Mesites and roatelos

(Mesitornithidae)

Class Aves

Order Gruiformes

Suborder Mesitornithes

Family Mesitornithidae

Thumbnail description
Medium-sized birds with long, wide tails, short, round wings, well-developed legs, and decurved bills

Size
11.8–12.6 in (30–32 cm)

Number of genera, species
2 genera; 3 species

Habitat
Forest, woodlands, and thicket

Conservation status
Vulnerable: 3 species

Distribution
Madagascar

Evolution and systematics

The mesites are thought to be related to the rails (Rallidae), due to anatomical similarities such as breastbone structure. There are also differences, including five pairs of powder-downs and a lack of pervious nostrils. Like other Madagascan families, the mesites are the result of an ancient evolutionary offshoot, and while no fossils have been found, their uniqueness merits them their own suborder (Mesitornithes).

There are two genera: Mesitornis, including the white-breasted mesite (Mesitornis variegata) and the brown mesite (Mesitornis unicolor), and Monias, which has only one species, the subdesert mesite (Monias benschi). The distinction between the genera is based on bill form and egg form and structure. The species in the genus Mesitornis are also known as roatelos.

Physical characteristics

Mesites have an unusual, cylindrical profile, with thick undertail-coverts and a long, wide tail. The wings are short and round, and the legs are well developed. The bill, which is decurved, is adapted for foraging on the forest floor. Length is 12–12.5 in (30–32 cm), and only the subdesert mesite exhibits sexual dimorphism.

Distribution

The mesites are endemic to Madagascar. The brown mesite has the largest distribution, inhabiting forests in the east of the island. The white-breasted mesite is found primarily in patches of forest in the west and north, and the sub-desert mesite occupies a strip of forest 125 mi (200 km) long and 50 mi (80 km) wide between the coast and the hills in the southwest.

Habitat

Three main forest and woodland types are occupied: the lowland humid forests of the east (brown mesite), the dry deciduous forests of the west and north (white-breasted mesite), and the more open, spiny thickets of the southwest (subdesert mesite).

Behavior

Mesites are thought to be diurnal and, although able to fly, spend much of their time on the ground. Their bobbing gait is reminiscent of a pigeon, breaking into a run or short flight only when threatened. Social units vary in size from three birds in the brown mesite and white-breasted mesite (pair with most recent young) to six or 10 birds in the sub-desert mesite (within-group relationships not established).

All three species have a wide vocal repertoire—paired duets are common in the white-breasted and brown mesites—and utter a similar alarm call. Subdesert mesites will vocalize at the sound of another group approaching their territory. Both white-breasted and subdesert mesites engage in territorial disputes.

Feeding ecology and diet

The two Mesitornis species feed amongst the leaf litter, searching for invertebrates, seeds, and small fruits. The bill is positioned to allow them to lift fallen leaves without flicking them over, thereby minimizing disturbance to potential prey. The longer and more decurved bill of the subdesert mesite is better suited to probing the ground for invertebrates, although it too will take items from the litter.

Reproductive biology

The subdesert mesite is thought to be polygamous, while the two Mesitornis species are monogamous. The nests of all three are simple platforms of sticks, in low bushes or forked branches 2–10 ft (0.6–3 m) above the ground. Clutches of one to three eggs are laid during the rainy season, October through April. The incubation period is unknown, and parental responsibilities vary between species. The chicks are precocial and covered with reddish or blackish brown down. They tend to remain with the parents post-fledging, for up to a year in the case of the white-breasted mesite.

Conservation status

All three mesites are classed as Vulnerable due to population declines and decreases in habitat extent and quality. The Madagascan forests are under pressure from slash-and-burn cultivation, charcoal production, and commercial timber extraction. None appears readily able to recolonize areas of regenerating forest, which is a concern. Hunting, and predation by dogs and rats may be significant locally. Conservation areas cover a portion of the populations of the two Mesitornis species, but the level of protection afforded is low. The dry, spiny thickets of the southwest, home to the subdesert mesite, are entirely unprotected; a series of community-based conservation areas has been proposed.

Significance to humans

The mesites are all hunted for food, and are well known among local peoples. The brown mesite is not hunted in part of its range, due to a taboo that ranges from engendering human-like respect, to not speaking the bird's name, to simple terror.

Species accounts

List of Species

White-breasted mesite

Mesitornis variegata

taxonomy

Mesites variegata I. Geoffroy Saint-Hilaire, 1838, Madagascar. Monotypic.

other common names

English: White-breasted roatelo; French: Mésite variée; German: Kurzfuss-stelzenralle; Spanish: Mesito Pechiblanco;.

physical characteristics

12 in (31 cm); male 3.5–4.0 oz (103–111 g), female lighter. Upperparts rufous brown; throat, eyebrows, and breast pale cream; black crescent-shaped markings on sides of breast and upper belly; nape may be gray.

distribution

Madagascar. Small patches of forest in the west and north of the island, and Ambatovaky in the east.

habitat

In the west and north: dry, deciduous forest on sandy soils, with sparse understory and thick leaf litter. In the east: lowland humid forest. Sea level to 1,150 ft (350 m).

behavior

Terrestrial and secretive. Sedentary; usually found in family groups that defend territories year round.

feeding ecology and diet

Feeds among leaf litter and low vegetation, occasionally probing the soil, searching for invertebrates and plant seeds.

reproductive biology

Thought to be monogamous. Nests 3–9 ft (1–3 m) above the ground on a platform of sticks, October through April. Female incubates one to three eggs, period unknown. The young remain with parents for up to a year post-fledging.

conservation status

Vulnerable.

significance to humans

Hunted opportunistically, if irregularly, due to their small size.

Brown mesite

Mesitornis unicolor

taxonomy

Mesites unicolor Des Murs, 1845, Madagascar. Monotypic.

other common names

English: Brown roatelo; French: Mésite unicolore; German: Einfarb-stelzenralle; Spanish: Mesito Unicolor.

physical characteristics

12 in (30 cm); weights unrecorded. Upperparts rufous brown; underparts lighter. Rufous brown head may have pinkish gray tinge; chin and throat whitish tinged with rufous.

distribution

Eastern forests of Madagascar.

habitat

Lowland humid forest with sparse understory and thick leaf litter. Sea level to 3,600 ft (1,100 m).

behavior

Terrestrial and secretive. May move to different altitudes with the seasons. Often found in small family groups.

feeding ecology and diet

Probably similar to M. variegata, taking invertebrates from the forest floor.

reproductive biology

Breeds November through December. Only two nests found: both a platform of sticks 3–7 ft (1–2 m) above the ground, containing one egg. Incubation in both cases was by female, but period unknown.

conservation status

Vulnerable.

significance to humans

Hunted for food in the south of its range. Elsewhere hunting is restricted by taboo.

Subdesert mesite

Monias benschi

taxonomy

Monias benschi Oustalet and G. Grandidier, 1903, Vorondreo, Madagascar. Monotypic.

other common names

English: Monias, Bensch's rail; French: Mésite monias; German: Moniasstelzenralle; Spanish: Mesito Monias.

physical characteristics

13 in (32 cm); weights unrecorded. Relatively long, decurved bill. Grayish brown upperparts; light underparts; long, white eyebrows. Males have black crescent-shaped markings on underparts; females have rufous throat and breast.

distribution

Coastal forests in southwest Madagascar.

habitat

Dry, spiny thickets on sandy soils, with sparse understory and much leaf litter. From sea level to 430 ft (130 m).

behavior

Terrestrial and gregarious. Usually found in groups of two to six birds, rarely up to 10. If alarmed, the group will scatter, with birds either remaining motionless in shadow or flying onto low branches where they lie pressed to the bark.

feeding ecology and diet

Forages on the ground, probing the soil for invertebrates; occasionally takes prey and small fruits and seeds from leaf litter.

reproductive biology

May be polyandrous or polygynous. Breeds November through January. The simple stick nest is built 2–7 ft (0.6–2 m) above the ground, and contains one or two eggs. Parents share incubation and care of the blackish brown chick.

conservation status

Vulnerable.

significance to humans

Hunted for food.

Resources

Books

BirdLife International. Threatened Birds of the World. Cambridge, UK: BirdLife International, 2000.

Dee, T. J. The Endemic Birds of Madagascar. Cambridge, UK: International Council for Bird Preservation, 1986.

Evans, M. I., A. F. A. Hawkins, and J. W. Duckworth. "Family Mesitornithidae (Mesites)." In: Handbook of the Birds of the World, Vol. 3. Hoatzin to Auks, edited by J. del Hoyo, A. Elliott, and J. Sargatal. Barcelona: Lynx Edicions, 1996.

Langrand, O. Guide to the Birds of Madagascar. New Haven & London: Yale University Press, 1990.

Morris, P. and F. Hawkins. Birds of Madagascar: A Photographic Guide. East Sussex, UK: Pica Press, 1998.

Periodicals

Hawkins, A. F. A. "Conservation Status and Regional Population Estimates of the White-breasted Mesite Mesitornis variegata, a Rare Malagasy Endemic." Bird Conservation International 4 (1994): 279–303.

Seddon, N., J. Tobias, J. W. Yount, J. R. Ramanampamonjy, S. Butchart, and H. Randrianizahana. "Conservation Issues and Priorities in the Mikea Forest of South-west Madagascar." Oryx 34, no. 4 (2000): 287–304.

Turner, A. D. "A Note on Bensch's Rail Monias benschi from Madagascar." Bull. British Ornithologists' Club 101, no. 1 (1981): 240–241.

Woodbury, C. J. "Two Spinal Cords in Birds: Novel Insights into Early Avian Evolution." Proceedings of the Royal Society of London Series B-Biological Sciences 265 (1998): 1721–1729.

Organizations

African Bird Club, c/o BirdLife International. Wellbrook Court, Girton Road, Cambridge, Cambridgeshire CB3 0NA United Kingdom. Phone: +44 1 223 277 318. Fax: +44-1-223-277-200. E-mail: [email protected] Web site: <http://www.africanbirdclub.org/>

Other

BirdLife International. "Saving Species Factsheets." (31 January 2002). <http://www.birdlife.net/species/index.cfm?GeoRecID=126>

David G. Hoccom, BSc (Hons)