Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The population was estimated at between 400-500 pairs in 1988 (Robinson 1988 cited in Garnett et al. 2011). This is anticipated to have declined subsequently, hence the population is considered to presently be below 1,000 mature individuals, all in a single subpopulation.
While the population has been mentioned as appearing ‘secure’ since 1997, and this may be the case that inside the national park there has been little change since that time, there also have not been sufficient monitoring efforts anywhere to reliable gauge the trend. The anecdotal evidence provided in Garnett et al. (2011) in fact suggests that there may be an ongoing decline outside the park and the population was classified on a precautionary basis to be declining.
This species is endemic to Norfolk Island (to Australia), where it is now largely restricted to the National Park (Garnett et al. 2011). On the island the area of occurrence (AOO) has been estimated to be 8km2, with the species having been lost from the majority of the island and now largely restricted to the National Park (Garnett et al. 2011). Outside the park the population may have numbered up to 100 pairs in the 1980s (Department of the Environment 2016), but Garnett et al. (2011) reported the absence of birds from recently occupied sites in the first decade of this century.
It inhabits mature rainforest, occasionally palm and introduced olive (Olea) stands, rarely exotic eucalypt (Eucalyptus) forest; prefers forest no taller than 10 m, and having rather open ground layer with deep moist leaf litter (Boles and Sharpe 2016).
Historically there has been extensive clearance for timber, cultivation, pasture and continued development. Ongoing threats include invasive rats, cats and exotic vegetation, which are all still present on the island (although subject to control measures over part of the island).
Text account compilers
Butchart, S., Ekstrom, J., Symes, A. & Westrip, J.
BirdLife International (2019) Species factsheet: Petroica multicolor. Downloaded from http://www.birdlife.org on 17/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/11/2019.