Data Zone
Justification of Red List category
This species is classified as Vulnerable because population declines are predicted to become rapid over the next three generations owing to the destruction and degradation of its forest habitat.
Population justification
The population is inferred to number 2,500-9,999 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 is equivalent to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals. The true population size may lie at the upper end of this estimate, as while the species is described as uncommon it can be easily overlooked and so may be more common than has previously been believed (Collar and Stuart 1985).
Trend justification
This species is inferred to be declining due to ongoing forest loss across its range (Global Forest Watch 2021). Between 2001-2019, this species experienced forest cover loss of 27% (Global Forest Watch 2021). Assuming that the population declines at a similar rate, this equates to a decline of 23% over 3 generations. Hence, the past rate of decline is placed in the band 20-29%. Climate change modelling has also shown this species's ecological niche may decline by c.45% due to climate change over the 50 year period from 2000 to 2050 (Andriamasimanana and Cameron 2013). Between 2016-2019, this species experienced forest cover loss of 11% (Global Forest Watch 2021). Assuming that the population declines at a similar rate, projected forward over 3 generations, this would equate to a loss of 44%. Hence the suspected future rate of decline is placed in the band 30-49%.
This species is found only below 1,000 m asl and thus is one of the few true lowland rainforest species in Madagascar. It occurs in lowland forest throughout the eastern rainforest belt from Marojejy south to Andohahela. However, there is much less lowland forest in the southern part of this belt (ZICOMA 1999).
This species seems to prefer low-altitude areas of undisturbed, primary rainforest with damp soils, dark and tangled undergrowth, low herbaceous vegetation and a layer of leaf-litter and branches (Langrand 1990). However, it may be able to tolerate degree of habitat degradation, because it has recently been observed in edge habitats and secondary growth (Langrand 2013). It feeds on invertebrates, chiefly earthworms but also snails, centipedes, spiders, ants and beetles, and more rarely small vertebrates (e.g. frogs) (Langrand 1990). It nests in a tunnel, dug in a bank or slope in the forest, between October and January.
The principal threat to its forest habitat is from slash-and-burn cultivation by subsistence farmers, which results in progressively more degraded regrowth and leads eventually to bracken-covered areas or grassland (Stattersfield et al. 1998). Much of the forest on the eastern coastal plain has either already been cleared or is highly degraded, remaining habitat is under pressure from the increasing human population and commercial logging is an additional threat in some areas (Jenkins 1987; ZICOMA 1999). If present trends continue, the remaining unprotected forest, especially at the lower altitudes where this species is more abundant, will disappear within decades (Stattersfield et al. 1998). Subsequently, this species may be under increased risk because of its greater dependence on lower altitude rainforest than most other Malagasy species, despite its range (Langrand 2013). Predation by village dogs and hunting for food are possibly threats (ZICOMA 1999). Climate change may also lead to future declines in its ecological niche (Andriamasimanana and Cameron 2013)
Conservation Actions Underway
The species is known from the following protected areas: Ambatovaky Special Reserve, Andohahela National Park, Andringitra National Park, Anjanaharibe Classified Forest, Anjanaharibe-South Special Reserve, Betampona Strict Reserve, Haute Rantabe Classified Forest, Mananara-North National Park, Mantadia National Park, Marojejy National Park, Masoala National Park, Midongy-South National Park, Ramanofana National Park, Tsitongambarika Classified Forest, Vondrozo Classified Forest and Zahamena National Park (ZICOMA 1999).
27-31 cm. Thickset, terrestrial bird with strong bill. Head covered in dense black-and-white scaly pattern. Coppery-brown mantle, greenish wings with whitish tips to coverts. Tail reddish-brown in centre, with blue tips and black subterminal marks to outer feathers. Black eye-stripe and line across cheeks, and paler underparts heavily marked with black crescents. Thick and fairly long, greyish bill. Long, pink legs. Similar spp. Combination of heavily scaled plumage, long pink legs and terrestrial behaviour make this bird unmistakable. Voice Call is low, emphatic boop, given once every 10 seconds or so. Hints Hops around on the floor of lowland rainforest, often in rather open areas, catching terrestrial invertebrates such as worms, beetles and cockroaches.
Text account compilers
Clark, J.
Contributors
Ekstrom, J., Evans, M., Hawkins, F., Rabenandrasana, M., Safford, R., Shutes, S., Starkey, M., Symes, A., Taylor, J. & Westrip, J.R.S.
Recommended citation
BirdLife International (2024) Species factsheet: Scaly Ground-roller Geobiastes squamiger. Downloaded from
https://datazone.birdlife.org/species/factsheet/scaly-ground-roller-geobiastes-squamiger on 23/12/2024.
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 23/12/2024.