National Recovery Plan for the Corangamite Water Skink Eulamprus tympanum marnieae Garry Peterson and Peter Robertson

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National Recovery Plan for the

Corangamite Water Skink

Eulamprus tympanum marnieae
Garry Peterson and Peter Robertson

Prepared by Garry Peterson, Department of Sustainability and Environment, Victoria and Peter Robertson, Wildlife Profiles Pty Ltd.

Published by the Victorian Government Department of Sustainability and Environment (DSE) Melbourne, 2011.

This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.

Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne.

ISBN 978-1-74242-368-5 (online)

This is a Recovery Plan prepared under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, with the assistance of funding provided by the Australian Government. This plan revises that previously produced for the Corangamite Water Skink for the period 1998-2003.

This Recovery Plan has been developed with the involvement and cooperation of a range of stakeholders, but individual stakeholders have not necessarily committed to undertaking specific actions. The attainment of objectives and the provision of funds may be subject to budgetary and other constraints affecting the parties involved. Proposed actions may be subject to modification over the life of the plan due to changes in knowledge.

Disclaimer

This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence that may arise from you relying on any information in this publication.

An electronic version of this document is available on the Department of Sustainability, Environment, Water, Population and Communitieswebsite www.environment.gov.au

For more information contact the DSE Customer Service Centre 136 186

Citation: Peterson, G. and Robertson, P. 2011. Recovery Plan for Corangamite Water Skink Eulamprus tympanum marnieae. Department of Sustainability and Environment, Melbourne.

Cover photograph: Corangamite Water Skink Eulamprus tympanum marnieae, Lake Bolac, Vic, by Peter Robertson, Wildlife Profiles Pty. Ltd.

Contents

summary 4

Species Information 4

Description 4

Taxonomy 5

Distribution 5

Habitat 6

Important Populations 6

DECLINE AND THREATS 7

Recovery INFORMATION 8

Existing Conservation Measures 8

Recovery Objectives 10

Program Implementation and Evaluation 10

Recovery Actions 10

Implementation Cost 10

Table 2: Summary of Recovery Objectives, Performance Criteria and Actions 11

Management Practices 13

Affected Interests 13

Role and Interests of Indigenous People 14

Biodiversity Benefits 14

Social and Economic Impacts 14

ACKNOWLEDGEMENTS 15

REFERENCES 15

Table 3: RECOVERY ACTIONS, costs AND TIMELINES 18

Appendix I: Recovery Objectives and Actions-DETAIL 20

Figure 1. Distribution of Corangamite Water Skink 5

Table 1. Population information for Corangamite Water Skink 6

summary

The Corangamite Water Skink (Eulamprus tympanum marnieae) is endemic to Victoria where it is restricted to the rocky verges of a few wetlands on the Victorian Volcanic Plain. The skink has undergone a decline, disappearing from at least two historical locations, and is known from only 30 sites representing 11 discrete extant populations. Threats such as rock removal, vegetation clearance, inappropriate grazing, wetland loss and inappropriate water management have contributed to its decline and threaten the remaining populations. The Corangamite Water Skink is listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, Threatened under the Victorian Flora and Fauna Guarantee Act 1988, and is considered Critically Endangered in Victoria (DSE 2007). This national Recovery Plan for the Corangamite Water Skink is a revised recovery plan which builds on the previous plan for the subspecies (Robertson 1998), and details its distribution, habitat, threats and recovery objectives and actions necessary to ensure its long-term survival.

Species Information

Description

The Corangamite Water Skink (Eulamprus tympanum marnieae) (Hutchinson and Rawlinson 1995), is a medium-sized lizard of the family Scincidae. Adults grow to 100 mm snout-vent length, with a tail length up to 150 mm and a body mass of up to 25 grams. The dorsal colouration is pale olive to dark yellowish brown overlain by irregular black markings, some forming broken bands across the back and tail. A heavy, irregular, somewhat broken black stripe extends from the snout along the sides to the hind limbs, while the limbs are overlain by heavy black stripes and blotches. The throat varies from greyish-white with black patches to wholly black. Ventral colouration varies from bright yellow to pale greyish yellow, overlain by two thick black longitudinal lines of either small specks, thick patches or bars from the chest to the groin (Hutchinson and Rawlinson 1995).

The Corangamite Water Skink is a diurnally active, basking skink. However, unlike other water skinks, E. t. marnieae is extremely shy, and will often flee and take cover when a human observer is still tens of metres away (Hutchinson and Rawlinson 1995; G. Peterson pers. obs. 1997), taking refuge in deep gaps and fissures in the rock piles. It occupies small defined home ranges (most <10m²) and is territorial (Malone and Peterson in prep). Home range size is influenced by proximity to a waterbody and increases as a function of the distance from the edge of the water-line, indicating that optimal microhabitats are situated close to water (Malone and Peterson in prep).

It is viviparous, producing one clutch per year of 2–7 live young (Peterson 2002). Females first reproduce at two or three years of age, depending on the population (G. Peterson unpubl.data 2009). Once mature, most females breed every year. Litter size and mass increase with female size (Peterson 2002). Juveniles generally occupying separate microhabitats and activity periods from that of adults (Peterson 2002). It is not known whether this is due to agonistic behaviour of adults towards juveniles or specific ecological requirements of juveniles, such as smaller prey items in the microhabitat they occupy. Offspring mortality appears high following birth, while sub-adult and adult survivorship is relatively high (G. Peterson unpubl. data 2009). Subadult survivorship is, however, influenced by population density. Estimated longevity of the Corangamite Water Skink in the field is nine years (G. Peterson unpubl. data 2009), although life expectancy may well be similar to that of E. t. tympanum, up to 15 years (Rohr 1997).

Diet is mainly invertebrates such as spiders, beetles and ants, as well as aquatic prey including mayfly and dragonfly nymphs (Knights 2003). It also consumes the fruit of the Tree Violet (Melicytus dentata), which may be an important component of the diet during some periods (Peterson 1997). The lizard may also play an important role in the dispersal and germination of this plant. The seeds of the introduced African Boxthorn (Lycium ferocissimum) and other unidentified seeds have also been found in scats (Knights 2003).

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