A Preliminary Assessment of Sifaka (Propithecus Spp.)
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Rakotonirina et al, Primate Conservation In press 1 A preliminary assessment of sifaka (Propithecus spp.) distribution, 2 chromatic variation and conservation in western central Madagascar 3 1,2 2 4 Laingoniaina Herifito Fidèle Rakotonirina , Fetraharimalala Randriantsara , 2 2 1,2 5 Andoniaina Harilala Rakotoarisoa , Rado Rakotondrabe , Josia Razafindramanana , 2 1 6 Jonah Ratsimbazafy and Tony King 7 1 8 The Aspinall Foundation, BP 7170 Andravoahangy, Antananarivo 101, Madagascar; 9 [email protected]; [email protected] 2 10 Groupe d’Etude et de Recherche sur les Primates de Madagascar (GERP), Lot 34 11 Cité des Professeurs Fort Duchesne, Ankatso Antananarivo 101, Madagascar 12 13 14 Abstract 15 16 To help inform conservation efforts for the Endangered crowned sifaka Propithecus 17 coronatus, we attempted to better define the known-distribution of sifakas in western 18 central Madagascar through field surveys of 17 sites we considered likely to fall 19 within or close to the historic range of P. coronatus. We observed P. coronatus at 20 seven sites, in the Boeny, Betsiboka and Bongolava regions. At three sites at the 21 intersection of the Bongolava, Melaky and Menabe regions we observed populations 22 containing sifaka of P. deckenii appearance mixed with melanistic individuals. We 23 observed P. verreauxi at the two most southerly sites, in the Amoron'i Mania Region, 24 and P. coquereli at one north-easterly site in the Betsiboka Region, a southern 25 extension of 90 km to the known range of the species. At the four remaining sites 26 sifaka appeared to be either absent or extinct. We observed two other lemur species, 27 Eulemur mongoz in the Boeny Region, and E. rufus in the Betsiboka Region, the latter 28 observation representing a small extension to the known range of the species. We 29 noted variation in pelage coloration amongst the P. coronatus individuals we 30 observed, mainly regarding the extent and tone of the rufous wash on the back, arms 31 and legs, but also in the color of the head, and the presence or absence of dark patches 32 on the nape or at the root of the tail. The melanistic forms of P. deckenii varied 33 greatly, some being very dark brown on large areas of the head, back, arms and legs, 34 and appearing unlike any typical sifaka species, others exhibiting an intermediate 35 coloration fairly similar to P. coronatus. We therefore suggest that P. coronatus 36 should not be considered to represent an extreme melanistic form of P. deckenii, and 37 that most previous reports of possible sympatry between the two taxa might 38 alternatively be explained by a melanistic tendency in P. deckenii, possibly arising 39 from occasional gene flow from P. coronatus. Our results show that P. coronatus may 40 now be considered widely distributed through western central Madagascar, but most 41 forests in this area are small and fragmented, and sifaka populations are highly 42 endangered. We therefore recommend the implementation of immediate conservation 43 interventions to ensure the maintenance of the full range of chromatic and genetic 44 diversity of P. coronatus. 45 46 Key-words: Propithecus coronatus, Propithecus deckenii, Propithecus coquereli, 47 Eulemur rufus, Eulemur mongoz, gene flow, melanism 48 49 50 1 Rakotonirina et al, Primate Conservation In press 51 Introduction 52 53 The crowned sifaka Propithecus coronatus is classified by the IUCN (2010) as 54 Endangered. It appears to have a poorly-known range in the wild, with the largest 55 known populations surviving in the fragmented dry deciduous forests between the 56 Betsiboka and Mahavavy rivers in north-west Madagascar (Mittermeier et al. 2010; 57 Salmona et al. this issue). To the north and east of the Betsiboka river it is replaced by 58 Coquerel’s sifaka P. coquereli, and to the south and west of the Mahavavy river by 59 Decken’s sifaka P. deckenii (Mittermeier et al. 2010). Populations of P. coronatus 60 have also been reported in fragmented forests in the Boeny and Bongolava regions 61 south to Tsiroanomandidy and the Sakay River (Milne-Edwards and Grandidier 1875; 62 Tattersall 1986; Thalmann et al. 2002; Mittermeier et al. 2010), and the most 63 southerly known site has recently been discovered in the Menabe Region near 64 Miandrivazo (Razafindramanana and Rasamimanana 2010). To the south and south- 65 west of its range the species is replaced by Verreaux’s sifaka P. verreauxi 66 (Mittermeier et al. 2010; Razafindramanana and Rasamimanana 2010). 67 68 This general distribution of these four sifaka species is, however, not quite as neat as 69 we have just described. Several taxonomic and distributional issues regarding this 70 group remain unresolved. Historically, many authors considered them all as 71 subspecies of P. verreauxi (Hill 1935; Petter et al. 1977; Tattersall 1982), whilst 72 others have proposed that P. coronatus and P. deckenii are a single taxon, either as a 73 monospecific P. deckenii, or as a single subspecies of P. verreauxi (Tattersall 1988; 74 Pastorini et al. 2001). Several authors have given detailed syntheses elsewhere 75 (Thalmann et al. 2002; Groves and Helgen 2007; Mittermeier et al. 2008, 2010), so to 76 summarize, much of this discussion concerning P. coronatus and P. deckenii arises 77 from the observation that sifaka populations in the northern reaches of the Mahavavy 78 river are generally either of P. coronatus coloration to the east (white body with a 79 predominantly black head) or of P. deckenii coloration to the west (white body with a 80 white head), whilst several observations further south include individuals resembling 81 both forms (Curtis et al. 1998; Randrianarisoa et al. 2001b; Thalmann et al. 2002), or 82 melanistic forms which resemble neither species (Petter and Peyrieras 1972; Petter et 83 al. 1977). Further confusion appears to have arisen from equivocal interpretations of 84 written descriptions of pelage variation given in older publications that generally lack 85 photographs or illustrations, and also to some extent the lack of precise coordinates 86 for some observations. 87 88 These unresolved issues have several consequences for conservation, not least 89 because the conservation status of a taxon depends on which populations are included 90 within that taxon, and also because in developing a conservation program, planners 91 need to define what they are attempting to conserve (Blair et al. 2011). They also need 92 to be confident they know the distribution of a taxon, in order to be able to assess its 93 abundance and status, and to design appropriate conservation interventions 94 (Rakotonirina et al. 2011). Within the framework of a conservation project for P. 95 coronatus (The Aspinall Foundation 2009, 2010), we therefore attempted to better 96 define the known-distribution of the species through field surveys of sites in western 97 central Madagascar we considered likely to fall within or close to its historic range. In 98 this paper we present the results of our work to date, including newly-reported sites 99 supporting sifakas, descriptions and photographs of the pelage variation we found 2 Rakotonirina et al, Primate Conservation In press 100 within sifaka populations at these sites, and preliminary assessments of the threats 101 facing the sites. 102 103 Methods 104 105 We surveyed 17 sites in 16 communes of six administrative regions of western central 106 Madagascar (Table 1). The six most northerly sites were at low altitude (12 to 384 m) 107 in the Boeny and Betsiboka regions, the remaining 11 sites were at mid to high 108 altitude (657 to 1339 m) in the Bongolava, Melaky, Menabe and Amoron'i Mania 109 regions. We undertook several missions between January and December 2010 to 110 survey all these sites (Table 1). We consulted local authorities and local populations 111 in each zone before selecting the precise localities for our surveys at each site. 112 Accompanied by local guides and at some sites by local gendarmes, we searched for 113 sifaka following paths in the forest or by walking along the edge of forest patches or 114 gallery forests. On each occasion that we observed sifaka, we took a GPS point and 115 noted the date and time of the observation, the size of the group, the sex and age-class 116 of each individual wherever possible, and described their coloration. We also noted 117 the presence of any other lemur species we encountered, and any evidence of threats 118 to the sites. Lemur nomenclature follows Mittermeier et al. (2010), and vegetation 119 classifications follow Moat and Smith (2007). 120 121 Boeny Region 122 123 The largest known populations of P. coronatus occur in the Boeny Region, 124 particularly in the communes of Katsepy, Antongomena Bevary and Mitsinjo, and 125 have been the focus of several studies (Curtis et al. 1998; Muller et al. 2000; Pichon 126 et al. 2010; Salmona et al. this issue). This region was therefore not a priority area for 127 our surveys. However we did survey one site in the region, Anaboazo in the commune 128 of Ambato Boeny, as we received reliable information regarding the presence of the 129 species in this unprotected and previously unsurveyed forest (M. Mbaraka, pers. 130 comm.). The region is the most forested of those we surveyed, consisting of 131 fragmented western dry forest and wooded grassland - bushland and plateau grassland 132 – wooded grassland mosaics (Moat and Smith 2007). 133 134 Betsiboka Region 135 136 We surveyed five sites in the Betsiboka Region, which apparently had no previously 137 published sites supporting P. coronatus populations; the Kasijy Special Reserve is 138 located in this region, but supports primarily P. deckenii, with only a few reported 139 individuals resembling P.