VU
Short-legged Ground-roller Brachypteracias leptosomus



Justification

Justification of Red List Category
This species qualifies as Vulnerable because its small population is likely to be declining owing to the destruction and degradation of its forest habitat, and climate change is projected to cause declines in its ecological niche. This decline is likely to become rapid over the next ten years.

Population justification
The species can be easily overlooked and a study on Masoala peninsula estimated a density of 4 territories per km2, which would have equated to a maximum of approximately 8,800 pairs in the peninsula alone (Thorstrom and Lind 1999). Assuming a conservative measure of 10-25% occupancy of the EOO this would give a total of 3,900-9,800 pairs. This equates to 7,800-19,600 mature individuals.

Trend justification
Modelling the possible effects of climate change have shown that this species's ecological niche may decline by as much as 62% 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.26% decline in its ecological niche over its next 3 generations due to climate change alone. Further to this the population is suspected to be declining in line with habitat loss and degradation, and hunting pressure. If present trends continue, the remaining unprotected forest, especially at the lower altitudes preferred by this species, will disappear within decades (Stattersfield et al. 1998). Thus declines of this species within the next 3 generations may be within the 30-49% range.

Distribution and population

Brachypteracias leptosomus is fairly common within its restricted habitat of low- and mid-altitude primary forests in eastern Madagascar, from Daraina Forest in the north to Andohahela in the south (Langrand 1990).

Ecology

This secretive species is found solely in undisturbed, primary rainforest (Langrand 2013). At the upper part of its altitudinal range it occurs only where trees are large (Evans et al. 1992; ZICOMA 1999). It prefers forest with dark, humid areas, a moderate ground cover of herbaceous, mossy vegetation, and deep leaf-litter (e.g. Thorstrom and Lind 1999). The least terrestrial of the rainforest ground-roller species, it spends much time perched 2-15 m above ground on horizontal branches, searching for prey (Evans et al. 1992; Langrand 1990). It feeds on invertebrates (90%), often terrestrial, and also small vertebrates (10%) (Langrand 1990; Thorstrom and Lind 1999). It nests in tree cavities and the root masses of epiphytes, often around 20 m above the ground (Thorstrom and Lind 1999). The home range of one pair was 19ha, occurring over an altitudinal range of 5-200m within that 19ha; pairs occupied contiguous territories in this undisturbed habitat (Thorstrom and Lind 1999). The species appears able to re-nest rapidly after natural nest failure (Thorstrom and Lind 1999).

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, grassland or other non-forest vegetation (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). Climate change may also threaten its ecological niche (Andriamasimanana and Cameron 2013). If present trends continue, the remaining unprotected forest, especially at the lower altitudes preferred by this species, will disappear within decades (Stattersfield et al. 1998). The species is also hunted (ZICOMA 1999).

Conservation actions

Conservation Actions Underway
The species occurs in 23 Important Bird Areas (77% of the total in eastern Malagasy forest) and is found in nine National Parks, two Strict Reserves, three Special Reserves and six Classified Forests (ZICOMA 1999).

Conservation Actions Proposed
Carry out surveys in order to estimate the population size. Compare survey data collected from protected and unprotected areas (M. Rabenandrasana in litt. 2007). Conduct regular surveys to monitor population trends. Monitor rates of habitat loss and degradation. Improve the management of the eastern humid forests, especially the control of fires used in slash-and-burn cultivation. Pursue further ecological studies to 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. Conduct research into the level of hunting pressure on the species.

Identification

38 cm. Thickset, arboreal bird with large head and strong bill. Upperparts mid green-brown, with purple iridescence on rear crown and nape, and fine white tips to wing-coverts. Pale supercilium is short, steeply curved. Tail is fairly long, with white tips to the outer feathers. Underparts are paler, with brown throat and ear-coverts overlain with white spots, below which is a wide, white crescentic breast-band. Lower breast and belly are barred darker brown. Similar spp. Combination of purple nape, solid dark grey bill, white breast-band and white-tipped tail eliminate White-browed Owl Ninox superciliaris, the only bird which remotely resembles this species. Voice Call is a long series of bop notes, often given in early morning or evening, at a rate of about one a second. Hints Perches for long periods almost immobile.

Acknowledgements

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

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


Recommended citation
BirdLife International (2019) Species factsheet: Brachypteracias leptosomus. 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.