FAUNA SENSITIVE ROAD DESIGN VOLUME 1 PAST AND EXISTING PRACTICES Fauna Sensitive Road Design. Volume 1, Past and Existing Practices First published February 2000. Reprinted 2002. Published by the Queensland Department of Main Roads, Planning, Design and Environment Division. Copyright © The State of Queensland (Department of Main Roads) 2000. Copyright in this document remains with the Queensland Department of Main Roads. It may be reproduced for study, research or training purposes subject to the inclusion of an acknowledgement of the source and no commercial usage or sale. Reproduction for purposes other than those listed above requires the prior written permission of the Executive Director, Planning, Design and Environment Division. Requests and enquiries concerning reproduction and rights should be addressed to the Principal Manager (Environment), Planning, Design and Environment Division, GPO Box 1412, Brisbane, Qld 4001, Australia. Disclaimer: information in this document does not necessarily represent Government policy. While this publication has been prepared with care, the Queensland Government accepts no liability for any decisions or actions taken on the basis of this document. National Library of Australia Cataloguing-in-Publication entry Fauna sensitive road design Bibliography. ISBN 0 7242 9648 (v.1) 1. Roads - Design and construction - Environmental aspects - Australia. 2. Corridors (Ecology) - Australia. 3. Wildlife crossings - Australia. 4 Wildlife conservation - Australia. 5 Roads - Australia Safety measures. 6. Culverts - Australia - Design and construction. I. Queensland Department of Main Roads. Planning, Design and Environment Division. II. Title: Past and existing practices. 625.725 Cite this document as: Queensland Department of Main Roads (2000). Fauna Sensitive Road Design. Volume 1 - Past and Existing Practices. Queensland Department of Main Roads, Planning, Design and Environment Division. Brisbane. Available from: Queensland Department of Main Roads, Planning, Design and Environment Division GPO Box 1412, Brisbane, Qld. 4000. Cover design by Dragon Prints TABLE OF CONTENTS SUMMARY 1 1 INTRODUCTION 4 2 CURRENT LEGISLATION REGARDING FAUNA CONSERVATION 5 3 POPULATION ECOLOGY AND ANIMAL BEHAVIOUR 6 3.1 Theoretical Issues 6 3.2 Behaviour of Animal Species 12 4 WILDLIFE CORRIDORS 16 4.1 Wildlife Corridors as Habitat Linkages 16 4.2 Corridors along Roadsides 18 4.3 Suitability of Vegetated Corridors 19 4.4 Corridor Width 21 5 EFFECTS OF ROADS 22 5.1 Direct Impacts 22 5.2 Indirect Impacts 26 6 EXISTING PRACTICES 29 6.1 Underpasses and Culverts 29 6.2 Overpasses 37 6.3 Exclusion or Guide Fencing 38 6.4 Wildlife Reflectors 42 6.5 Warning Signs 43 7 REVIEW OF FIELD DATA 47 7.1 General Description of the Data 48 7.2 Culvert Size and Type 51 7.3 Vegetation Associated with Culverts 55 7.4 Wet or Dry Passage through Culverts 56 7.5 Wildlife Fencing 57 7.6 Summary of Findings 58 8 CONCLUSIONS 60 8.1 Influence of Animal Behaviour on Impacts of Roads 60 8.2 Fauna Use of Existing Structures 61 8.3 Recommendations for Accommodating Fauna 62 8.4 Overview of Present Management Practices 64 8.5 Future Directions and Research 64 9 REFERENCES 66 APPENDICES A Survey Data from Study of Culverts by AMBS Consulting(1997) B Survey Data from Study of Culverts by Kinhill Pty Ltd (1996) Fauna Sensitive Road Design SUMMARY BACKGROUND Clearing practices in Australia have reduced the area of native habitat available to fauna. Transport corridor infrastructure has not only played a part in the clearing of land, but also in habitat fragmentation. As a consequence of these actions, it is becoming increasingly important that we design and manage transport corridors so as to reduce the impact on Australia’s native fauna species. Research to date has confirmed that transport infrastructure (and in particular roads) has both direct and indirect impacts on fauna. Direct impacts such as road mortalities can be significant for fauna populations with low numbers or widely dispersed individuals. In addition, indirect impacts from barriers to fauna movement, such as fences or embankments, and edge effects, created by vegetation clearing, are known to reduce movement and thus reduce breeding opportunities for many species. The increasing recognition of these impacts has led to the trialling and implementation of measures (or modifications) to improve road design. Measures vary from the installation of structures designed specifically to facilitate or guide fauna movement, to signs intended to increase the awareness of motorists. The installation of many measures in the past was largely driven by perceptions of what structures animals would use. In many cases, post-construction monitoring, or the appropriate maintenance of such structures, was not undertaken, and many structures have now been found to be ineffective. The monitoring of existing structures has increased over recent years, and a better understanding of their utility is being developed. IMPORTANCE OF THIS DOCUMENT The Queensland Department of Main Roads has recognised the importance of planning, designing, constructing and maintaining roads in an ecologically sensitive manner. Although there is a large body of work about transport infrastructure effects on fauna, this information has not been compiled into a form that would help practitioners identify the most appropriate and effective measures to adopt. This volume, ‘Fauna Sensitive Road Design—Past and Existing Practices’, is the first in a two-volume series, and is intended to provide an overview of existing knowledge relating to the impact of transport infrastructure on fauna, in addition to discussing the methods available to reduce these impacts. It is intended that the second volume, ‘Fauna Sensitive Road Design—Preferred Practices’, will provide a compilation of trials currently being undertaken by Main Roads and other State and international road management agencies. This latter volume will identify which measures are appropriate for facilitating 1 Fauna Sensitive Road Design the safe movement of fauna. For the purposes of these two volumes, fauna has been divided into fauna groups (e.g. small ground dwelling mammals, large ground dwelling mammals, birds, reptiles, etc). COMPILATION OF DATA WITHIN THIS VOLUME This volume discusses the potential impacts of transport infrastructure on fauna. It includes a brief theoretical background to animal behaviour and the function of vegetated corridors so as to help the reader understand the challenges faced when designing infrastructure that is to accommodate fauna movement. Also included in this volume is a review of practices used in road designs to facilitate fauna movement. Two field studies in particular are analysed, and the general trends in effective designs and modifications noted in these studies are discussed. The studies mainly examine drainage structures and the use of these structures by fauna. A general indication of which culvert type facilitates effective movement for each fauna group is provided (see Table 1). It is, however, important to recognise that the data presented in Table 1 is preliminary only, and this data will be consolidated following further studies currently being undertaken and envisaged for inclusion in Volume 2 of this series. Table 1 Confirmed use of culvert or underpass type by fauna (+ indicates known use, - indicates not known or unconfirmed use) Fauna type Small pipe Large pipe Small box Large box Bridge <0.5 m >0.5 m culvert culvert underpass diameter diameter <1.2 m high >1.2 m high Small mammal + + + + + Medium mammal + + + - + Large mammal - + - + + Semi-arboreal mammal¹ - - - +* +* Arboreal mammal² - - - - - Microchiropteran bats³ - - - + + Reptile - + - + + Bird + - - + + Amphibian + - + + + Introduced predator + + + + + * The only semi-arboreal mammals recorded in fauna tunnels are the Koala and Eastern Pygmy Possum. These species are not considered to be exclusively arboreal. 1 Semi-arboreal mammal is one that spends the majority of time in trees but is also known to travel on the ground (e.g the Koala). 2 Arboreal mammals are tree-dwelling mammals (e.g. the Sugar Glider). 3 Microchiropteran bats are the small, insect-eating bats. 2 Fauna Sensitive Road Design A synopsis of successful measures that facilitate fauna movement is included in Chapter 8 of Volume 1. Key findings include: • Culverts of a size appropriate for the safe passage of numerous fauna types, rather than just one or a few fauna types, should be installed. • The provision of dry passage within underpasses or culverts is preferable. Multiple cell culverts with the outer cells raised, or raised ledges within a culvert, will greatly assist fauna movement. • Revegetation using locally indigenous plant species is suggested for the entrances of culverts. This provides an extension of habitat nearer to culvert entrances and thus provides shelter for fauna entering and exiting culverts. • Wildlife fencing associated with culverts has proven to be effective in guiding animals into culverts and reducing road deaths. Fences installed on one side of the road only have not been found to reduce fauna road-kills. • Ongoing maintenance of fences is essential to maintain their effectiveness. In particular, Koala- proof fences (unlike wildlife fences) require maintenance so that trees do not grow within 3 m of the fence. This ensures that Koalas do not climb the trees and jump the fence. FUTURE RESEARCH The final section of this volume identifies those areas that require research so