Justification of Red List Category
This species is listed as Vulnerable because its habitat is becoming increasingly fragmented, its Extent of Occurrence and the area and quality of suitable habitat are decreasing, and thus its small population is suspected to be declining rapidly. Climate change may also lead to declines in its ecological niche in the future.
The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.
The population is suspected to be rapidly declining, in line with the clearance and degradation of rainforest for subsistence agriculture and timber extraction, as well as mortality from hunting and introduced predators. Also, modelling the possible effects of climate change have shown that this species's ecological niche may decline by 99.7% due to climate change over the 50 year period from 2000-2050 (Andriamasimanana and Cameron 2013). Assuming a linear decrease, this would equate to a c.37% decline in its ecological niche over the next 3 generations from climate change alone. Considering the possible impacts from other factors, the future decline is placed in the range of 30-49% (c.25% in the next two generations, c.12% in the next generation).
Mesitornis unicolor has a patchy distribution in the eastern rainforest of Madagascar (Morris and Hawkins 1998), known for certain from as far north as Marojejy and the Masoala Peninsula and extending almost as far south as Taolañaro (Fort Dauphin). It is thinly distributed and never common, although its status is difficult to ascertain as it is secretive and rarely seen.
This is a ground-dwelling species of undisturbed primary, evergreen, humid forest (Langrand 1990, Morris and Hawkins 1998). It occurs from sea-level to 1,200 m but is most frequently encountered below 800 m. It seems to prefer steep slopes and dark areas with much leaf-litter and little herbaceous growth (Langrand 1990, Morris and Hawkins 1998). It forages on the forest floor for seeds and small insects, often in family groups of two to three individuals (Langrand 1990), also gleaning from leaves and stems at ground-level (Evans et al. 1992). The nest is built 1-1.5 m from the ground; the clutch-size is one.
The species's rainforest habitat is under pressure from slash-and-burn cultivation by subsistence farmers, with commercial timber exploitation and hunting in some areas (Morris and Hawkins 1998, ZICOMA 1999). Climate change will likely lead to declines in its ecological niche in the near future (Andriamasimanana and Cameron 2013). Near villages, dogs and rats Rattus spp. may predate the species as it is a reluctant flier (Langrand 1990).
Conservation Actions Underway
The species is known from 14 Important Bird Areas in eastern Madagascar, including seven National Parks, one Strict Reserve, four Special Reserves and one Classified Forest (ZICOMA 1999).
30 cm. Slim, low-slung, terrestrial bird with small head. Dark brown on back, with paler, greyish head, variable white streak behind eye, and paler, pinkish underparts. Rather slim and short, greyish bill. Similar spp. Told from Madagascar Wood-rail Canirallus kioloides by long full tail, less pure grey on head, slim bill, and very horizontal posture. From White-breasted Mesite M. variegata by lack of conspicuous head pattern and even, mid-rufous brown underparts. Voice Song, rather rarely given, is a loud rolling chooi-whoop-chooi-whoop chooi-whoop. Hints Walks slowly around, looking for invertebrates in the leaf-litter by flicking over leaves with its bill.
Text account compilers
Khwaja, N., Shutes, S., Evans, M., Starkey, M., Symes, A., Taylor, J., Westrip, J., Ekstrom, J.
BirdLife International (2019) Species factsheet: Mesitornis unicolor. Downloaded from http://www.birdlife.org on 18/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/11/2019.