 3-8 metres above the ground whilst one or both adults were positioned below (Holmes & Holmes 2010).

The remains of Coleoptera and small mammals such as mice and shrews have been found in pellets under nest-trees (Vaughan & Jones 1913). At Hang Tau, a sparrow-sized passerine was fed to the young and an unidentified frog or toad which the young declined to take was swallowed whole by the adult (Holmes & Holmes 2010). Other food items reported are a Masked Laughingthrush and a large rat Rattus sp. brought to a juvenile at Po Fu Lam, and a Hawk Moth caught by an adult in shrubland in autumn.

RANGE & SYSTEMATICS

Distributed mainly as a resident from northeast Pakistan through the Himalayas to east Nepal and Assam to Myanmar, north Indochina, southeast China and Taiwan. Polytypic, with five subspecies recognised including erythrocampe in southeast China and endemic island forms on Hainan (umbratilis) and Taiwan (glabripes). According to Konig & Weick (2008), some DNA evidence suggests that erythrocampe may be specifically distinct.

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.