Schildkröten im Fokus Online, Bergheim 2013: 1: 1–8 Ryan C. J. Walker

The status of wild populations of the Critically Endangered Madagascar spider tortoise Pyxis arachnoides.

Text and photos by Ryan C. J. Walker

Introduction (Walker et al. 2007). The species dynamics of the species, there is still The Madagascar spider tortoise (Pyxis inhabits the biologically unique dry very little knowledge of the species’ arachnoides Bell, 1827) is a small, coastal spiny forests of southwest biology. cryptic species endemic to southwest Madagascar (Pedro­no 2008, Walker Rhodin et al. (2011) describe Mada­gas­car (Fig. 1). This is one of the et al. in press; Fig. 2), one of the most P. arachnoides as one of the world’s smallest species of tortoise in the threatened habitats within Mada­gas­ top 40 threatened species of che­ world, with a domed carapace mea­ car (Har­per et al. 2007, Walker et al. lonian. Protecting wild populations suring up to 200mm (curved cara­ 2012a, 2012b). Despite a recent great­ of this species is a challenge due to pace length) in mature individuals er under­standing of the population the wide ranging conservation issues

Fig. 1 The small, cryptic spider tortoise (Pyxis arachnoides) within its coastal forest habitat of southwest Madagascar.

Schildkröten im Fokus Online 2013 (1) 1 Ryan C. J. Walker The status of wild populations of the Critically Endangered Madagascar spider tortoise

facing the tortoise. Since October 2005) (Fig. 3) with a plastral hinge (Walker et al. in press; Table 1). The 2004, CITES has placed a ban on mobility cline being the dominant cline in plasteral hinge mobility across the international trade in this spe­ defining physical characteristic across the subspecies has been speculated to cies (Walker et al. 2004) by listing three subspecies (Pedrono 2008). be an ecological adaptation to reduce it under Appendix I. However, illegal Pyxis arachnoides brygooi (Vuillemin moisture loss, as the environment tortoise collection and exportation & Domergue 1972) inhabits the becomes increasingly more arid the continues to be fueled by the lucra­ north of the range and displays a rigid further south one travels throughout tive pet trade to some extent, with a hinge (Walker 2010, 2011). Pyxis the range. However, this idea has particular demand stemming from arachnoides arachnoides inhabits the never been rigorously tested and is the Southeast Asian market due to the centre of the range and has a semi mere speculation. recent economic development within mobile plasteral hinge (Fig. 4), whilst, Recent work by Walker et al. the region creating a growing market P. a. oblonga Gray, 1869, with its (in press) has discovered two small for exotic pets. Despite this, habitat completely mobile hinge inhabits the population showing signs of intergra­ loss is probably the greatest threat most southerly portion of the range dations (Fig. 3; Table 1) between P. a. facing the long term survival of the (Fig. 5). The southern subspecies also brygooi and P. a. arachnoides to the species (Walker et al. 2012b). often displays dark pigmentation to south of the Manombo River mouth the periphery of the plastron, in com­ and the region north of Toliara, then Current distribution parison to the completely pale plas­ between P. a. arachnoides and P. a. and population status tron displayed by the two more north­ oblonga within the Linta River mouth Pyxis arachnoides is thought to com­ erly subspecies (Bour 1981, Pedrono region. These populations support prise of three geographically divided, 2008). The species supports a current animals which show morphological distinct subspecies (Chiari et al. area of occupancy of 2,464 km² characteristics indicative of either

Fig. 2 Cap Sainte Marie Special Reserve home to one of the largest remaining populations of Pyxis arachnoides oblonga. The area is typi- cally dominated by coastal dry spiny forest.

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one of the two subspecies and also individuals displaying a mixture of both characteristics. This intergrada­ tion could have come about through the gradual aridification of southwest Madagascar since the late Pleistocene or early Holocene, (i.e. over the past ~12,000 years) (Burney 1993, 1997) allowing for the convergence of sub­ species now able to mix as a result of seasonal drying of the Manombo and Linta Rivers. Recent spatial studies to map the current area of occupancy of the species and spatially compare this against the suspected historical extent of occurrence by Walker et al. (in press) suggests that the original sus­ pected historical distribution of the species (Bour 1981), was thought to encompassed a continuous belt off 555 km of coastline (Pedrono 2008). However, the species is now confined to eight distinct, fragmented sub populations, with P. a. brygooi and P. a. oblonga having thought to have suffered range contractions of around 80 % (Walker et al. in press; Fig. 3; Table 1). P. a. arachnoides still supports a relatively wide distribution and covers an area of occurrence of Fig. 3 1,029 km² (Fig. 3; Table 1). Current area of occupancy of the fragmented relic population of Pyxis arachnoides The global population size cur­ within coastal southwest Madagascar; A= three sub populations of P. a. brygooi, B= 1 sub population of P. a. brygooi/P. a. arachnoides intergrades, C= 1 sub population rently stands at 664,980 tortoises (95 % of P. a. arachnoides, D= 1 sub population of P. a. arachnoides/P. a. oblonga intergrades, CI 492,680–897,550), with a mean E= 2 sub populations of P. a. oblonga showing a very narrow area, occupied to the east population density of 2.3 tortoises of the range P. a. oblonga. Graph by Walker & Rafeliarisoa (2012). per ha. across the range (Walker & Rafeliarisoa 2012). However, tortoise density varies widely within 1.2 % per year (Harper et al. 2007, on this species historically (Walker the range (Jesu & Schimmenti 1995, Walker et al. in press). Population et al. 2004). More recently, this illicit Walker et al. 2007, Pedrono 2008, matrix modeling for a population of trade, stemming mostly as a result Rakotondriamanga et al. 2011). tortoises within the Anakao region, of demand from southeast Asia has has reviled a population is decline of increased since early 2009 due to Threats 1.4 % per year (λ=0.983), with this Madagascar going through a period Currently habitat loss is the greatest population likely to become ecologi­ of political unrest resulting in a sud­ threat facing the long term survival of cally non viable towards the end of den increase in wildlife smuggling the spider tortoise (Walker et al. the next century. (Ramahaleo & Virah-Sawmy in 2012a, 2012b, Walker & Rafelia­ri­ Despite the species’ up listing press). There is some anecdotal evi­ soa 2012) with the southern dry from CITES Appendix II to Appendix dence to suggest that within some spiny forests diminishing at a rate of I, the pet trade has had a great impact regions of southwest Madagascar spi­

Schildkröten im Fokus Online 2013 (1) 3 Ryan C. J. Walker The status of wild populations of the Critically Endangered Madagascar spider tortoise Current area of occupancy (AOO) of each subspecies population of population subspecies each (AOO)of occupancy of areaCurrent Table1 posed protected areas or sites of proposed mineral extraction. Data reproducedfrom Data extraction. mineral proposed of sites or areas protected posed Gesamt Übergang (D)* Übergang x P.arachnoides a. P.(E)* oblonga a. (C)* P.arachnoides a. P.(A)* brygooi a. Übergang (B)* Übergang arachnoides P.x brygooi a. oblonga

Subspecies der tortoises have been collected for local consumption as bush meat (Fig. 6). It is thought that P. a. brygooi appears to have been hunted to extinction within some CurrentAOO(km²) of its former range by the Mikea tribe (Walker 2010) and has been 2464 1029 267 568 500 100 targeted particularly during peri­ ods of drought when other food sources have been scarce. The Madagascan Government % of current AOOin current of %

Protected AreasProtected has recently granted mining con­ cessions to large areas of the region 100 74 70 47 77 55 of the species current range, for the exploitation of mineral sands, pre­ dominately Ilménite (Walker et al. in press; Table 1). Recent spatial

proposed extraction extraction proposed analysis work by Walker et al. (in % current AOOin current %

, in addition to the extent of AOO for each population of tortoise that fall within existing or pro or existing within fall that tortoise of population each forAOO of extent the to addition in arachnoides , Pyxis press) revealed that 18.3 % of the spider tortoise range falls within areas 18 25 20 38 4 0 these proposed mineral extraction zones (Table 1), with currently, no impact mitigation plan in place

et al. (in press). (in al.Walker et for these or any other species or Unpromoted ProtectedAreaUnpromoted South SAPM Reserve, Special Marie Sainte Cap Area, SAPM Unnamed/Unpromoted ProtectedAreaUnnamed/UnpromotedSAPM Area, TsimanampesotseParkD,National TsinjoriakeProtected Tsimanampesotse ParkExtension, National Plateau South, Unnamed/Unpromoted ProtectedAreaUnnamed/Unpromoted South, Plateau CoastalSouthwestern Wetlands Mahafaly ProtectedArea, PK32-Ranobe ProtectedArea PK32-Ranobe Zone 3 - Mikea ForestParkNational Mikea - 3 Zone ProtectedArea –VelondriakeManaged Community2 Zone Complex,ProtectedArea Ihotry Mangoky ForestPark, National Mikea - 1 Zone habitats potentially impacted by this change in land use (Walker et al. in press).

Conservation measures National law in theory protects P.

Protected areas Protected arachnoides, with consumption of *Letters relate to the distribution of each subspecies within Figure3. within subspecies each of distribution the torelate*Letters tortoises prohibited, however national law has remained widely ineffective at preventing the per­ secution of the species and its habitat (Pedrono 2008). Pyxis arachnoides was included on the IUCN Red List of Threatened Species in 1986 as Indeterminate and then as Lower Risk- Conservation Dependent in 1994. Ilmenite, ZirconIlmenite, Zircon, GraniteZircon, Monazite, Ilmenite, Lime, Ilmenite, Granite, Lime, ZirconGranite,Lime,Ilmenite, Zircon, Ilmenite Zircon, N/A Its status was later elevated to

Proposed resource to be be resourceProposedto Vulnerable because of on-going habitat degradation and over-har­

extracted vesting. The status of this species was elevated to Critically Endangered on the IUCN Red List for Threatened Species on the basis of habitat loss and non sus­ tainable exploitation (criteria -

4 Schildkröten im Fokus Online 2013 (1) The status of wild populations of the Critically Endangered Madagascar spider tortoise Ryan C. J. Walker

A4cd + E) in 2008 (Leuteritz & Habitat degradation is the greatest forest loss due to predominantly wide Walker 2008), during the 2008 management issue facing the remain­ spread, small scale, non sustainable Madagascar Tortoise Red Listing ing wild populations of spider tortois­ fuel wood harvest. As a result, most Meeting in Antananarivo (Mitter­ es (Walker et al. in press; Pedrono of these protected areas are zoned so meier et al. 2008). 2008). With the exception of the two as to permit continued forest resource Until recently the Madagascar National Parks (Mikea Forest and use and are likely to suffer continu­ protected area network encompassed Tsimanampesotse) and Cap Sainte ing habitat degradation (Gardner woefully little of the biologically Marie Special Reserve, all new pro­ 2009, Gardner 2011) with contin­ unique southern dry forest region of tected areas in the region are IUCN ued, potential negative implications southwest Madagascar (Fenn 2003). category III, V or VI multiple-use for tortoise populations. However, as a result of a pledge made protected areas, co-managed by local Despite this apparent bleak out­ at the Vth World Parks Congress community associations (Walker et look for the species, there are a in Durban in 2003, Madagascar’s al. in press; Gardner 2011). These number of small scale, community government has increased the coun­ protected areas seek to simultaneous­ focused conservation initiatives being try’s protected area coverage three­ ly conserve biodiversity while pro­ currently driven forward for the spe­ fold through the Système d’Aires moting the sustainable use of natural cies. A USAID funded family plan­ Protégées de Madagascar, with most resources for poverty alleviation and ning project within the region that newly gazetted parks established by local development (Gardner et al. supports the last strong hold of P. 2012 (Rabearivony et al. 2010). 2008) and emphasise the avoidance of a. brygooi is having positive effects Currently 73.5 % of the remaining negative impacts on local communi­ on reducing local resource pres­ spider tortoise range occurs within ties through resource use restrictions. sure, in particular habitat loss due to these protected areas (Walker et al. It would be simplistic to assume that fuel wood harvesting (Harris et al. in press; Table 1). very much will change in terms of 2012). In addition to this a number

Fig. 4 Pyxis arachnoides arachnoides within the forests of Tsimanampetsotsa National Park.

Schildkröten im Fokus Online 2013 (1) 5 Ryan C. J. Walker The status of wild populations of the Critically Endangered Madagascar spider tortoise

Fig. 5 Plastral hinge mobility can be seen in this Pyxis arachnoides oblonga.

of local NGOs and researchers have genre endémique Malagache Pyxis Fenn, M. (2003): The spiny forest ecore­ developed incentivized conservation Bell, 1827 (Reptilia, Chelonii). – gion. – pp 1525–1530 in: Goodman, strategies, whereby local communi­ Bulletin Mensuel de la Société S. M. & J. P. Benstead (eds.): The ties and individuals are paid to col­ Linnéenne de Lyon 50: 154–176. Natural History of Madagascar. – lect biological data on the species. Burney, D. A. (1993): Late Holocene chang­ Chicago, Illinois, USA (University of These communities derive small, but es in arid southwestern Mada­gascar. – Chicago Press). significant amounts of income from Quaternary Research 40: 98–106. Gardner, C. J. (2009): A review of the monitoring the species and preserv­ Burney, D. A. (1997): Theories and facts impacts of anthropogenic habitat ing them in situ. These projects have regarding Holocene environmental change on terrestrial biodiversity in generally been successful conserva­ change before and after human colo­ Madagascar: Implications for the design tion tools; however larger areas of the nization. – pp 75–89 in: Goodman, S. and management of new protected species’ dwindling range need to be M. & B. D. Patterson (eds.): Natural areas. – Malagasy Nature 2: 2–29. targeted by such projects to prevent Change and Human Impact in Gardner, C. J. (2011): IUCN manage­ the species from further declines and Madagascar. –Washington, DC, ment categories fail to represent new, ultimately extinction within the wild. (Smithsonian Institution Press). multiple use protected areas in Chiari, Y., M. Thomas, M. Pedrono & Madagascar. – Oryx 44: 336–346. References D. R. Veites (2005): Preliminary data Gardner, C. J., B. Ferguson, F. Rebara, Bell, T. (1827): On two new genera of land on genetic differentiation within the & A. N. Ratsifandrihamanana tortoises. – Transactions of the Linnean Madagascar spider tortoise, Pyxis (2008): Integrating traditional values Society of London 15: 392–401. arachnoides (Bell, 1827). – and management regimes into Bour, R. (1981): Etude systématique du Salamandra 41: 35–43. Madagascar’s expanded protected area

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system: the case of Ankodida. – pp Rene de Roland, M. Rakoton­ Rhodin (eds.): Turtles on the brink in 92–103 in Mallarach, J. M. (eds.): dratsima, T. R. A. Andriamalala, Madagascar. – Proceedings of two Protected Landscapes and Cultural T. S. Sam, G. Razafimanjato, D. workshops on status and conservation and Spiritual Values. – Heidelberg Rakotondravony, A. P. Raseli­ma­ of Malagasy tortoises and freshwater (IUCN, GTZ & Obra Social de Caixa na­na & M. Rakotoson (2010): turtles. – Lunenburg, MA, U.S.A. Catalunya, Kasparek Verlag). Protected area surface extension in (Chelonian Research Monographs). Gray, J. E. (1869): Notes on the families Madagascar: Do endemism and Rhodin, A. G. J., A. D. Walde, B. D. and genera of tortoises (Testudinata), threatened species remain useful cri­ Horne, P. P. van Dijk, T. Blanck & and on the characters afforded by the teria for site selection? – Madagascar R. Hudson (2011): Turtles in Trouble: study of their skulls. – Proceedings of Conservation & Development 5: The Worlds 25+ Most Endangered the Zoological Society of London 35–47. Tortoises and Freshwater Turtles. – 1869: 165–225. Rakotondriamanga, T., J. Kala & J. M. Lunenburg, MA, USA (IUCN/SSC Harper, G., M. Steininger, C. Tucker, Hammer (2011): Population study of Tortoise and Freshwater Turtle D. Juhn & F. Hawkins (2007): Fifty Pyxis arachnoides brygooi (Vuillemin Specialist Group). years of deforestation and forest frag­ & Domergue, 1972) in the area sur­ Vuillemin, S. & C. Domergue (1972): mentation in Madagascar. – rounding the Village des Tortues, Ifaty Contribution to the study of the fauna Environmental Conservation 34: – Mangily, southwest Madagascar. – of Madagascar: description of Pyxoides 325–333. Madagascar Conservation and brygooi gen. et sp. nov. (Testudinidae). Harris, A., V. Mohan, M. Flanagan & Development 6: 45–49. – Annales de l’Université de R. Hill (2012): Integrating family Ramahaleo, T. A & M. Virah-Sawmy Madagascar 9: 193–200. planning service provision into com­ (in press): Community perception of Walker, R. C. J. (2010): The decline of munity-based marine conservation. illegal harvesting of Astrochelys radia- the northern Madagascar spider tor­ – Oryx 46: 179–186. ta and Pyxis arachnoides during and toise (Pyxis arachnoides brygooi). – Jesu, R. & G. Schimmenti (1995): A pre­ before the political crisis in arid Herpetologica 6: 411–417. liminary study on the status of a southern Madagascar: Some critical Walker, R. C. J. (2011): The develop­ population of Malagasy Spider tor­ challenges and some potential solu­ ment of a cost effective method for toise (Pyxis arachnoides Bell, 1927) tions. – In: Castellano, C. M., H. measuring the variation of area in from SW Madagascar. – pp 144–147 Randriamahazo, R. E. Lewis, R. contrasting scute pigmentation in in: Devaux, B. (eds.): Proceedings of Mittermeier, R. Hudson & A. G. J. chelonians. – Herpetological the International Congress of Chelonian Conservation. – Gonfaron, France, 6th–10th July 1995. Leuteritz, T. & R. Walker (Madagascar Tortoise and Freshwater Turtle Red List Workshop) (2008): Pyxis arach- noides. – In IUCN (2012): IUCN Red List of Threatened Species. – Version 2012.2. – Internet: www.iucnredlist. org, downloaded on 23 May 2013. Mittermeier, R. A., A. G. J. Rhodin, H. Randriamahazo, R. E. Lewis, P. P. van Dijk, R. Hudson & S. Rioux Paquette (2008): Vision sokatra gasy – Madagascar turtle vision. – Turtle and Tortoise Newsletter 12: 7–9. Pedrono, M. (2008): The tortoises and turtles of Madagascar. – Kota Kinabalu, Malaysia, (Natural History Fig. 6 Publications (Borneo)), 147 pp. A pile of discarded P. a. brygooi carapaces, the tortoises were probably consumed Rabearivony, J., R, Thorstrom, L. A. and discarded by nomadic livestock headers, probably from the Mikea tribe.

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Conservation and Biology 6: 149−154. Rafeliarisoa & S. Hamylton sions. – In: Castel­lano, C. M., H. Walker, R. C. J. & T. H. Rafeliarisoa (2012a): The effect of habitat deterio­ Randria­mahazo, R. E. Lewis, R. (2012): Status of the relict population ration on the long term survival of the Mitter­meier, R. Hudson & A. G. J. of the Critically Endangered Critically Endangered Madagascar Rhodin (eds.): Turtles on the brink in Madagascar spider tortoise Pyxis spider tortoise. – Biological Madagascar; Proceedings of two work­ arachnoides. – Oryx 46: 453–463. Conservation 152: 152–158. shops on status and conservation of Walker, R. C. J., C. E. Rix & A. J. Woods- Walker, R. C. J., L. Luiselli & T. H. Malagasy tortoises and freshwater tur­ Ballard (2004): The export of the Rafeliarisoa (2012b): Effects of tles. – Lunenburg, MA, U.S.A. endangered Madagascar spider tor­ habitat loss on the survival probabili­ (Chelonian Research Monographs). toise (Pyxis arachnoides) to support ty of the Critically Endangered the exotic pet trade. – Herpetological Madagascar spider tortoises (Pyxis Author Bulletin 90: 2–9. arachnoides). – Amphibia Reptilia 33: Ryan C. J. Walker Walker, R. C. J., A. J. Woods-Ballard 141–144. Nautilus Ecology, Oak House, Pond & C. E. Rix (2007): Population densi­ Walker, R. C. J., C. J. Gardner, T. H. Lane, Greetham, Rutland, LE15 7NW, ty and seasonal activity of the threat­ Rafeliarisoa, I. Smith & R. Razafi­ United Kingdom ened Madagascar spider tortoise manatsoa (im Druck): Conser­vation Department of Environment Earth (Pyxis arachnoides arachnoides) of the of the Madagascar Spider Tortoise and Ecosystems, The Open University, southern dry forests; South West (Pyxis arachnoides) amid changing Milton Keynes, MK7 6AA, United Madagascar. – African Journal of land use policy: Assessing the spatial Kingdom Ecology 46: 67–73. coincidence of relict populations with Email: [email protected] Walker, R. C. J., N. Whitmore, T. H. protected areas and mining conces­ Telefon: +44(0)7739 740 701

Fig. 7 This example of a Pyxis arachnoides oblonga within the south of the species‘ range shows the beauty and variation of some individual carapace patterning.

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