Tasmanian Bird Report 38 July 2017 BirdLife Tasmania, a branch of BirdLife Australia Editor, Wynne Webber TASMANIA The Tasmanian Bird Report is published by BirdLife Tasmania, a regional branch of BirdLife Australia Number 38 © 2017 BirdLife Tasmania, GPO Box 68, Hobart, Tasmania, Australia 7001 ISSN 0156-4935 This publication is copyright. All rights reserved. No part of this publication may, except for the purposes of study or research, be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of BirdLife Tasmania or the respective paper’s author(s). Acknowledgments NRM South, through funding from the Australian Government’s National Landcare Programme, has provided financial assistance for the publication of this report. We thank them both for this contribution. Contents Editorial iv Wynne Webber State of Tasmania’s terrestrial birds 2014–15 1 Mike Newman, Nick Ramshaw, Sue Drake, Eric Woehler, Andrew Walter and Wynne Webber Risk of anticoagulant rodenticides to Tasmanian raptors 17 Nick Mooney Oddities of behaviour and occurrence 26 Compiler, Wynne Webber When is the best time to survey shorebirds? 31 Stephen Walsh A Eurasian Coot nests in Hobart 32 William E. Davis, Jr Changes in bird populations on Mt Wellington over a 40-year period 34 Mike Newman 2016 Summer and winter wader counts 44 (incorporating corrected tables for 2015 summer counts) Eric Woehler and Sue Drake Editorial In this Tasmanian Bird Report we institute what is hoped to be a useful and ongoing enterprise, which replaces the systematic lists of earlier years: a report on ‘The state of Tasmania’s birds’. In this edition, the report focuses on terrestrial birds, and it has been a time- consuming undertaking by Mike Newman and Nick Ramshaw in particular, although the final was put together by a subcommittee of BirdLife Tasmania. To make regular reports that track populations of the State’s birds, reliable population records are needed. Anyone who can begin surveys of their home area or of a favourite birdwatching haunt can participate through Birdata (http://birdata.birdlife.org.au/) where new data is entered and feedback is given. Nick Mooney has contributed an important paper on the dangers of anticoagulant rodenticides. It will, if advertised widely, help inform the community on the best methods for eliminating pests while helping to protect vulnerable raptors. Several useful and interesting notes have been contributed by Stephen Walsh and William (Ted) Davis and a short article on oddities of behaviour and occurrence has been compiled from members’ contributions. Such material is sought for future editions. Mike Newman rounds out the papers with a review of Mt Wellington’s bird populations at several survey sites over a forty-year span, and the tables of summer and winter wader counts complete the Tasmanian Bird Report 38. The Bird Report is a vehicle for publication of papers by researchers and amateur bird- watchers from around the State, as well as for releasing reports that have been completed for various interests: governmental, NGO and commercial. We strongly encourage members and researchers to submit papers. Wynne Webber Editor Tasmanian Bird Report State of Tasmania’s terrestrial birds 2014–15 Mike Newman, Nick Ramshaw, Sue Drake, Eric Woehler, Andrew Walter and Wynne Webber, a subcommittee of BirdLife Tasmania Introduc)on July 2014 to June 2015. Financial year reporting has the The initial Tasmanian Bird Report (Newman 1971) gave an advantage of encompassing a single breeding season for annual review of birds based on the systematic species most species. The lag of at least a year between data list for the State. Subsequently, the report expanded its collection and publication of the annual review ensures role, publishing papers and summaries of the results of that the data set is comprehensive because there are ongoing scientific studies, including the shorebird and often delays in receiving observations. gull counts. Expansion of the size of the Tasmanian sys- This report uses the current BirdLife Australia list of tematic list and increased numbers of contributors and species: the Working List of Australian Birds v2 (2016). their observations greatly magnified the complexity of Survey methods maintaining a systematic list database and producing a Surveys are mostly undertaken by volunteers and so succinct, meaningful report. As a consequence, a sys- survey-site selection is based on personal preference. tematic list was last published in 2006 in Tasmanian Bird The distribution of survey sites for 2014–15 is shown in Report 32. figure 1 (page 8). While attempts are made to achieve In 1971 observations that were deemed important representative habitat and geographical coverage, this is (unusual) were recorded on a card index from which the not optimised. Most observations submitted to the systematic list was compiled. Over the subsequent 45 Birdata portal involve four types of surveys: years, continual advances in electronic data storage and processing have transformed our ability to evaluate and 2 ha/20 minute surveys: This is BLA’s preferred summarise increasingly large data sets. survey type because it involves standardised survey The recent launch of an enhanced BirdLife Australia effort, which is the most reliable information for trend portal, Birdata, has provided access to summary data for analysis (Ehmke et al. 2015). the Tasmanian region. This report is a first step in 500 m area surveys: These surveys involve a larger reinvigorating an annual review of Tasmania’s birds, area and variable duration. They generate longer with the focus being on terrestrial birds that regularly species lists and are used for trend analysis for scarce breed or visit Tasmania, and it thus builds on the com- species when 2 ha surveys contain insufficient records. prehensive overview first provided by Ridpath and 5 km area surveys: Observer effort in these surveys is Moreau (1965). extremely variable, which compromises their use for After the completion of the second national bird atlas trend analysis. (1998–2001, The New Atlas of Australian Birds, Barrett et Incidental records: These are used to record unusual al. 2003), ongoing collection of Atlas information placed observations where a complete survey is not conducted. increasing emphasis on monitoring changes in the status This type of information is not used in trend analysis. of bird populations as well as changes in distribution. Accordingly, this report places increased emphasis on Methods the statistics of common species. As well as summary Comparison of reporting rates (RRs) — the percentage data, the report includes three case studies that discuss frequency with which a species is recorded — provides a aspects of the status of several bird species in Tasmania. more reliable basis for annual comparisons than It is envisaged that future Bird Reports will discuss numbers of observations, particularly when the survey different aspects of Tasmania’s birds as identified in method is standardised. If a species has a RR of 50% reviews of Birdata or from conservation concerns. for 500 m area surveys, it indicates the species is It has been decided to report against financial year common and an observer has a good chance (1:2) of periods, with this initial report covering the year from seeing that species within about one hour in an area of 1 500 m radius. Correspondingly, if a species has RR of recorded species, which included two endemic and two 1% or less for 2 ha/20 minute surveys it is either rare or introduced species. The widely distributed and easily difficult to observe. The chances of detecting it are low detected Forest Raven, Corvus tasmanicus, was most (1 in 100 or less), unless its specific habitat is selected or recorded with 1685 records compared with an average there is prior knowledge of its occurrence at a location. of 802 in the previous ten years. The higher number of The background to the method used for trend analysis records in 2014–15 probably reflects an increase in the is provided in Cunningham and Olsen (2009). submission of records to Birdata (see table 1) rather than a change in the status of the species. For all Survey stascs frequently recorded species the number of records in The survey effort in 2014–15 involved 3017 surveys, 2014–15 was typically two times greater than the which was more than double the average number for previous ten-year average. The diminutive Superb the previous ten years (table 1). In all, 191 bird species Fairy-wren, Malurus cyaneus, was the second most were recorded. The reason for the increased survey frequently recorded — 1461 records compared with 721 effort was unclear, but it predominantly involved 500 m in the previous ten years. The third place ranking of the area and incidental surveys: the increase in 2 ha/20 min Grey Fantail, Rhipidura fuliginosa, 1387 records, might be surveys was more modest (see ratio in table 1). surprising because this species is often claimed to be The statistics in this report were extracted on 5 primarily a summer visitor. However, in case study 2 November 2016 from the General Birdata section of the (page 6) Birdata results will be presented that demon- database portal. strate that Grey Fantails occur regularly in winter. The Surveys were conducted in 182 cells (10′ latitude/ remainder of the ten most recorded species in 2014–15 longitude) during 2014–15, which was approximately were Masked Lapwing, Vanellus miles (1317); then two 50% of the coverage achieved in the previous decade. introduced species, Common Blackbird, Turdus merula Sites surveyed in 2014–15 (figure 1) were well distrib- (1213), and Common Starling, Sturnus vulgaris (1147); uted and included much of the Bass Strait islands. followed by Brown Thornbill, Acanthiza pusilla (1032); Table 1: Comparison of 2014–15 stascs with previous 10 two endemic species, Green Rosella, Platycercus caledonicus years.