Data Zone
Justification of Red List category
This species is classified as Endangered because it has a very small population which is declining through forest loss and degradation for subsistence farming as well as extractive logging.
Population justification
The species is currently thought to be very rare and is currently known from only one area on Nendo, although it is suspected to occur at others. 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 1933, Gibbs 1996, G. Dutson pers. obs. 1997, T. Leary in litt. 2000). This species 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). This is in spite of reasonable detectability once pairs were found (Pierce 2014). Approximated densities and encounter rate are also similar 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). Applying a density of one pair (two mature individuals) per km2, and a total area of 470 km2 of forest in 2021 (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein), the population is estimated to be a maximum of 940 mature individuals. However, large areas of forest appear not to be occupied (G. Dutson in litt. 2022), and the population size is therefore estimated at 250-999 mature individuals, however it may possibly even number <250.
Trend justification
This species appears to be confined to old-growth areas of good forest and is absent from all degraded habitat types including secondary forest and gardens (Pierce 2014, G. Dutson in litt. 2021). Since the island was once entirely old growth forest, and the species now appears absent from these areas, declines are inferred to have taken place in the past. Habitat degradation on Nendo is ongoing (Global Forest Watch 2022, using Hansen et al. [2013] and methods therein) and the western side of the island is now replete with logging tracks (Global Witness 2018, M. O'Brien in litt. 2021) that may accelerate these losses in the future. The impacts of rats (Rattus rattus) and Wasmannia fire ants are unknown but concern, especially on the latter, has been raised (R. Pierce pers. comm., M. O'Brien in litt. 2021). The rate of ongoing declines is, however, unknown and requires urgent confirmation given the small population size of this species.
Clytorhynchus sanctaecrucis is endemic to Nendo in the Santa Cruz Islands of the Solomon Islands (Dutson 2006, 2011).
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 principal threat to this species is logging, even where it does not cause perceptible alterations in forest cover extent according to remote sensing data (G. Dutson in litt. 2021, M. O'Brien in litt. 2021). All observations of this species have been in pristine forest with a high canopy and developed understorey (e.g. Pierce 2014), such that even minor modifications to forest integrity are thought to make areas of habitat unsuitable. There has been a recent increase in the number of logging tracks on the island (Global Witness 2018) and mining corporations reportedly have plans for development (M. O'Brien pers. comm. 2019). The susceptibility of birds on these islands to invasive alien species such as Wasmannia ants and 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
Berryman, A.
Contributors
Dutson, G., Leary, T., Pierce, R. & O'Brien, M.
Recommended citation
BirdLife International (2024) Species factsheet: Nendo Shrikebill Clytorhynchus sanctaecrucis. Downloaded from
https://datazone.birdlife.org/species/factsheet/nendo-shrikebill-clytorhynchus-sanctaecrucis on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.