VU
Scaly Ground-roller Geobiastes squamiger



Justification

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 estimated 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 estimate 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 nay be more common than has previously been believed (Collar and Stuart 1985).

Trend justification
Modelling the possible effects of climate change have shown that 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). Assuming a linear decrease, this would equate to a c.17.5% decline in its ecological niche over its next 3 generations, from climate change alone. Habitat loss and degradation due to forest conversion have led to a suspected moderate decline in population over the last 3 generations. In line with all of these factors, the rate of decline is expected to become rapid over the next 3 generations (c.30-49% decline).

Distribution and population

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).

Ecology

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.

Threats

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

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).

Conservation Actions Proposed
Determine its home-range size and its dispersal capability across deforested areas, in order to clarify the impact of forest fragmentation on its population structure. Carry out surveys in order to estimate its population size. Compare relative abundance and densities in protected and unprotected habitat (M. Rabenandrasana in litt. 2007). Conduct regular surveys to monitor population trends. Monitor rates of habitat loss and degradation. Assess the potential threats from domestic dogs and hunting pressure. Increase the area of suitable habitat that has protected status.

Identification

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.

Acknowledgements

Text account compilers
Ekstrom, J., Evans, M., Shutes, S., Starkey, M., Symes, A., Taylor, J. & Westrip, J.

Contributors
Hawkins, F., Rabenandrasana, M. & Safford, R.


Recommended citation
BirdLife International (2019) Species factsheet: Geobiastes squamiger. Downloaded from http://www.birdlife.org on 22/07/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/07/2019.