FAIRY TERN (STERNULA NEREIS) CONSERVATION IN SOUTH- WESTERN AUSTRALIA A guide prepared by J.N. Dunlop for the Conservation Council of Western Australia. Supported by funding from the Western Australian Government’s State Natural Resource Management Program AckNowleDgemeNts The field research underpinning this guide was supported by the grant of various authorities and in-kind contributions from the Department of Parks & Wildlife (WA) and the Department of Fisheries (WA). The Northern Agricultural Catchment Council (NACC) supported some of the work in the Houtman Abrolhos. Many citizen-scientists have assisted along the way but particular thanks are due to the long-term contribution of Sandy McNeil. Peter Mortimer Unique Earth and Tegan Douglas kindly granted permission for the use of their photographs. The production of the guide to ‘Fairy Tern Conservation in south-western Australia’ was made possible by a grant from WA State NRM Office. This document may be cited as ‘Dunlop, J.N. (2015). Fairy Tern (Sternula nereis) conservation in south-western Australia. Conservation Council (WA), Perth.’ Design & layout: Donna Chapman, Red Cloud Design Published by the Conservation Council of Western Australia Inc. City West Lotteries House, 2 Delhi Street, West Perth, WA 6005 Tel: (08) 9420 7266 Email: [email protected] www.ccwa.org.au © Conservation Council of Western Australia Inc. 2015 Date of publication: September 2015 Tern photos on the cover and the image on this page are by Peter Mortimer Unique Earth. Contents 1. The Problem with Small Terns (Genus: Sternula) 2 2. The Distribution and Conservation Status of Australian Fairy Tern populations 3 3. Threats to the Fairy Tern in Western Australia 6 4. The Biology of Small Terns 8 a. Marine Habitats and Foraging Ecology 8 b. Social Behaviour 8 c. Breeding Biology 9 d. Moulting Patterns in Fairy Terns 10 e. Population Structure and Movements 13 f. Factors Controlling Colony Formation 15 5. Management of Fairy Terns 18 a. Surveillance, Monitoring and Research 18 b. Nesting Habitat Management 21 c. Protecting Colony Areas from Human Encroachment 22 d. Protecting Breeding Colonies from Predators 24 e. Breeding Facilitation Techniques 25 f. Local Fairy Tern Conservation Strategies 26 2015 6. references 28 Figures ralia T us Figure 1. Map showing the distribution of Sternula nereis nereis including the sedentary and a migratory Western Australian sub-populations and the sub-population in south-eastern Australia. 3 ern Figure 2. Map showing the locations mentioned in Western Australia. 4 T Figure 3. The progression of the primary moult in Fairy Terns captured at Penguin Island, h-Wes Shoalwater Bay in September (N=28) and at Rat Island in the Houtman Abrolhos in November (N=11), T December (N=17), January (N=15), February (N=29) and late March /early April (N=42). 13 ou s Figure 4. The age distribution inferred from the plumage, alternate moult and brood patch condition in Fairy Terns captured at Penguin Island, Shoalwater Bay in September (N=28) and at Rat Island in the ion in Houtman Abrolhos in November (N=11), December (N=18), January (N=17), February (N=33) and T late March /early April (N=48). 14 Figure 5. Conceptual Model of the process of colony formation in local breeding populations of the Fairy Tern. 16 Fairy Tern Conserva Fairy 1 the Problem with small All Sternula terns nest in colonies on open shorelines including island and mainland sandy, gravelly or terns (Genus sternula) shelly beaches or banks of coral clinker. Colonies 1 are generally located adjacent to protected marine embayments, sheltered lagoons and estuaries. Where disturbance / predation pressures or habitat loss A group of closely related micro terns are have become unsustainable small terns have adopted currently placed together in the genus Sternula sub-optimal sites (eg. areas vulnerable to flooding) (Bridge et al. 2005). These small tern species or artificial sites such as dredge-spoil banks or dune include the Little Tern S.albifrons of Europe and blow-outs. In extreme cases small terns have even South-east Asia (including northern and eastern taken to nesting on the gravel bed rooves on coastal buildings as has been the case with Japanese Little Australia), Least Tern S. antillarum of North Terns around Tokyo Bay (Go Fujita et al. 2009) and America, Damara Tern of south-west Africa, North American Least Terns in Georgia(Krogh 1999). Peruvian Tern S.lorata of western South America, As the result of the conflict between small tern Yellow-billed Tern S. superciliaris of eastern South breeding behaviour and people, all species of America and the Fairy Tern S. nereis of western Sternula have become conservation dependent in and southern Australia, New Caledonia and New settled areas and are now considered threatened in Zealand. A number of sub-species are sometimes most jurisdictions. In Australia the Little Tern is the recognized, for example the nominate Little Tern subject of a recovery plan in NSW and is considered S.albifrons albifrons in south-eastern Australia and threatened along the south-eastern coast whilst its status in the tropical north remains uncertain. S.albifrons sinensis on the tropical north coast. On the 3rd of March 2011 the Australian Fairy The colonial breeding behaviour of terns has evolved Tern Sternula nereis nereis was listed as threatened to adapt to a variety of factors including the location (vulnerable - Criterion 3) under the Environmental of suitable foraging habitat, the synchronization of Protection & Biodiversity Conservation Act 1999. breeding with prey availability and the avoidance of This species is partially migratory and occurs in at predation. Small terns have behavioural adaptations least five States necessitating the production of a 2015 that reduce the chances of predation, these include national recovery plan (possibly combined with one cryptic eggs and chicks and associated flight and for S.albifrons). ralia attack strategies designed to distract hunters. These T adaptations for nesting on open sandy foreshores were us a no doubt sufficiently effective to maintain populations before European settlement. Today however nesting ern T on shorelines, and especially on beaches, exposes small terns to reduced breeding success and adult survival h-Wes due to their vulnerability to introduced predators, T habitat loss to coastal development and frequent ou s disturbance from human activities. ion in T Fairy Tern Conserva Fairy Photograph courtesy of Peter Mortimer Unique earth 2 the Distribution and An investigation of the genetics of Sterna nereis was conducted across its breeding range to elucidate the Conservation status conservation significance of the small (circa 30-40 2 breeding individuals) and isolated population in of Australian Fairy New Zealand (Baling & Brunton 2005). This study indicated that the New Zealand birds could be tern populations regarded as a separate sub-species S.nereis davisae. Another small population of 200-400 breeding individuals at New Caledonia was also given sub- species status (as S. nereis exsul) based on this genetic Three subspecies of the Fairy Tern Sterna nereis are analysis (Baling & Brunton 2005, Barre et al. 2012). currently recognized. The nominate race S. nereis Genetic differences were also detected between nereis occurs in Western Australia south of Broome, Fairy Terns in Western Australia and south-eastern and in South Australia, New South Wales, Victoria Australia however these were not sufficient to merit and Tasmania. Population estimates in the 2011 treatment as separate sub-species. Perhaps not surprising the highest genetic diversity was found listing advice (Commonwealth of Australia 2011) in the largest population in Western Australia (Baling indicate that there are a few hundred pairs of Fairy & Brunton 2005) suggesting that this region was the Terns breeding in South Australia (in the Gulfs source for the smaller breeding groups founded in region) and Tasmania, 120-150 pairs in Victoria south-eastern Australia. The low genetic diversity with up to 70 individuals in New South Wales. in the satellite populations in New Zealand and The statement cites a population of 1,600 pairs New Caledonia probably reflect the genomes of a small number of founders. for Western Australia although this likely to be a significant under-estimate. All up the population Within Western Australia there appears to be of Australian Fairy Terns is currently considered to two sub-populations. One is sedentary and based along the Pilbara and upper Gascoyne coasts from consist of between 5,000 and 10,000 individuals Exmouth Gulf to the Dampier Archipelago, including across all age classes (Burbidge et al. 1996). Barrow Island and the Monte Bello and Lowendal 2015 ralia T us a ern T Figure 1. Cdgi]Zgc Map showing IZgg^idgn h-Wes the distribution T FjZZchaVcY of Sternula nereis ou nereis including the s sedentary and LZhiZgc6jhigVa^V migratory Western ion in Australian sub- Hdji]6jhigVa^V T populations and the sub-population in south-eastern Australia. CZlHdji]LVaZh K^Xidg^V GZh^YZcihjW"edejaVi^dc B^\gVidgnhjWedejaVi^dc Hdji]"ZVhiZgcedejaVi^dc Tern Conserva Fairy IVhbVc^V 3 Figure 2. Map showing the locations mentioned in Western Australia. Broome 9Vbe^Zg6gX]^eZaV\d BdciZWZaad>haVcYh Port Hedland 7Vggdl>haVcY AdlZcYVa>haVcYh Exmouth :mbdji]<ja[ <VhXdncZ8dVhi L:HI:GC6JHIG6A>6 Carnarvon 2015 H]Vg`7Vn ralia T us a ern Kalbarri GdiicZhi>haVcY T HlVcG^kZg 6Wgda]dh>haVcYh Geraldton h-Wes T <VgYZc>haVcY ou s HV[Zin7Vn ion in T EZZa:hijVgn PERTH Mandurah AZhX]ZcVjai>caZi Bunbury Esperance GZX]ZgX]Z6gX]^eZaV\d Fairy Tern Conserva Fairy Denmark Albany CdgcVaje>caZi 4 L^ahdc>caZi Archipelagos. These Fairy Terns nest from late July to what scale local breeding groups (which probably late September (Johnstone & Storr 1998, J.N. Dunlop establish colonies at a number of sites) represent pers.obs.). This area also appears to be a wintering area conservation management units within the migratory (June-August) for a second, migratory sub-population sub-population.