Carnaby’s Cockatoo (Calyptorhynchus latirostris) identification of nocturnal roost sites and the 2010 Great Cocky Count. Report prepared for the WA Department of Environment and Conservation Quinton Burnham1, Geoff Barrett2, Mark Blythman2 and Raana Scott1 1Birds Australia, Western Australia 2DEC, Western Australia August 2010 Carnaby’s Cockatoo roost survey contact: Government of Western Australia Dr Geoff Barrett Department of Environment and Conservation Regional Ecologist Swan Region Department of Environment and Conservation 7 Turner Avenue Technology Park Bentley WA 6102 Email: [email protected] © Government of Western Australia 2010 July 2010 This work is copyright. You may download, display, print and reproduce this material in unaltered form only (retaining this notice) for your personal, non-commercial use or use within your organisation. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to the Department of Conservation and Environment. This document has been produced as part of the Carnaby’s Cockatoo recovery program, under the “High Priority recovery action for matters of national environmental significance in Western Australia” project funded through the WA Natural Resource Management (NRM) Program. Acknowledgements The Department of Environment and Conservation would like to thank those who provided location data for existing roost sites, in particular, Tony Kirkby and Ron Johnstone from the WA Museum, Dr Hugh Finn from Murdoch University and Professor Will Stock (Edith Cowan University). We thank the Birds Australia (WA) Carnaby’s Cockatoo Project Advisory Group for providing advice and guidance during the project. Without the 350 volunteers who enthusiastically and willingly gave up their time to count cockatoos, this project would not have been possible, a special thanks to them all. Judith O’Keeffe, John Hudson and Warwick Boardman helped with input of computer data. All photographs in this report are the property of Margaret Owen, who graciously allowed them to be used. 1 Summary • This report presents the findings of the 2010 Carnaby’s Cockatoo night roost survey, culminating in the Great Cocky Count (GCC) undertaken on 7 April 2010, which aimed to identify Carnaby’s Cockatoo nocturnal roost sites in the DEC Swan Region. • The survey investigated some 222 sites and following database searches, field visits and the 2010 GCC, the number of known Carnaby’s Cockatoo roosts was increased from 70 to 129. • The extensive search effort by DEC during this survey and prior to the GCC, gives us confidence that few large metropolitan roosts would have been overlooked. • On the night of the GCC, approximately half of the roosts were unoccupied, supporting the view that many roost locations are only used at certain times. • The number of birds per site and total number of birds counted were greater in the Gnangara area compared with the adjacent, extensively cleared and urbanized areas north of the Swan River. • There was no statistically significant difference in the number Carnaby’s Cockatoo at each roost location in 2006 compared with the 2010 GCC. However, the trend was towards there being fewer birds per roost in 2010. This was consistent with a decline in the total number of birds counted at these same locations. • Decline in the number of birds at two roost locations since 2006 (R2 and DEC14) appears to be a direct result of pine removal. • The GCC 2010 total count of 6,672 Carnaby’s Cockatoos supports an estimated population of 8,000 to 10,000 birds for the Swan Coastal Plain and adjacent escarpment. • A further three follow up Cocky Counts have been held, once a month, since the April 2010 GCC. The level of community support and the results to date, highlight the value of well structured community-based roost surveys for monitoring populations of Carnaby’s Cockatoos. 2 Contents Summary..................................................................................... 2 Contents ..................................................................................... 3 Background.................................................................................. 4 Aims .......................................................................................... 6 Methods...................................................................................... 7 Locating roost sites ..................................................................... 7 The roost count method................................................................ 8 Count instructions: ...................................................................... 9 Volunteer recruitment.................................................................10 Results ......................................................................................11 Location of roost sites .................................................................11 Carnaby’s Cockatoo Roost surveys...................................................15 Roost tree species......................................................................16 Estimated number of birds in northern Swan Coastal Plain and adjacent escarpment (within DEC Swan Region)..............................................16 Distribution of birds across DEC Swan Region......................................17 Comparison with GCC 2006 ...........................................................20 Discussion...................................................................................22 The Great Cocky Count................................................................22 Regional and temporal variation.....................................................22 Comparison with the 2006 GCC ......................................................23 So how many Carnaby’s Cockatoos visit the Swan Coastal Plain in DEC Swan Region? ...................................................................................24 Where to from here? ...................................................................25 References .................................................................................26 Table 1: Source of roost location data....................................................................... 13 Table 2: Search effort to locate new roost sites ..................................................... 13 Table 3: Carnaby’s Cockatoo roost count summary ................................................ 14 Table 4: Number of Carnaby’s Cockatoos in different areas................................. 19 Figure 1: Location of 222 potential and known roost sites in the DEC Swan Region............................................................................................................................... 12 Figure 2: Five areas within the DEC Swan region..................................................... 18 Figure 3: Comparison with the 16 roosts surveyed in 2006.................................... 21 Appendix 1: Great Cocky Count 2010 data sheet..................................................... 28 Appendix 2: Media information ................................................................................... 34 Appendix 3: Location details and counts................................................................... 42 Appendix 4: Counts of Carnaby’s Cockatoo at 10 roost locations......................... 58 3 Background The Carnaby’s Cockatoo (Calyptorhynchus latirostris) is one of two species of white-tailed black cockatoo endemic to the south-west of Western Australia. Carnaby’s Cockatoos were once numerous in Western Australia, however, since the late 1940s the species has suffered a predicted 30% contraction in range, a 50% decline in population and between 1968 and 1990 has disappeared from more than a third of its breeding range (Saunders 1990; Saunders and Ingram 1998). These declines have resulted in the Carnaby’s Cockatoo being listed as 'rare or likely to become extinct' under the Western Australian Wildlife Conservation Act 1950 and it has been ranked as Endangered by the Western Australian Threatened Species Scientific Committee using IUCN (1994) Red List Categories and Criteria. The Carnaby’s Cockatoo is also listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. In 2002 a recovery plan for the species was put in place by the Department of Conservation and Land Management (subsequently the Department of Environment and Conservation, DEC) (Cale 2003). Carnaby’s Cockatoos generally display a seasonal migratory pattern, whereby they are predominantly dispersed throughout the Avon Wheatbelt Bioregion during the breeding season (July to December, Saunders 1990) then shift to higher rainfall coastal areas where they form large flocks during the non- breeding season (December-July) (Saunders 1974, 1980, 1990; Berry 2008). More recently, breeding sites have been confirmed in coastal and near- coastal areas (DEC unpublished data) but it is unclear whether breeding on the coastal plain occurred historically or represents a shift in response to diminished habitat availability (as has been suggested by Shah, 2006). 4 The declining number of Carnaby’s Cockatoos has been attributed primarily to the loss of habitat in the wheatbelt (Saunders 1980, 1990; Saunders and Ingram 1998). However, more recently the impact of increased clearing of the feeding areas on the Swan Coastal Plain has been recognized as being a significant factor (Finn