IDENTIFICATION

VOCALISATIONS

Bouts of song can be heard day or night, especially around dawn and dusk, in fine weather or rain, and are noticeably more frequent and prolonged earlier in the season, from mid-March to early May, becoming much less frequent in June before almost ceasing in July, rendering the species more difficult to detect as the season progresses. Mimicry by other species, especially Black-throated Laughingthrush, is occasionally heard and is thought to account for claims of unseen birds on unusual dates.

The song is a series of loud (audible at distances of 1km or more), shrill, trisyllabic phrases ‘pee-pwee-hu’, from which derives the English colloquial name ‘brain fever’ bird. The interval between the phrases broadly decreases at the same time as the first two syllables rise in pitch imparting an increasingly frenzied tone during each song series. For some birds the second syllable is  breaks down and becomes very throaty.

After the territorial song, the most commonly heard utterance is what Rasmussen and Anderton (2005) refer to as a ‘series of short burry dRUu-dRUu’ given by the female.

DISTRIBUTION & HABITAT PREFERENCE

Large Hawk-Cuckoo occurs at all altitudes across widespread parts of the New Territories, locally on HK Island and Lantau, and occasionally on Lamma, Cheung Chau and Po Toi islands, with one record from Kowloon. Birds presumed to be on territory show a strong preference for areas of mixed shrubland (Lewthwaite and Yu 2007), but also occur at fairly high densities in forest, fung shui woods near villages, stands of trees next to marshes, fishponds and reedbeds, and occasionally in mangroves. Birds thought to be migrants have been recorded in shrubland and fung shui woods and occasionally in urban parks.

Its distribution in the breeding season appears remarkably stable over the past 20 years, based on results of the two Nightbird Surveys. The percentage of 1 km grid squares with records of the species was 58.8% in 2000-2001 (Lewthwaite and Yu 2007) and 58.5% in 2020-2021. A somewhat different picture emerges from a comparison of the results of the two breeding season surveys, with the percentage of 1 km grid squares with records falling from 19.7% in the Breeding Survey of 1993-1996 to 13.7% in the Atlas of 2016-2019. However, this apparent distributional decline may be an artefact of differences in methodology between the two surveys and may also reflect late season coverage of shrubland squares in the second survey.

OCCURRENCE

Large Hawk-Cuckoo is predominantly a summer visitor with some birds presumably also passing through on migration in spring and autumn (Figure 1). A very high proportion of records refer to birds in song, which has been noted between 4 February and 1 August. Over 98% of records occur in the months March-June, and only 0.6% in February and 1.4% from July to October. Numbers rapidly increase from the third week of March to peak in the third week of April, then remain relatively high for the next 4-5 weeks, before declining steadily through May and dropping sharply in June. Records thereafter are occasional in July and sporadic in August and September, with one further record in October. Extreme dates are 4 February 2017 and 16 October 2019.

The highest counts are from areas of closed-canopy mixed shrubland - 12 at Pun Shan Chau on 4 April 2000 and 10 between Wu Kau Tang and Tai Mei Tuk on 22 March 2001, Ma On Shan CP on 11 April 2009 and between Lam Tsuen and Tai To Yan on 19 April 2014. Larger numbers recorded in other habitats include eight at Mai Po NR on 13 April 2017 and five in forest in Tai Po Kau on 18 April 2020.

The first record was on HK Island in April 1860 (Swinhoe 1863), after which there were reports in only two further years up to 1955 (Herklots 1953, Dove and Goodhart 1955). A gradual increase in the number of records and sites is evident between 1959 and 1973, followed by a more rapid increase from the late 1970s. By the 1990s, it was regarded as a common summer visitor, mainly from the middle of March to the end of June (Carey et al. 2001), as in the present day.

BREEDING

There are no observations of young in a nest in HK, but a dead female whose oviduct contained an egg was found at Shek Kong on 5 May 1993 (Reels & Ades 1993) and single fledged juveniles have been reported on eight dates in July and August, the earliest on 12 July. Despite it being such a commonly recorded cuckoo, its host species are unproven, though two species have been observed apparently in close attendance of juveniles and are suspected of being foster-parents - Oriental Magpie at Kam Tin on 12 July 2004  and Masked Laughingthrush at Long Valley on 21 July 2013.

BEHAVIOUR, FORAGING & DIET

Unobtrusive, despite its size, and secretive, keeping to dense canopy. Adults usually sing from within a tree, usually from a leafy high branch, unusually in flight, and have also been observed on one occasion singing from on top of a telegraph post. The only observations of food items concern caterpillars and a probable mantis.

RANGE & SYSTEMATICS

Breeds from north Pakistan east through the Himalayas to Myanmar and China largely as far north as the Yellow River but north to Beijing in the east, and south through much of Indochina where it is recorded all year. Also winters in south India, the Greater Sundas, Philippines and Sulawesi (Payne 1997). In China, it breeds on Hainan, Taiwan and in southern and eastern provinces north to Liaoning but does not remain in winter except occasionally in southernmost Yunnan and possibly Hainan (Cheng 1987).

CONSERVATION STATUS

IUCN: Least Concern. Population trend stable.