Justification of Red List Category
This species is classified as Endangered because it has a very small population which is declining through small-scale forest loss for subsistence farming. However the population estimate is based on few data and a poor knowledge of the area of suitable habitat on Nendo.
The species is only currently known from one area, although suspected to occur at over 10 locations across the remaining old-growth forest on Nendo. It appears to be restricted to old-growth forest, in which there are two indications of population density: two pairs along a 10 km transect (Dutson 2006) and 0.4 birds per hour (Pierce 2014). These are similar densities to the similar Black-throated Shrikebill C. nigrogularis in Fiji, which was recorded at an average of 0.1 birds (mostly calling males)/hour in old-growth forest, equating to one pair/km2 (G. Dutson in litt. 2005). Probably less than half of the EOO of C. santacecrucis (319 km2) is occupied suitable habitat (G. Dutson pers. comm. 2016), suggesting that the total population is probably 250-1,000 mature individuals but possibly <250 mature individuals.
It is suspected to be in declining at a slow to moderate rate owing to ongoing habitat loss and degradation caused mainly by industrial logging and shifting agriculture. An analysis of global forest cover data suggests that forest is being lost in the species range at 1.2% over three generations (Tracewski et al. 2016).
Clytorhynchus sanctaecrucis is endemic to Nendo in the Santa Cruz Islands of the Solomon Islands (Dutson 2006, 2011). It is known from two specimens taken in 1927, two pairs seen in 2004 (Dutson 2006) and two pairs seen in 2014 (Pierce 2014); other short surveys have failed to find the species, though these did not reach hill forest in interior Nendo (Mayr 1933a, Gibbs 1996, G. Dutson pers. obs. 1997, T. Leary in litt. 2000). In 1927, the Whitney expedition recorded just these two birds in seven days on Nendo. In 2004, two pairs were seen on a 10 km transect through suitable forest above Luselo (Dutson 2006). In 2014, two pairs were seen in primary forest and none in secondary forest or gardens (Pierce 2014). Local reports suggest that it is an uncommon species of old-growth forest (Dutson 2006).
It is known from rainforest near the summit of the island (550 m), at about 80 m (Dutson 2006) and at 100 m and 230 m (Pierce 2014). It has not been recorded in degraded forest and local reports suggest that it is only found deep in forest, perhaps usually beside streams or steep-sided gullies with a dense understorey (Dutson 2006, Pierce 2014). Pairs have been seen foraging at all levels, including on the ground, but otherwise behave as other shrikebills (Dutson 2006).
The lack of records from the degraded forest close to Lata suggest that it could be threatened by logging. Nendo's forests are currently suffering only a little degradation from slowly expanding agriculture and harvesting timber for local use. The susceptibility of birds on these islands to invasive alien species such as black rats Rattus rattus is unknown.
Conservation Actions Underway
None is known.
Identification 21cm. Males are almost pied with blue-glossed black upperparts, black head and throat, white ear-coverts, small white supercilium and white breast and underparts. Females are all rufous brown. Bill is slate blue-grey in both sexes. Similar spp. Black-throated Shrikebill Clytorhynchus nigrogularis. Plumage and behaviour distinctly different, also larger. Voice Loud mournful whistles c. 1-2 seconds long and repeated regularly.
Text account compilers
Derhé, M., Mahood, S.
Pierce, R., Leary, T., Dutson, G.
BirdLife International (2020) Species factsheet: Clytorhynchus sanctaecrucis. Downloaded from http://www.birdlife.org on 21/09/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/09/2020.