Assessing Translocation of Whiptail
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MSc Conservation Science ‘Assessing the Translocation of the St Lucia Whiptail Lizard Cnemidophorus vanzoi: A Retrospective Analysis of Abundance, Demographics and Habitat Utilization’ Heidi Brown A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science and the Diploma of Imperial College London Abstract The St. Lucia whiptail lizard C. vanzoi is a ground dwelling, diurnal, primarily insectivorous macroteiid and a small island endemic. Originally it was only found on two islands (Maria Major and Maria Minor) off the coast of St. Lucia, West Indies. In 1995 due to perceived risk from the mainland a small population was translocated to the smaller uninhabited island of Praslin on the same coastline. In accordance with critics’ views on the long term monitoring of translocated populations, I studied the abundance, demography, morphometrics and habitat utilization of the translocated lizard population over a 3 month period, 13 years post release. Not only was I analysing data collected in this study but also the data collected from previous monitoring studies in a time series analysis, in order to identify how the population has faired since the original translocation. Age, sex, snout-vent length (SVL), body mass (BM) and overall condition (moulting, gravid, cuts, parasites) of 100 lizards caught during the study were analysed and compared with the previous data. Body Condition (CI (BM/SVL)), age ratio (adult: juvenile), sex ratio (male: female) were also calculated and compared under the time series analysis. Distance sampling and mark re-sight surveys were used, calculating a mean abundance of 183 (95% CI: 132 – 279). Habitat utilisation was tested to identify if lizards select habitat randomly and also split by age and sex group. Overall since the translocation took place there appears to be no significant change in abundance, sex ratio, BM and CI. However the age ratio has changed, the number of juveniles to males had decreased suggesting there were problems potentially with juvenile mortality but this threat appears to have now passed. Juvenile mortality could also explain the significant decrease in adult female SVL and this should continue to be monitored. Lizards appear to select habitat non-randomly, choosing areas that help regulate thermoregulation. Overall, the study suggests that the population has successfully colonised Praslin Island, producing a self sustaining viable population. 1 TABLE OF CONTENTS Abstract……………………………………………………………………… ……..1 Contents………………………………………………………………...…….……..2 List of tables……………………………………………………………….….……..3 List of figures………………………………………………………………….…….4 List of appendices…………………………………………………………..….……5 1. INTRODUCTION…………………………..………………..……….6 1.1 This study………………………………………………………………….7 1.2 Objectives …………………………………………………………………9 2. BACKGROUND……………………………………………………………… 10 2.1 Assessment of translocation………………………………………………. 10 2.2 Small island reserves in translocations …………………………………….14 2.3 Translocation of St. Lucia whiptail lizards (Cnemidophorus vanzoi)…….. 15 3. METHODS……………………………………………………………………..18 3.1 Study species………………………………………………………………...18 3.2 Study site…………………………………………………………………….19 3.3 Abundance estimates………………………………………………………...20 3.4 Morphometry and demography……………………………………………...22 3.5 Habitat utilisation……………………………………………………………23 3.6 Statistical analysis…………………………………………………………...24 4. RESULTS………………………………………………………………………26 4.1 Abundance estimates………………………………………………………...26 4.2 Population trends…………………………………………………………….27 4.3 Demographics and dimorphismn…………………………………………….28 4.4 Morphometrics………………………………………………………………29 4.5 Morphometrics and habitat selection………………………………………..32 4.6 General habitat selection…………………………………………………….32 4.7 Body Condition……………………………………………………………...33 5. DISCUSSION…………………………………………………………………..35 6. ACKNOWLEDGEMENTS……………………………………………………41 7. REFERENCES………………………………………………………………....42 8. APPENDICES………………………………………………………………….47 2 LIST OF TABLES Table 1 Description of microhabitat variables for C.vanzoi on Praslin Island…….24 Table 2 Table identifying abundance estimate provided by Distance 5.0…………24 Table 3 Table identifying abundance estimate provided by PETERESEN………..26 3 LIST OF FIGURES Figure 1 Illistration of male and female C.vanzoi on Praslin Island……………….18 Figure 2 Map of St Lucia showing position of Praslin Island………………………20 Figure 3 Map of Praslin Island showing Transects and habitat type……………….21 Figure 4 Grapgh showing C.vanzoi abundance 1999 – 2008………………………27 Figure 4 Graph showing age and sex ratios of C.vanzoi 1999 – 2008………………28 Figure 5 Graph showing presence of Adult Clouration of male C.vanzoi 2008……30 Figure 6 Graph showing decrease in mean SVL for adult female C.vanzoi 1999 – 2008…………………………………………………………………………………..31 Figure 7 Graph showing CI for C.vanzoi 1999 – 2008 …………………………….33 Figure 8 Graph showing Mean CI pooled with abundance for C.vanzoi 1999 – 2008 ………………………………………………………………………………….34 4 LIST OF APPENDICES APPENDIX A: Distance 5.0 Outputs…………………………………………..47 Figure A1: Example of models run in distance…………………………………...47 Figure A2: Output for model used in this study………………………………….47 Figure A3: Graph showing detection probability for this study………………….48 APPENDIX B: Identifying unknown males of 2002…………………………...49 Figure B1: Graph identifying Unknown males of 2002…………………………..49 APPENDIX C: Statistical outputs from R used in this study………………….50 5 1. Introduction Biodiversity is the very basis for the survival of all living organisms on earth, encompassing all life forms, ecosystems and ecological processes, acknowledging the hierarchies at genetic, taxon and ecosystem levels. Estimates of the total number of species on earth vary from 5 – 50 million; though 13.6 million is a more conservative figure (McNeely et al, 1990). However research has indicated that we are entering into a new phase of mass extinction (Myers, 1990). While previous extinctions have happened over millions of years the current mass extinction could well occur within a short period of time; within 200 years. Current scenarios predict a 20% loss of all species within the next 30 years and 50% or more by the end or the 21st century (Singh, 2002). Conservation projects have become common place in the world, striving to preserve Biodiversity and halt continuing declines. Conservation scientists have thus been attempting to incorporate a wide range of management techniques to reduce this decline in Biodiversity. In the face of this global biodiversity crisis translocation has become an important conservation technique. Translocation is defined as the intentional release of animals to the wild to establish, re-establish, or augment a population (IUCN, 1987). Species translocations can form a valuable part of a species recovery programme, which is aimed mainly at reversing historical declines or increasing limited ranges sizes in the status of species of conservation significance. However, the role of translocations in conserving species is a matter of debate, with a range of views within the statutory conservation agencies (and elsewhere) on when and where such activities are acceptable and desirable. Although species translocation has become a popular tool, several previous studies have suggested that many relocations are not successful and fail to achieve self sustaining populations (Grittith et al, 1989; Dodd and Seigel, 1991; lindburg, 1992; Wolf et al, 1996; Fischer et al, 2000) and thus have given rise to increased scientific speculation as to what factors influence the success or failure of translocations. 6 Like so many other conservation practices, translocations are often ad–hoc decisions made in crisis situations, without clear defined objectives, methodologies, measures of success and long term follow up studies, which are all indications of a project that is likely to fail (Dodd and Seigel, 1991). A recent survey carried out by Fischer et al (2000) on the assessment of animal relocations found that only 26% of reintroductions could be classified as a complete success. However this number is likely to be over estimated due to the study only being carried out on published results and often projects will only publish their results if they have been successful. Despite countless articles highlighting problems concerning species translocations and how they can be addressed (Dodd and Seigel, 1991; Fischer et al, 2000); and regardless of the many variables which influence the success of a translocation not all translocation programmes evaluate those factors, nor are they carefully monitored (Cabezas et al, 2007). To ensure that any translocation efforts are going to be as successful as they can be, it is essential they follow through with the recommendations. One of the main recommendations, which relates to this study, is the long term monitoring of the species once it has been translocated (Dodd and Seigel, 1991; Fischer et al, 2000). Monitoring should be carried out on a long term basis because success can take a long time to confirm, especially if a species has a slow reproductive life history. A lot of studies have failed to follow a strict population monitoring scheme (Fisher et al, 2000), and it has been suggested that wildlife managers should develop long term monitoring protocols in which key parameters that can reflect success are carried out at specified time intervals. These parameters can be abundance, sex and age ratios to name but a few. Secondly is the importance of sharing information about translocations (Fischer et al, 2000)