Herpetology Notes, volume 9: 157-162 (2016) (published online on 01 August 2016)

Update on the natural history and conservation status of the Saint Lucia racer, Erythrolamprus ornatus Garman, 1887 (: Dipsadidae)

Robert J. Williams1,*, Toby N. Ross1, Matthew N. Morton1, Jennifer C, Daltry2 and Lenn Isidore2, 3

Abstract. The ground Erythrolamprus ornatus is a dipsadid endemic to Saint Lucia, West Indies; it was first categorized as Endangered on the IUCN Red List in 1996. There have been no sightings of the snake on the main island of Saint Lucia since the 1800s, and although the is believed to have once been common on Saint Lucia prior to the introduction of the small Indian (Herpestes javanicus), by 1936 the species was presumed extinct. In 1973, a single E. ornatus was found on the mongoose free, 9.4 ha (12.3 ha surface area) islet of Maria Major, less than 1 km off the southern tip of Saint Lucia. All subsequent accounts of the species have been from Maria Major alone. Here we report the findings of the first detailed study of the population size, diet, and ecology of the Saint Lucia racer, which took place on Maria Major over 30 days between October 2011 and March 2012. Daylight searches produced a total of 41 snake encounters resulting in capture of 11 individuals. A Capture Mark Recapture (CMR) estimate of population size suggests there are fewer than 50 mature individuals on Maria Major. We therefore propose a revised classification of Critically Endangered. Erythrolamprus ornatus on Maria Major appear to be smaller and less colourful than individuals once described from the main island of Saint Lucia, possibly the effects of a genetic bottleneck in this isolated population.

Keywords. Erythrolamprus ornatus, Saint Lucia, natural history, conservation.

Introduction other predators onto many Lesser Antillean islands is inferred to have been the primary cause of population The 30 endemic of the Lesser Antilles (Eastern declines and extinctions (Henderson, 2004; Powell and Caribbean) are of great conservation interest and concern. Henderson, 2005). Although the distribution of snakes With most species having restricted ranges, this group throughout the region is well documented (Schwartz has proved to be highly prone to island extirpations and and Henderson, 1991; Henderson, 2004; Powell and extinctions (Henderson, 2004; Henderson and Powell, Henderson, 2005), an understanding of the population 2009; Caut and Jowers, 2015). The introduction of status and ecology is lacking for many species, the small Asian mongoose (Herpestes javanicus) and particularly those that are very rare and in need of conservation management (with the notable exception of antiguae, see Daltry et al., 2001). Due to limited data from very few documented captures, little is known of the ecology and population 1 Durrell Wildlife Conservation Trust, c/o Forests and Lands status of the Saint Lucia racer (Erythrolamprus ornatus; Resources Department, Gabriel Charles Forestry Complex, Fig. 1). In his early notes on the snakes of Saint Lucia, Union, Castries, Saint Lucia, West Indies Tyler (1850) described the ‘couresse’ as a small snake 2 Fauna & Flora International, The David Attenborough of 2.5–3 feet [76–91 cm] in length, which was the first Building, Pembroke Street, Cambridge CB2 3QZ, United literature reference to E. ornatus. Although no mention Kingdom 3 Forests and Lands Resources Department, Gabriel Charles was given of its distribution, Tyler (1850) recorded Forestry Complex, Union, Castries, Saint Lucia, West Indies that the couresse was the second-most common of the * Corresponding author. E-mail: [email protected] five extant snake species on Saint Lucia at that time, 158 Robert J. Williams et al.

to quantify the population’s size, rate of population change, and threats to the species, application of criteria for a listing as Critically Endangered was not justified (Richard Gibson, pers. comm.). The need to review the conservation status of the Saint Lucia racer was recognized by Daltry (2009) and Morton (2009), whose appraisal of the threats faced by this precarious, isolated population included invasive predators, climate change, inbreeding depression, and stochastic events. Both authors argued strongly for an updated assessment and a listing as Critically Endangered. The need for a revised assessment of the status of the Saint Lucia racer, Figure 1. The Saint Lucia racer (Erythrolamprus ornatus) and the development of a species action plan, was also Photograph by Toby Ross. identified in the management plan of the Pointe Sable Environmental Protection Area (PSEPA) (Gardner, 2009), the largely marine protected area that includes the Maria islands. Here we report the findings of the first detailed study of the population size and ecology of the Saint Lucia strongly suggesting it was widespread throughout the racer, which took place on Maria Major (13.4327°N, island 19 years prior to the introduction of 60.5553°W) between October 2011 and March 2012. to Saint Lucia (Des Voeux, 1903). The species was believed to be extinct by 1936 (Parker, 1936; Honegger, Materials and Methods 1981), and there have been no recorded sightings on the main island of Saint Lucia since the 1800s. In 1973, We adapted methods from those used to estimate the a single E. ornatus was found on the 9.4 ha (12.3 ha number of Antiguan racers on the offshore islands of surface area) islet of Maria Major, less than 1 km off Antigua (Daltry et al., 2003). We employed daylight the southern tip of Saint Lucia (Geoghegan and Renard, visual searches for snakes amounting to a total of 644 1985). All subsequent observations of the species have man hours over 30 days. Our survey team, consisting been from Maria Major alone (Corke, 1987; Sherriff et of up to six surveyors, repeatedly walked a series of al., 1995; Buley et al.,1997; Morton, 2009).�One other nine trails of varying length (Fig. 3) that facilitated snake species is known to occur on Maria Major, the unhindered movement throughout the island (most diminutive Saint Lucia threadsnake (Tetracheilostoma breuili) (Daltry, 2009). There is limited information available on the diet of E. ornatus, apart from the second-hand sighting reported in Sherriff et al. (1995) of an individual eating an adult Saint Lucia anole (Anolis luciae). Tyler (1850) listed , anurans, mice, and other small as the prey taken when the snake was prevalent on the Saint Lucia mainland. In the absence of mammals and amphibians on Maria Major, A. luciae, and the Saint Lucia whiptail (Cnemidophorus vanzoi), were suggested to be the main prey items (Corke, 1987; Sherriff et al., 1995; Henderson, 2004; Morton, 2009). The Saint Lucia racer population was evaluated and listed as Endangered by Gibson (1996). It seems the assessor considered that the entire world population, found only on the 12 ha, mongoose- and rat-free, nature reserve of Maria Major (Fig. 2), comprised no Figure 2. Maria Major Island (foreground), Saint Lucia, West more than 250 mature individuals. With a lack of data Indies. Photograph by Toby Ross. Update on the natural history and conservation status of the Saint Lucia racer 159

diet, each captured individual’s intestinal tract was gently palpated to attempt to extract a faecal sample to examine for the presence of prey remains. Capture-mark-recapture (CMR) data were analysed using Begon’s weighted mean estimator (Begon, 1979) to estimate the number of adults and subadults in the population after determining that all assumptions of the model had probably been met (e.g., the island population is geographically closed and not subject to immigration or emigration, demographically closed for the duration of the study with no presumed deaths and no juveniles included in the estimate, and that all individuals are equally likely to be caught; Daltry et al., 2001). Because previously caught animals can remain at the point of release for some time and become biased to recapture (Daltry et al., 2012), we also excluded snakes caught less than 48 h since previous capture from the estimate.

Results Actively searching for snakes during daylight hours produced a total of 41 snake encounters, 16 of which were captured. Of the 16 captures, five were recaptures, Figure 3. Maria Major Island with survey trails detailed to thus a total of 11 individuals were captured. One of indicate areas searched. these recaptures was omitted from the population size analysis below because it occurred less than 48 hrs after initial capture. The mean encounter rate for the survey team was 41 in 301 h (0.14 snakes/h), and the mean encounter rate for each member of the survey team was 41 in 644 h (0.06 snakes/man-hour). of the trails were created in advance of the study, to When applied to our CMR data, Begon’s weighted facilitate access to areas that were previously difficult mean method estimated a population size of 17.8 to reach). All trails were surveyed multiple times over adult and subadults, with a standard error of ± 9.94. the course of each survey day (0800–1700 h). Attempts As we made only three recaptures (one individual was were made to capture by hand all snakes encountered. recaptured on two occasions), this estimate should be Upon capture, snakes were sexed and measurements treated with caution. made of snout–vent length (SVL), tail length, and total Morphometric measurements and scale counts were length (TL) using string, as well as head length and head recorded from 11 individual Saint Lucia racers (Table width using dial callipers following methods outlined 1). The largest of the 11 individuals captured had a in Daltry (2002). Counts of ventral and subcaudal total body length of 775 mm. The mass of the captured scales were also made. Total mass was measured with a individuals ranged from 21–76 g. precision spring balance (Pesola®) accurate to 1 g. A 14- We observed Anolis luciae being consumed by mm Passive Integrated Transponder (PIT) tag (Trovan® a released racer, and a partially digested A. luciae system) was injected subcutaneously in the left flank, ~3 was regurgitated by a racer prior to being caught. cm anterior to the vent, of each racer captured (with the Skeletal fragments from a Maria Islands dwarf gecko exception of one individual of < 450 mm SVL, which (Sphaerodactylus microlepis thomasi) were found in the was considered too small to tag). Tapering of the tail single faecal sample collected from a captured racer. We below the vent was the primary method for identifying did not record evidence of C. vanzoi being preyed upon, female snakes, otherwise cloacal probe depth was used although this is based on a very small sample. to sex the specimens (male racers probed to depths of 14–27 mm, females 3–5 mm). To analyze the racer’s Robert J. Williams et al. 160 300 Table 1. Average scale counts and measurements taken on Saint Lucia racers

Table 1. Average301 scale(Erythrolamprus counts and measurements ornatus). The taken number on Saint of Luciaindividuals racers ( (nErythrolamprus) is provided along ornatus with). the The number of individuals (n) is provided along with the mean ± standard deviation and the size range. 302 mean ± standard deviation and the size range.

Sex Male Female Unknown (n = 5) (n = 5) (n = 1) Ventral scale count 188 ± 3 191 ± 3 192 (184–192) (188–193) Sub-caudal scale count 86 ± 1 87 ± 1 85 (83–87) (86–88) Snout-vent length (mm) 477 ± 24 527 ± 49 443 (450–520) (468–583) Tail length (mm) 168 ± 13 176 ± 17 125 (160–196) (155–192) Total length (mm) 646 ± 36 703 ± 66 568 (610–716) (623–775) Head length (mm) 16.5 ± 0.9 17.7 ± 1.4 14 (15.2–17.6) (16.0–19.0) Head width (mm) 10.3 ± 0.6 10.9 ± 0.9 9.4 (9.3–11.0) (10.0–12.0) Mass (g) 46.6 ± 12 62 ± 15 21 (36–70) (41–76) 303 304 305 Figure 1. The Saint Lucia racer (Erythrolamprus ornatus) Photograph by Toby Ross. 306

Discussion 307 Figure 2. Maria Major Island (foreground), Saint1980). Lucia, Our West estimate Indies. of Photograph fewer than by 50 mature individuals 308 Toby Ross. means the Saint Lucia racer meets the population size Employing visual searches while walking along a 309 criterion D for being classified as Critically Endangered trail network covering as much of the island as possible (IUCN, 2001). We are unable to draw inferences about has proved to310 be theFigure most 3 . effectiveMaria Major method Island to with date survey for trails detailed to indicate areas searched. recent population trends due to the very limited data detecting the311 Saint Lucia racer. Four studies conducted collected in recent decades. since the 1970s managed to capture between only one and two individual Saint Lucia racers each. Dixon We found what appeared to be striking discrepancies (1981), Corke (1987), and Buley et al. (1997) each in body size between our sample from Maria Major and found only a single individual, and two individuals were the Saint Lucia racers reported in the literature. Dixon seen by Sheriff et al. (1995). Having experienced a total (1981) reported a maximum female total length of 1631 of 41 snake encounters, with 16 captures, demonstrates mm, and maximum male total length of 762 mm, which how productive the search methods used during our are both considerably larger measurements than the study were, and provides an encouraging foundation largest female (775 mm) and largest male (716 mm) for future efforts. Buley et al. (1997) were the only from this study. Only one of our individuals was within authors who provided data on search effort, and their the range given by Tyler (1850) of snakes of around team encounter rate of 0.009 snakes/h was considerably 2½ feet (~760 mm) to 3 feet (~915 mm) in length. It is lower than our team encounter rate of 0.14 snakes/h. possible that racers on Maria Major are failing to live While we believe even more intensive research is (and hence grow) as long as their mainland counterparts, required to achieve a more reliable population estimate, or possibly have reduced growth rates due to some other the estimate we produced using CMR strongly suggests factor unknown at this time. Another possibility is that the Saint Lucia racer population is very small, with the small sample size of this survey does not reflect the likely fewer than 50 mature individuals. This low entire size variation present within the current Maria number is credible because Maria Major is likely Major population. However, previous captures from suboptimal habitat for E. ornatus: the islet is small, Maria Major, have also yielded rather small snakes, of xeric and drought-prone, and members of the genus 735 mm TL (Corke, 1987), 610 mm and 667 mm TL Erythrolamprus (previously classified as Liophis) are (Sherriff et al.,1995). Only the capture of an 811 mm typically associated with more mesic habitats (Dixon, female by Buley et al. (1997) suggest larger individuals Update on the natural history and conservation status of the Saint Lucia racer 161 may be present on the islet, and even that size is only provided training in racer survey techniques on Antigua’s offshore roughly half of the maximum length for females islands. Special acknowledgement goes to those who assisted in reported by Dixon (1981). the field: Stephen Lesmond, Mathurin James, Julius Georges, Alex Blackman, Kate Entwistle, Alex Fleming, and Lucy Body size is not the only difference between the Williams. Jolien Harmsen and staff at The Reef gave support in population on Maria Major and the extinct mainland the form of boat transport. Funding for this work was provided by population. The species name ornatus was given by The Balcombe Trust. JD’s participation was supported by Fauna Samuel Garman (1887) to specimens collected from & Flora International and the Disney Conservation Fund. the Saint Lucia mainland in the 19th century because many of them were brightly patterned in yellow and References black. We observed no such brightly marked specimens on Maria Major: all individuals were generally brown, Begon, M. (1979): Investigating Abundance. London, with or without darker markings (see Daltry et al., United Kingdom, Edward Arnold. 2014 for photographs and further details). Perhaps the Buley, K.R., Prior, K.A., Gibson, R.C. (1997): In search of the St. Lucia Racer, Liophis ornatus, with further observations on the absence of the yellow and black variety is the result of fauna of the Maria Islands, St. Lucia, West Indies. Dodo, natural selection, or perhaps this is merely the result of Journal of the Wildlife Preservation Trusts 33: 104–117. genetic erosion in this very small and intuitively inbred Caut, S., Jowers, M. (2015): Is the Martinique ground snake population. Erythrolamprus cursor extinct? Oryx, available from: CJO2015. We collected limited data on the diet of this species, doi:10.1017/S0030605315000228. but confirmed lizards of the genera Anolis and Corke, D. (1987): Reptile conservation on the Maria Islands, St. Sphaerodactylus were eaten. These lizards are very Lucia, West Indies. Biological Conservation 40: 263–279. abundant on Maria Major: rapid surveys in 2011 Daltry, J.C. (2002) Antiguan Racer Census: Guidelines for Fieldworkers. Fauna and Flora International, Caribbean produced estimates of over 20,000 A. luciae and over Programme. 40,000 S. microlepis thomasi on the islet (Ross and Daltry, J.C. (2009): The Status and Management of Saint Lucia’s Williams, 2012). It seems unlikely the racers would Forest and Amphibians. Technical Report No. 2 to prey exclusively on only two species of , however, the National Forest Demarcation and Bio-Physical Resource and we suspect they naturally prey on all lizard species Inventory Project. Helsinki, Finland, FCG International Ltd. encountered on Maria Major, including the globally Daltry, J.C., Bloxam, Q., Cooper, G., Day, M.L., Hartley, J., Henry, threatened whiptail C. vanzoi. M., Lindsay, K., Smith, B.E. (2001): Five years of conserving Our discovery that the E. ornatus population is very the ‘world’s rarest snake’, the Antiguan racer Alsophis antiguae. Oryx 35: 119–27. small is alarming and highlights the urgent need for Daltry, J.C., Morton, M.N., Smith, B.E., Sylvester, I. (2003): 2003 further measures to conserve this species. Drawing Antiguan Racer Census and Re-introduction. Antiguan Racer directly on this study, a 10-year species recovery plan Conservation Project, St John’s, Antigua & Barbuda. (2015–2024) has been developed by national and Daltry, J.C., Hayne, P., Morton, M.N. (2014): Saint Lucia Racer: international agencies. Priority actions include: ensuring Conservation Action Plan, 2015–2024. Report to the Saint Lucia the Maria Major ecosystem remains free from alien Forestry Department, Saint Lucia National Trust, Fauna & Flora vertebrates; establishing a captive breeding programme; International and Durrell Wildlife Conservation Trust. establishing a second population of racers on another des Voeux, G.W. (1903): My Colonial Service In British Guiana, St. Lucia, Trinidad, Fiji, Australia, New-Foundland, and Hong site in Saint Lucia free from invasive alien predators; Kong With Interludes. London, United Kingdom, John Murray. public education; legislation and enforcement; and Dixon, J.R. (1980): The neotropical colubrid snake genus Liophis. further research to increase knowledge of the species’ The genetic concept. Milwaukee Public Museum: Contributions biology, threats, and the impacts of these measures in Biology and Geology 31: 1–40. (Daltry and Morton, 2014). Dixon, J.R. (1981): The neotropical colubrid snake genus Liophis: the Eastern Caribbean complex. Copeia 2: 296–304. Acknowledgements. This work was carried out under the Gardner, L. (2009): Management Plan for the Pointe Sable auspices of the Caribbean Programme of Durrell Wildlife Environmental Protection Area, 2009–2014. Government of Conservation Trust, in partnership with the Saint Lucia Forests Saint Lucia, Castries. and Land Resources Department, Saint Lucia National Trust Garman, S. (1887): On West Indian reptiles in the Museum of and Fauna & Flora International as part of Durrell’s Eastern Comparative Zoology at Cambridge, Mass. Proceedings of the Caribbean Programme. The authors are grateful for the support of American Philosophical Society 24: 278–286. Alwin Dornelly and the Forests and Land Resources Department, Geoghegan, T., Renard, Y. (1985): Maria Islands Nature Reserve. the Saint Lucia National Trust, and Dr. Angelo Pernetta. Andrea Eastern Caribbean Natural Areas Management Programme and Otto of the Offshore Island Conservation Programme in Antigua Saint Lucia National Trust, Saint Lucia. 162 Robert J. Williams et al.

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Accepted by Hinrich Kaiser