REQUESTED REPORTS Requested Reports 1. BORR IPT (2020) BORR Project Pavement Design and Geotechnical Interpretive Report (BORR‐00‐RP‐ GT‐0004‐February 2020), Unpublished report for Main Roads Western Australia. 2. BORR IPT (2020) BORR Project Factual Geotechnical Investigation Report (BORR‐00‐RP‐GT‐0003‐ February 2020), Unpublished report for Main Roads Western Australia. 3. BORR IPT (2020) BORR Southern Section Overarching Acid Sulfate Soil and Dewatering Management Plan (BORR‐02‐RP‐EN‐0018‐May 2020), Unpublished report for Main Roads Western Australia 4. McDonald, E.M and Phillips, T.E. (2020) Addendum to Report of an Ethnographic Survey of Bunbury Outer Ring Road Southern Section, Gelorup, Western Australia 5. Biota. (2020). Western Ringtail Possum Pseudocheirus occidentalis Regional Surveys. May 2020. Final Report for Main Roads Western Australia. 6. BORR IPT (2018) Preliminary Wetland Assessment APPENDIX B REQUESTED REPORTS B5 Requested Reports Biota. (2020). Western Ringtail Possum Pseudocheirus occidentalis Regional Surveys. May 2020. Final Report for Main Roads Western Australia Western Ringtail Possum Pseudocheirus occidentalis Regional Surveys Main Roads Western Australia May 2020 Western Ringtail Possum Regional Survey © Biota Environmental Sciences Pty Ltd 2020 ABN 49 092 687 119 Level 1, 228 Carr Place Leederville Western Australia 6007 Ph: (08) 9328 1900 Fax: (08) 9328 6138 Project No.: 1407b Prepared by: Roy Teale, Joanne Potts Document Quality Checking History Version: Rev 0 Peer review: Peter Kendrick Ric How Rev 0 Director review: Garth Humphreys Rev 0 Format review: Garth Humphreys Approved for issue: Roy Teale This document has been prepared to the requirements of the client identified on the cover page and no representation is made to any third party. It may be cited for the purposes of scientific research or other fair use, but it may not be reproduced or distributed to any third party by any physical or electronic means without the express permission of the client for whom it was prepared or Biota Environmental Sciences Pty Ltd. This report has been designed for double-sided printing. Hard copies supplied by Biota are printed on recycled paper. /Volumes/Cube/Current/1407e (WRP Regional Additional Sites)/Documents/Western Ringtail Possum Survey Rev 0.docx 3 Western Ringtail Possum Regional Survey 4 /Volumes/Cube/Current/1407e (WRP Regional Additional Sites)/Documents/Western Ringtail Possum Survey Rev 0.docx Western Ringtail Possum Regional Survey Western Ringtail Possum Regional Survey Contents 1.0 Summary 9 2.0 Introduction 11 2.1 Report Structure 11 2.2 Conservation Status of the Western Ringtail Possum 12 2.3 Alignment with the Western Ringtail Possum Recovery Plan 12 2.4 Synopsis of Distance Sampling 15 2.5 Stakeholder Engagement 18 3.0 Methods 19 3.1 Field Sampling Methods 19 3.2 Study Regions 19 3.3 Analyses 30 4.0 Results 33 4.1 Summary Statistics 33 4.2 Distance Sampling Analyses 36 4.3 Density Surface Modelling 47 5.0 Discussion 51 6.0 References 57 Tables Table 2.1: Knowledge gaps for Western Ringtail Possums identified in the Department of Parks and Wildlife (2017) Recovery Plan and mitigation of these incorporated into the design of this study. 14 Table 2.2: Recovery objectives for Department of Parks and Wildlife (2017) Western Ringtail Possums Recovery Plan and outputs from this study. 14 Table 3.1: Study sites at which distance sampling for Western Ringtail Possum was undertaken on the Southern Swan Coastal Plain. 21 Table 3.2: Additional study sites at which recent (2018 and 2019) distance sampling has been completed in the Southern Swan Coastal Plain (as part of Main Roads Western Australia project work) and for which results are included in this document. 22 Table 3.3: Study sites at which distance sampling was undertaken between Dardanup and Crooked Brook. 22 Table 3.4: Study sites at which distance sampling was undertaken in the Cape to Cape region. 23 Table 3.5: Study sites at which distance sampling was undertaken in the Warren management zone. 23 Table 3.6: Study sites at which distance sampling for Western Ringtail Possum was undertaken in the Around Albany subpopulation. 27 Table 3.7: Additional study sites at which recent (2018 and 2019) distance sampling has been completed in the Around Albany area (as part of Main Roads Western Australia project workˇ or on behalf of the Shire of Albany*) and for which results are included in this document. 27 /Volumes/Cube/Current/1407e (WRP Regional Additional Sites)/Documents/Western Ringtail Possum Survey Rev 0.docx 5 Western Ringtail Possum Regional Survey Table 4.1: Key summary statistics for Western Ringtail Possum detections in Swan Coastal Plain Region study sites (raw data). 34 Table 4.2: Key summary statistics for Western Ringtail Possum detections in the Dardanup and Crooked Brook study sites (raw data). 34 Table 4.3: Key summary statistics for Western Ringtail Possum detections in the Cape to Cape study sites (raw data). 35 Table 4.4: Key summary statistics for Western Ringtail Possum detections in the Upper Warren, Dingup, Faunadale, Jardee and Linfarne study sites (raw data). 35 Table 4.5: Key summary statistics for Western Ringtail Possum detections in the Around Albany study sites (raw data). 36 Table 4.6: Key summary statistics for Western Ringtail Possum detections in the Frankland study area (raw data). 36 Table 4.7. AIC scores for each model fitted to the pooled Western Ringtail Possum data excluding sites with fewer than 6 detections. 38 Table 4.8. AIC scores for each model fitted to the pooled Western Ringtail Possum data excluding sites with fewer than 6 detections and the Upper Warren. 38 Table 4.9. AIC scores for each model fitted to the pooled Western Ringtail Possum data including all study sites except the Upper Warren. 39 Table 4.10. Summary of detected clusters within the pooled study sites (except the Upper Warren) (truncation at 25 m). 41 Table 4.11. Summary of detected individuals within pooled study sites except the Upper Warren (truncation at 25 m). 42 Table 4.12. Summary of estimated density of Western Ringtail Possum individuals within each of the study sites (except the Upper Warren). 44 Table 4.13. Summary of estimated abundance of Western Ringtail Possum individuals within the study sites (except Upper Warren). 45 Table 4.14: AIC scores for each model fitted to the Upper Warren Western Ringtail Possum data. 46 Table 4.15. Summary of detected clusters within the Upper Warren (truncation at 55 m). 46 Table 4.16. Summary of detected individuals within the Upper Warren (truncation at 55 m). 46 Table 4.17. Summary of estimated density of Western Ringtail Possum individuals within the Upper Warren. 47 Table 4.18. Summary of estimated abundance of Western Ringtail Possum individuals within the Upper Warren. 47 Table 4.19. Model deviances. 47 Table 5.1. Sampling methods available to document Western Ringtail Possum populations. 53 Figures Figure 2.1. (A) a strip transect sampling example, where all animals along the transect out to distance w are detected (black dots). (B) a transect sampling example, where only a portion of animals present in the survey region are actually detected (black dots), and some animals are missed (grey dots). (C) a distance sampling example, where the perpendicular distances between the transect line (dark grey line) of all detected animals (black dots) are measured. Some animals may be present in the survey region but not detected (grey dots), and the distances these 6 /Volumes/Cube/Current/1407e (WRP Regional Additional Sites)/Documents/Western Ringtail Possum Survey Rev 0.docx Western Ringtail Possum Regional Survey animals are from the transect line (dotted lines) are unobserved and unknown. 16 Figure 2.2. (A) In distance sampling, the distances between the line transect and detected animals are measured. These can be plotted in a histogram of frequencies (hatched bars). That is, 120 animals were observed within a distance of 0.25w from the transect. Animals that were present in the survey region but not detected are assumed to be uniformly distributed from the line transect, and are shown as grey bars. (B) A ‘line of best fit’ to the distance data, shown in red, whereby as distance increases from the line transect the frequency of observations decreases, whereas the underlying distribution of distances is shown as a solid black line remains constant with increasing distance (a uniform distribution). 17 Figure 3.1: Western Ringtail Possum key management zones and IUCN sub- populations. 20 Figure 3.2: Study sites at which distance sampling surveys for the Western Ringtail Possum were undertaken for the Swan Coastal Plain and adjacent Dardanup and Crooked Brook locality. 24 Figure 3.3: Study sites at which distance sampling surveys for the Western Ringtail Possum were undertaken for the Bunbury Outer Ring Road Project. 25 Figure 3.4: Study sites at which distance sampling surveys for the Western Ringtail Possum were undertaken for the Cape to Cape region. 26 Figure 3.5: Study sites at which distance sampling surveys for the Western Ringtail Possum were undertaken for the Cape to Cape region. 28 Figure 3.6: Study sites at which distance sampling surveys for the Western Ringtail Possum were undertaken for the Around Albany region. 29 Figure 4.1: Histogram of pooled perpendicular distances to detections of Western Ringtail Possums. 37 Figure 4.2. Plot of ‘best-fitting’ model to the pooled Western Ringtail Possum perpendicular distance data. Upper Warren detections represented by upper series of open circles. 38 Figure 4.3. Plot of ‘best-fitting’ model to the pooled (excluding the Upper Warren) Western Ringtail Possum perpendicular distance data. 39 Figure 4.4. Plot of ‘best-fitting’ model to the Upper Warren Western Ringtail Possum perpendicular distance data.