Movements of a nomadic waterfowl, Grey Teal Anas gracilis, across inland Australia – results from satellite telemetry spanning fifteen months D.A. Roshier1,*, N.I. Klomp1 & M. Asmus1 Roshier D.A., Klomp N.I. & Asmus M. 2006. Movements of a nomadic waterfowl, Grey Teal Anas gracilis, across inland Australia – results from satellite telemetry spanning fifteen months. Ardea 94(3): 461–475. We used lightweight satellite transmitters to follow the movements of 17 Grey Teal Anas gracilis between September 2003 and November 2004 in two contrasting landscapes, the agricultural districts of southern Australia and the desert landscapes of the interior. Tagged birds moved large dis- tances (up to 343 km) between occupied sites in a short period (hours), remained in the vicinity of those sites for extended periods (months), ven- tured up to 453 km from their point of release and travelled more than 2000 km in one year. We describe patterns of movement in a nomadic waterfowl for 15 months from September 2003, a period of severe drought. Based on the current analysis there appears to be no remarkable difference in the observed patterns of movement of those released in the agricultural landscapes and those released in the desert. As in waterfowl elsewhere, movements appear to occur in response to changes in local food abundance that threaten survival or the imperative to move in order to breed successfully. In Grey Teal, the proximate cues for movement transcend the local landscape and some birds are responding to temporary cues hundreds of kilometres distant. This is in contrast to the universal seasonal cues associated with migration systems else- where. Key words: arid environments, capital breeding, migration and moon phase 1Institute of Land, Water & Society, Charles Sturt University, P.O. Box 789, Albury 2640 Australia; *corresponding author ([email protected]) INTRODUCTION on long-distance seasonal migrants or seabirds that range over vast tracts of ocean but are The nature and extent of movements of nomadic philopatric to breeding location (e.g. Berthold et species remain enigmatic due to our inability to al. 1992, 1995, Meyburg & Lobkov 1994, Nicholls observe individual birds repeatedly or follow their et al. 1995, Walker et al. 1995, Davis et al. 1996, movements in real-time. Satellite telemetry is now Hake et al. 2001, 2003, Beekman et al. 2002, commonly used to track the movements of birds – Clausen et al. 2003, Fox et al. 2003; but see Petrie providing new insights into their movement pat- & Rogers 1997). Nomadic species respond to terns, migration routes, wintering sites and forag- changes in resource distribution that vary on other ing strategies. Most telemetry studies have been than annual cycles and patterns of movement are 462 ARDEA 94(3), 2006 considerably more variable than the north-south Lack of understanding of movements also lim- movements observed in many northern temperate its our understanding of the dynamics of Austra- long-distance migrants. lian waterfowl populations in time and space. The In Australia, evidence suggests that most scattered distribution of water across an otherwise waterbirds interact with available habitat at broad hostile landscape imposes a spatial structure on scales (Kingsford & Norman 2002; see Marchant & waterbird populations that may limit the move- Higgins 1990) and many respond quickly to ment of individuals within or between sub-popula- changes in wetland distribution due to flooding tions for extended periods (years). However, it is and inundation of temporary lakes (Minton et al. likely that most constraints imposed by the spatial 1995, Kingsford et al. 1999, Alcorn & Alcorn 2000, distribution of wetlands are temporary and the iso- Roshier et al. 2002). The distribution and extent of lation of individuals and sub-populations is allevi- wetlands across inland Australia is at times vast ated by the mobility and dispersal capabilities of but virtually all are temporary (Roshier et al. many species (see Frith, 1957, 1959, 1962, 1963, 2001), necessitating the need for the birds that use Lawler et al. 1993, Minton et al. 1995, Kingsford them to move to survive and reproduce. Depend- 1996). What is unclear is the nature and extent of ing on the taxonomy of movement used, these those movements and the physiological factors movements could be described as nomadic (Nix constraining them. 1976, Ford 1989, Griffioen & Clarke 2002), rang- In this paper we use satellite telemetry to ing (Dingle 1996), migration, or more simply non- examine the movements of Grey Teal across the sedentariness (Roshier & Reid 2003). desert landscapes of the Lake Eyre Basin and the The broad-scale movement patterns of many agricultural landscapes of the Riverina in southern Australian birds are poorly understood, particu- NSW. Dingle (1996) used the Grey Teal as an larly the movements of birds into, within and exemplar of what he described as ‘ranging’ behav- across the arid inland of the continent (Griffioen & iour, where an individual exploring an area seek- Clarke 2002). The movement of waterfowl into ing feeding and/or breeding habitat would cease and out of the arid interior of the continent and movement once suitable habitat was encountered. the significance of wetlands there to the mainte- This is in contrast to ‘migration’ during which nance of the broader waterfowl population has movement between breeding and non-breeding received increasing interest in the last decade or so ranges is undistracted and responses to resources (Lawler & Briggs 1991, Maher & Braithwaite are temporally suspended or suppressed (Dingle 1992, Lawler et al. 1993, Kingsford & Porter 1993, 1996). In this first contribution from an ongoing 1994, 1999, Halse et al. 1998, Kingsford 1996, study, we describe patterns of movement in a Kingsford et al. 1999, Roshier et al. 2001, 2002). nomadic waterfowl species, the Grey Teal, and To date, the only direct evidence of movement of interpret those movements in relation to existing waterfowl between the arid inland and more mesic models of bird movement and migration. areas comes from banding studies, although the data are few. Of the thousands of birds ringed by Frith (1957, 1959, 1962, 1963) at Griffith in METHODS southern NSW and elsewhere, a few bands were recovered in the arid zone, indicating movement We used lightweight (<20 g) satellite transmitters into that region. Lawler et al. (1993) ringed 746 to follow the movements of 17 Grey Teal in two Grey Teal Anas gracilis at Lake Altiboulka in the contrasting landscapes, the agricultural landscapes arid northwestern corner of NSW. All 19 recovered of the Riverina region of southern New South rings were from birds shot in southern NSW and Wales (n = 9) and the arid landscapes of the Lake South Australia demonstrating movement the Eyre Basin (n = 8), in the period between Septem- other way. ber 2003 and November 2004. Roshier et al.: MOVEMENTS OF NOMADIC GREY TEAL 463 Study areas produce a diverse range of highly productive but The Riverina is a broad flat region in the southern mostly ephemeral wetland habitats for waterbirds part of the Murray-Darling Basin bisected by the and other biota (Puckridge 1998, Sheldon et al. Murrumbidgee River and bounded by the Murray 2002, Bunn et al. 2003). River to the south. Both river valleys have a long history of irrigation development and are the most Tracking of Grey Teal developed rivers in Australia (Kingsford 2000), Grey Teal are wide ranging and dispersive over with water diverted for the production of rice, most of the Australian continent and are only grains, vegetables, citrus, grapes and pasture. The absent from the driest regions of the great deserts region has hot, dry summers and cool, damp win- of the western half of the continent (Fig. 1). Grey ters. Mean annual rainfall declines westward Teal use a wide range of aquatic habitats but most across the region from c. 400 mm in the east to c. favour large, often temporary, shallow inland wet- 300 mm in the west. The most significant wet- lands that provide an abundance of aquatic vege- lands in the region are the Lowbidgee wetlands at tation and invertebrates for a limited period the confluence of the Lachlan and Murrumbidgee (Marchant & Higgins 1990 and references Rivers, Fivebough Swamp and the Barmah Forest therein). Birds were caught using funnel traps on the Murray River. The Lowbidgee wetlands baited with grain (McNally & Falconer 1953) at include an area of 15 000 ha of Common Reed two locations in southern NSW, Fivebough Swamp Phragmites australis, Cumbungi Typha spp., River (34.53°S, 146.44°E) near Leeton and Barrenbox Red Gum Eucalyptus camaldulensis and rush Swamp (34.13°S, 145.86°E) near Griffith, and at Eleocharis spp. and Juncus spp. (Macgrath 1992). Lake Hope (28.38°S, 139.25°E) c. 1000 km to the Fivebough Swamp is a large (400 ha) natural northwest in northern South Australia (Fig. 1). depression with managed water levels in the midst Only adult birds weighing c. 500 g or more were of agricultural enterprises that is listed as a fitted with a transmitter and harness. All birds Ramsar site and ‘Wetland of national importance’ were released at their point of capture. (Environment Australia 2001). The Barmah- Two types of satellite transmitters were Millewa Forest is 65 000 ha in area and is the deployed: four transmitters had batteries that were largest river Red Gum forest in Australia (Kings- solar-enhanced (Microwave Pico PTT) and 13 did ford 2000). not (Northstar Solar PTT). Transmitters were The Lake Eyre Basin is a vast (1 140 000 km2) attached to the back of each bird by a harness internally draining basin of varied landscapes of comprising a neck loop and a body loop of 6 mm longitudinal sand dunes, hard gibber (stony) Teflon ribbon (Bally Ribbon Company, P/L).