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Swinehart - HERPETOLOGICAL JOURNAL Vol 13 pp 125-133(2003...

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Unformatted text preview: HERPETOLOGICAL JOURNAL, Vol. 13, pp. 125-133 (2003) GEOGRAPHICAL DISTRIBUTION OF THE ENDEMIC SARDINIAN BROOK SALAMANDER, E UPROC T US PLA T YCEPHAL US, AND IMPLICATIONS FOR ITS CONSERVATION ROBERTA LECIS AND KEN NORRIS School ofAnimal and Microbial Sciences, University ofReading, Whiteknights, PO Box 228, Reading, RG6 6A.], UK The Sardinian brook salamander, Euproctusplatycephalus, is a cryptically coloured urodele found in streams, springs and pools in the main mountain systems of Sardinia, and is classified as critically endangered by IUCN. General reviews ofthe mountainous range where salamanders occur are numerous, but very few field-based distribution studies exist on this endemic species. Through a field and questionnaire survey, conducted between 1999 and 2001, we report a first attempt to increase data on the present distribution ofE. platycephalus. A total of 14 localities where Sardinian salamanders are represented by apparently stable and in some cases abundant populations have been identified, as well as 30 sites where species presence has been recorded after 1991. Some 11 historical sites were identified which are no longer inhabited bythe species. The implications of this distributional study for the conservation of the species and for the realization of an updated atlas are discussed. Key words: amphibian decline, island endemic, range, Sardinian mountain newt INTRODUCTION The genus Euproctus (Urodela, Amphibia) consists of three endemic species. The Corsican brook salaman- der E. montanus is found on the island of Corsica and the Pyrenean brook salamander E. asper lives in the Pyr— enees between France and Spain. The Sardinian salamander E. platycephalus is a slender, cryptically coloured endemic that inhabits .pools and streams in the mountains of Sardinia. The conservation status of the three Euproctus species is listed as ‘strictly protected fauna species’ within the Bern Convention (1998). E. platycephalus is classified by IUCN as critically endan- gered, on the basis of its endemism and of an estimated population reduction of 80% over the last 10 years (IUCN, 2000). Habitat loss could be one of the main threats to Sardinian salamanders, due to a long period of drought over the island (which caused a water deficit of —46.6% compared to the island’s water requirements in 2000: Regione Sardegna 2000), resulting in small rivers and streams being completely or partially dry during the summer months. Remaining salamander habitats have become fragmented and sometimes threatened by an- thropogenic disturbance, pollution and eutrophication. Predation and/or competition due to the introduction of non-native species, such as Salmo trutta, which have been implicated as a threat to other salamanders (Read, 1998; Tyler et al., 1998; Knapp & Matthews, 2000), are further contributing factors that threaten the long—term survival of the species. This salamander is known to live in the eastern part of Sardinia, in the main mountain systems: Limbara in the north, Gennargentu in the centre, and Sette Fratelli, Gerrei and Sarrabus in the south (Colomo, 1999). Correspondence: R. Lecis, Via Cagna n.66, 09126, Cagliari, Italy. E—mail:robyl [email protected] Alcher (1975) undertook a detailed field investigation listing a total of 45 sites where the species’ presence was recorded, as adults or larvae. Puddu et al. (1988) pub- lished a general distribution map of the species in which its range basically overlaps with the mountainous areas of the island. Other distribution surveys and biblio— graphic sources do not add any information to the picture already described by these authors (Bluno, 1980; Rimpp, 1998). Knowing the distribution of a particular species is a key‘issue in studies of theoretical and applied ecology, biodiversity and metapopulation biology (Cowley et al., 2000). Besides being a fundamental goal in ecology, de- scribing and explaining the distribution of endangered species has major significance for their conservation (Beebee, 1996). There is still little information concern- ing amphibian distributions and their relevance to the conservation management of threatened or declining populations. These field—based surveys should be com- bined with attempts to identify critical distribution determinants for a particular species. Some widespread amphibians such as T riturus spe- cies, Rana temporaria and Bufo calamita in Britain, and endemics such as Chioglossa lusitanica in Portugal, have been extensively studied and their distribution documented with finely-scaled maps (Beebee, 1996; Teixeira et al., 2001). Another example is given by Delaguerre & Cheylan (1992), who present a detailed atlas of the Corsican herpetofauna, in which E. montanus distribution is described. Although the distri- bution map is not confirmed by recent field survey, it gives fundamental information for further studies. Many other amphibian species, some of them rare or endan- gered (such as the Sardinian salamander), need similar high-resolution distribution studies. This paper presents an assessment of the distribution of E. platycephalus, using data collected during a field 126 R. LECIS AND K. NORRIS survey across the geographic range of the species over three years of research, conducted to identify locations that currently hold salamander populations. Reports of apparent population declines in the species are dis— cussed, and information on its geographical distribution is used to assess potential threats to its persistence and long—term survival in various parts of its range. METHODS FIELDWORK SEASONS Distribution data were collected during fieldwork seasons in 1999, 2000 and 2001. Fieldwork usually started in mid-April and finished in late July or August. This generally corresponded with the main breeding season ofthe species (Puddu et (1]., 1988). Spring in Sar- dinia is usually mild and sunny with low precipitation (Delitala et (11., 2000). With summer approaching, water in the stream-beds diminishes gradually until most of the streams consist of a number of pools, either isolated or connected by very small water channels. The 1999 field season focused on documenting the large scale distribution and typical habitat of the ani— mals. At the end of it, six study sites were identified throughout the eastern part of the island (south, centre and north) and five sites surveyed in the south-west. During the 2000 field season, 14 sites were visited, in- cluding the six already known, and a questionnaire was distributed to forestry stations. In 2001, all known sites were re-visited, and 18 new sites (four in the south—west and 14 in the rest ofthe island) were surveyed, most of these suggested by replies to the Forestali questionnaire. FORESTALI QUESTIONNAIRE The Corpo Forestale e di Vigilanza Ambientale is a regional body in charge of controlling Sardinian terri— tory, water courses and forests (equivalent to a forestry service). The island territory is divided into a number of districts, each one under the control ofa forest station. The area is extensively patrolled by ‘Forestali’ workers, who usually have an excellent knowledge of the local flora and fauna and are able to give accounts of salaman— der presence or absence. The questionnaire was distributed to 79 forest stations all over the island in July 2000, in order to collect records of salamander distribu- tion (Table l). A coloured photograph and a description of the species were supplied too. As there is only one other urodele found in Sardinia (the cave salamander Speleomantes sp.) which occupies a different habitat from E. platycephalus, forest station accounts were con— sidered highly reliable. SELECTION OF SURVEY SITES The distribution survey was designed to identify streams supporting salamander populations at present, covering as evenly as possible the three areas ofthe east- ern part of the island: south, centre and north. Survey sites were selected by combining three main sources of information: personal field trips to various sites during the fieldwork seasons following the suggestions oflocal people and exploration ofthe territory; the collection of replies to the E. platycephalus questionnaire; literature reviews (Aleher, 1975', Puddu er al, 1988; Schenk er (1]., 1995; Rimpp 1998). Out of55 distribution survey sites, 51% were visited during the field seasons (with local collaborators and forest station workers, or on our own initiative) and the remaining 49% were obtained from the questionnaire replies and the distributional informa- tion existent at the beginning of this study. SALAMANDER SURVEYS The selected streams were surveyed for salamander presence at least once during each field season. The method used to assess E. platycep/za/us presence in a particular site was a careful observation of the chosen stream-bed at different altitudes, and in pools scattered along the water course. Searches took from 3-6 hrs, not ‘ considering the time necessary to reach the site. Ap- proximately 1 km of the water course was walked by a team ofthree/four people going upstream. In most cases, salamander presence was immediately confirmed as TABLE I. Text in English ofthe questionnaire distributed to forest stations in July 2000. QUESTIONNAIRE ON EUPROCTUS PL/t TYCEPHALUS 2000 Forest Station: Villages and Districts included: According to the field experience of Forestali personnel and their knowledge ofterritory and local fauna, is the species present in this area? If yes, has it been observed recently? When (year and month)? Where (locality, stream, if possibile IGM coordinates)? If it has not been observed recently, was the species present in the past? When? When was its presence last assessed? What could be the reasons for decline or absence of the species in the area (water pollution, drought, anthropic presence, fishing, predators)? Other useful information (description of observed individuals, population density, personal notes). DISTRIBUTION OF THE SARDINIAN BROOK SALAMANDER 127 TABLE 2. Environmental parameters collected during 1999, 2000 and 2001 field seasons in sites inhabited by E. plarycephalus: minimum, maximum and mean values. Minimum Maximum Mean 1999 2000 2001 1999 2000 2001 1999 2000 2001 Air temperature (°C) 20 16 13.5 28.5 30 27 23.4 25.7 23.6 Relative humidity (%) 48 45 40 79 85 75 63.9 59.4 55 Water temperature (°C) 12.5 11.7 12.7 24.5 24 21 17.9 17.2 16.2 Water pH 6.3 7 7 8.2 8.5 8.3 7 7.6 7.6 Water DO (mg/l) - 6 3.4 ~— 10.6 12 —— 8.1 7.7 soon as the first pools inhabited by the species were reached (these animals tend to aggregate in parts of the stream). The observation of one individual was also considered a sign ofthe presence ofa salamander popu— lation. The observation could take longer in the case of absence of the animals, because a longer tract of the stream was surveyed before ruling out the presence of salamanders. In this case, rocks and stones underwater were turned and the bottom of pools disturbed using a stick, in order to see ifany individual were hiding in the substrate. STREAM TYPES AND CHARACTERISTICS In each inhabited survey site, some environmental parameters were collected (air and water temperature, relative humidity, water pH and dissolved oxygen, Ta- ble 2). Most of these survey sites were mountain or hill streams flowing through the typical Mediterranean macchia covering most ofthe island. This landscape is dominated by scrub plants such as heather (Erica sp.), myrtle (Myrtus commum's), juniper (szz’pcrus commu— nis), olive (Olea europaea sylvestrz's), Cistus sp., and Pistacz'a lentz'scus, as well as holm and cork oak forests (Quercus ilex and Q. suber). A few sites did not conform to this broad habitat type. The pool at S.Nicolo Gerrei is a concrete water store located in a field dominated by grasses and brambles (Rubus sp.). The artificial lake (Laghetto) located near Tempio, also has a slightly dif- ferent vegetation structure as the area sun‘ounding the lake has been cleared. Funtana Urpis, between Isili and Villanovatulo, is an artificial pool built along a water- course. Pischina Urtaddala is a natural lake (already 7 __.._..,,..., , JIL 0.2m 130-430 400800 600800 9001000 10130- 1%)!) Altitude [m. asl] FIG. 1. Vertical distribution of sites inhabited by E. platycephalus. Mum bet irhabited sites identified by Voesenek et (21., 1987) apparently isolated in a limestone locality, but it actually depends on the overflow of the Rio Flumineddu stream. Streams and pools were completely open or canopy— covered, or partially protected by overhanging rocks or vegetation. There was one exception, where a very inter- esting hypogeous E. platycephalus population was found living in a stream flowing inside a cave (Is Angurtidorgiu, near Perdasdefogu). RESULTS DISTRIBUTION 015E. FLA TI'CEPHALUS Sardinian salamanders have a naturally patchy distri— bution across the island, showing association with small and temporary streams, pools and small lakes, ponds and springs, at a wide range of altitudes (from 100 to 1200 m) and with preference for sites between 400 and 800 m (Fig. l). The species was found at sites with water temperature ranging between 1 1.7 and 245°C, water pH between 6.3 and 8.5, and water dissolved oxygen rang— ing from 3.4 to 12 mg/l (Table 2). At the completion of this study, eight sites in the north, 18 in the centre and 18 in the south of Sardinia were identified as localities currently and/or recently (after 1991) inhabited by the species. A total of four sites in the north, four in the centre and three in the south, constituting 20% of all sites considered, have ap— parently lost the species in the last two decades (Table 3). For a detailed list of all the sites where the presence ofthe species has been assessed in the three years ofre— search or within the last 10 years, see Table 4. DISTRIBUTION IN WESTERN SARDINIA The present distribution study focused particularly on the eastern part of Sardinia, where the presence of E. platycephalus has always been confirmed in the past (Alcher, 1975; Puddu et al., 1988) and which comprises the preferential habitat areas for these salamanders. The species is generally believed not to be present in most of the western areas, or its presence is questioned but not excluded (Alcher, 1975). There are very few records of observations on the west side of the island (forest station workers, pers. comm, Schenk e1 (11., 1995). Neverthe- less, nine localities in the south-west of Sardinia (Table 5) have been visited at least twice over three years of re- 128 R. LECIS AND K. NORRIS TABLE 3. List oflocalities where E. platycephalus was present before 1991 (but where its presence was not confirmed more recently on the basis ofthe forestall station questionnaire) and source ofinformation. Locality Mountain Year of Source system observation Burcei (Rio Brabaisu) Sette Fratelli 1990 Forest stn..obs. Muravera (Rio Picocca) Sette F ratelli 1975 Amphibiaweb Tertenia Ogliastra 1985 Local comm. Benetutti Goceano 1990 Forest. stn. obs. Bolotana Marghine 1990 Local comm. Ala dei Sardi Monti di Ala 1974 Alcher (1975) Siniscola Monti di Ala 1974 Alcher (1975) Nuoro Gennargentu 1974 Alcher (1975) Orgosolo Gennargentu I974 Alcher (1975) Arzana Gennargentu 1974 Alcher (1975) Gairo Ogliastra 1974 Alcher (197 5) search. Salamanders were never observed. Fish pres- ence (Salmo trutta) was recorded in four sites. Combining past information and the results of the present distribution study, salamander presence in the south—west of the island cannot be completely ruled out. Undoubtedly, in these areas E. platycephalus is very rare, and possibly (considering comments and observa- tions by Forestali workers and collaborators) in decline. Another mountainous area located in the north—west of the island, Marghine—Goceano, can also not be ruled out from the salamanders’ range, as it has not been covered by this distribution survey. Few records exist on the past presence ofthe species (Schenk er (1]., 1995). FOREST STATION QUESTIONNAIRE Responses on the presence/absence of the species were received from 60 ofthe 79 forest stations. Forty re— sponses were negative, and 20 were positive. The negative responses contained some reports of the pres- ence of the species in the past but not recently. The positive responses included photographs of salaman- ders, of study sites, and IGM (Istituto Geografico Militare) maps with the actual site where the species was seen indicated. Fig. 2 shows the distribution across Sar- dinia of the 60 Forestali districts that responded. DISTRIBUTION MAPS The general map (Fig. 3) shows the area where the species is present, combining historical and present data. Fig. 4 shows all the localities where species pres- ence has been assessed during the three years of research and in the recent past (since 1991). The sites where it was known to be in the past (before 1991) but where it is no longer present (or at least can no longer be found) are also indicated. This map represents a first attempt to rec- tify the lack of field—based information on E. platycephalus distribution. It therefore provides a framework for further research on Sardinian salamander conservation. DISCUSSION Through a combination of field and questionnaire surveys, conducted between 1999 and 2001, we have attempted to collate information on the present distribu- tion of the endangered endemic Sardinian brook salamander, E. platycephalus. As mentioned in the Re— sults section, a total of 14 localities where Sardinian salamanders are present today have been identified, as well as numerous sites where species presence has been recorded since 1991. A number ofhistorical sites appear no longer inhabited by the species and these should re- ceive particular concern. Conservation efforts should focus on further detailed surveys and habitat protection of salamander-inhabited areas. FIG. 2. Distribution in Sardinia of forestry districts (Uffici Forestali) which replied to the Euproctus platycephalus questionnaire in 2000. DISTRIBUTION OF THE SARDINIAN BROOK SALAMANDER 129 TABLE 4. List of sites where E. platycephalus presence was confirmed by the authors between 1999 and 2001 (top), and (bottom): by forestry workers or local collaborators (Source) after 1991. Italics indicate sites visited by the authors in 2001 where newt presence was not confirmed on the day of survey. Site Mountain Year of Notes system observation Rio S. Mannu Sette Fratelli 1999 One individual Rio Pressiu Sette Fratelli 1999 One individual Rio Gattu Sette Fratelli 1999,2000, 2001 High density Rio Guventu Sette Fratelli 2000, 2001 High density Rio Melliana Sette Fratelli 2000, 2001 Adults and larvae Rio Angiulus Sette Fratelli 2000,2001 Adults and larvae Rio Su Zurru Gerrei 2000, 2001 Adults and larvae Is Angurtidorgiu Quirra 2000, 2001 Hypogeous pop. Roa Paolinu Gennargentu 1999, 2000, 2001 High but declindens. Rio Lardai Gennargentu 2000, 2001 Adults and larvae Funtana Urpis Gennargentu 2000, 2001 One individual Pischina Supramonte 1999, 2000, 2001 High density Rio Pisciaroni Limbara 1999, 2000, 2001 High density Loc. Letto di Fica Gallura 1999 One larva Site Mountain Year of Source system observation Rio Acquacallenti Sette Fratelli 1999 Forestali Q. Rio Baccusafigu Sette Fratelli 1999 Forestali Q. Rio Staulu Mannu Sette Fratelli 1999 Forestali Q. Rio Pireddu Parteolla—Gerrei 1998 Forestali Q. Rio Baccu OmIai Quirra 1999 Forestali Q. Rio Semida Quirra 1999 Forestali Q. Rio Piras Quirra 1993 F orestali Q. Rio Bauporcus Marganai 1998 Forestali Q. Rio Maurreddu Sulcis I995 Forestali Q. Rio di Pula Sulcis 1999 Local comm. Rio Ermolinus Gennargentu 1994 Forestali Q. Rio S.Girolamo Gennargentu 1994 Forestali Q Rio Longufresu Gennargentu 1994 Forestali Q. Rio Samunudolgiu Gennargentu 1999 Forestali Q Rio Pitzirimasa Gennargenru 1999 F orestali Q. Rio Panargia Gennargentu 1997 Forestali Q. Rio Conca Sarui Gennargentu 2000 Forestali Q. Rio Mannu Gennargentu 1995 Forestali Q1 Rio Araxisi Gennargentu 1995 Forestali...
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