Habitat

Populations of H. griseus ssp. are found in a variety of habitats in Madagascar. H.g. griseus occurs in the eastern lowland and montane rainforests (Mittermeier et al., 1994; Tattersall, 1982). This subspecies is sympatric with H. aureus and H. simus in parts of Ranomafana National Park (RNP) and Andringitra National Park (ANP) (Sterling and Ramaroson, 1996; Tan, 1999, 2000; Wright, 1992). In RNP, H.g. griseus inhabits both undisturbed and disturbed forests where bamboo is interspersed with other vegetation (Tan, 1999, 2000). H.g. alaotrensis, in contrast, is confined to the marshes surrounding Lac Alaotra. The dominant vegetation growing in these wetlands is papyrus (family Cyperaceae) and reeds (family Poaceae), and bamboo is absent (Mutschler, 1999a; Mutschler and Feistner, 1995). Though lacking a well-defined geographic range, H. g. meridionalis is found in the south, specifically in the lowland rainforest of Station Forestière Mandena (10 km north of Tolagnaro) (Warter et al., 1987). Mandena is a degraded littoral forest with patchy areas of bamboo, and a relatively high density of H. g. meridionalis has been reported in an area without any bamboo (Mutschler and Tan, 2003). H.g. occidentalis has a disjunct distribution with isolated populations in the central west (Tsingy de Bemaraha, Forêt de Tsimembo, Bongolava Massif, Namoroka National Park, Baly Bay, and Tsiombikibo) and northwest (Manongarivo Special Reserve, Sambirano River valley, and along the coast between Maromandia and Beramanja, including the Ampasinidava peninsula) (Curtis et al., 1995; Goodman and Schütz, 2000; Hawkins et al., 1998; Petter and Andriatsarafara, 1987; Petter et al., 1977; Rakotoarison et al., 1993; Raxworthy and Rakotondraparany, 1988; Tattersall, 1982). In addition, an unconfirmed H. griseus ssp., which may be H. g. occidentalis, has been sighted in Ankarana Special Reserve in the north (Hawkins et al., 1990). These populations have been reported to live in dry to subhumid deciduous forests where bamboo may or may not exist (Mutschler and Tan, 2003).

H. aureus is known from few sites in southeastern central Madagascar, and its range is extremely restricted. Besides RNP and some forest fragments to the east (e.g., Tolongoina), this species occurs in ANP and in the forested corridor connecting these two protected areas (Goodman et al., 2001; Irwin et al., 2005; Mutschler and Tan, 2003; Sterling and Ramaroson, 1996; C. Tan, unpublished data). At Talatakely, RNP, H. aureus coexists with H.g.griseus and H. simus. This site was selectively logged in the mid-1980s and contains both woody and viny bamboos (Tan, 1999, 2000).

Current populations of H.. simus occur in limited localities in southeastern central rainforests, including the aforementioned RNP and ANP (Mutschler and Tan, 2003; Sterling and Ramaroson, 1996; Tan, 1999, 2000). Although H. simus may be associated with the presence of large woody bamboo, small remnant populations have been encountered in highly degraded areas, such as Kianjavato and Karianga, where there is little or no bamboo (Tan, 1999, 2000; C. Spoegler, personal communication). A recent survey in the central eastern region near Torotorofotsy (ca. 10 km northwest of Andasibe) revealed indirect evidence of H. simus(Dolch et al., 2004). If confirmed, this would be the northernmost population of H. simus. It should be noted, however, that both museum collection and subfossil records indicate that H. simus had been widely distributed throughout northern, northwestern, central, and eastern Madagascar, overlapping in ranges with H.griseus ssp. As recently as about 130 years ago, H. simus occupied the eastern rainforests, from the Bay of Antongil in the north to Vondrozo in the south (Godfrey and Vuillaume-Randriamanantena, 1986).

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