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Subspecies Conservation Summary Yellow Chat (Alligator Rivers) Epthianura crocea tunneyi Mathews, 1912 Meliphagidae Conservation status Endangered B2ab(ii,iii,iv,v), C2a(ii) Reasons for listing Population of 250–2500 mature individuals occupying an area <500 km2 in a single subpopulation at <5 locations with a continuing decline in area occupied, habitat quality, no. locations and no. mature individuals, probably from a combination of introduced weeds, feral animals and saline intrusion Status 2000 Endangered B2ab(ii,iii,iv,v), C2a(ii) Status 1990 Endangered B2ab(ii,iii,iv,v), C2a(ii) Taxonomy E. c. macgregori (Capricorn) is Endangered, E. c. crocea (inland northern Australia) is Least Concern, as is the species Taxonomic uniqueness: medium (43 genera/family, 4 species/genus, 3 subspecies/species) Range Recorded from a small number of sites in Adelaide R., Mary R., Wildman R., South Alligator R. and East Alligator R. floodplains in the Northern Territory (Keast 1958; Armstrong 2004). Most records are from within Kakadu National Park but the relative importance of the different floodplains is unknown. Occasional records elsewhere, mostly from Darwin to Oenpelli, are probably of dispersive individuals which make up what is presumed to be a single subpopulation. Abundance Based on recording 96 individuals in 32 observations over 2 weeks, Armstrong (2004) estimated a population of <300 in Kakadu National Park. Anecdotally the subspecies was more widespread in the past and a continuing decline is inferred from the nature of the threats and their expanding influence on chat habitat. Ecology Inhabits alluvial coastal and subcoastal grassy floodplains, primarily near floodplain depressions and channels, typically sparsely vegetated with a small number of grasses, sedges and forbs, and aggregates around refugial waterholes in the late dry season (Armstrong 2004). Also recorded from tall grasslands and samphire shrublands (Woinarski et al. 2007). The habitat is frequently burnt and is flooded every wet season. It feeds in small groups on insects, mainly on the ground, in grassy or open areas including the muddy edges of wetlands, and amongst low vegetation (Higgins et al. 2001; Armstrong 2004). A generation time of 5.8 years (BirdLife International 2011) is derived from an age at first breeding of 1.5 years (extrapolated from Manorina and Phylidonyris) and a maximum longevity in the wild of 10.1 years (extrapolated from other Meliphagidae). Threats Threatened by habitat degradation caused by exotic plant species, grazing, feral pigs Sus scrofa, altered fire regimes and saltwater intrusion. Invasion by the weeds Mimosa pigra, Para Grass Urochloa mutica, Gamba Grass Andropogon gayanus and perhaps Aleman Grass Echinochloa polystachya and Olive Hymenachne Hymenachne amplexicaulis, which are established across much of the chat’s range may render the habitat unsuitable, although the relationship between these weeds and chat abundance has not been established and the largest population of E. c. macgregori occurs on grazed land dominated by H. amplexicaulis (Houston and Melzer 2008). However, while grazing by cattle does not seem to affect E. c. macgregori, wallowing by feral Water Buffalo Bubalus bubalis will degrade habitat of E. c. tunneyi if buffalo numbers are allowed to return to high densities. Armstrong (2004) did not record the species in otherwise suitable habitats where mud-banks had been significantly disturbed by pig-rooting. At the end of the dry season, both feral pigs and chats concentrate in relatively small areas of suitable habitat. Regular patch burning of parts of the floodplain may be necessary to maintain habitat diversity (Lucas et al. 1997). The plains are also at risk from saltwater incursion as a result of sea level rise, though this is not straightforward as mobilisation of sediments by rising sea levels can lead to reemergence of freshwater wetlands at a higher level (Winn et al. 2006). Predation by feral cats Felis catus has been suggested as a threat (Woinarski et al. 2007). Given the threats of weeds and saltwater intrusion, the subspecies is assessed as having 5 locations: the floodplains of © Birds Australia 2011 Published by CSIRO Publishing, http://www.publish.csiro.au/ Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne. Current eligibility against IUCN Red List Criteria IUCN category A Criteria eligibility Not applicable: past, current or future population declines are thought unlikely to exceed 20% in any 3-generation period B Endangered: AOO <500 km2, at ≤5 locations with plausible future threat, inferred continuing decline in AOO, habitat quality, no. individuals C Endangered: population 250–2500 mature individuals, suspected continuing decline, >95% mature individuals in 1 subpopulation D Vulnerable: population <1000 mature individuals E Not applicable: no population viability analysis undertaken the Adelaide R., Mary R., Wildman R., South Alligator and East Alligator Rivers. Conservation objectives 1. A viable population 2. Evidence-based management of chat habitat Information required 1. Population trends 2. Movements, habitat and threats 3. Effect of management actions Management actions required 1. Survey population and establish a monitoring protocol 2. On pastoral properties maintain grazing at levels that do not cause habitat deterioration 3. Manage pests, particularly feral pigs 4. Control or eradicate invasive weeds that are affecting taxon Bibliography IUCN Red List assessment data Estimate Reliability Extent of occurrence trend 1700 km2 stable medium low Area of occupancy trend 170 km2 decreasing low low No. of mature individuals trend 500 decreasing medium medium No. subpopulations 1 high No. locations 5 medium Generation time Global population share 5.8 years low 100% high Houston W and Melzer A (2008) ‘Yellow chat (Capricorn subspecies) Epthianura crocea macgregori recovery plan’. Report to Department of the Environment, Water, Heritage and the Arts, Canberra. Queensland Environmental Protection Agency, Brisbane. Keast A (1958) The relationship between seasonal movements and the development of geographic variation in the Australian chats Epthianura Gould and Ashbyia North (Passeres: Muscicapidae, Malurinae). Australian Journal of Zoology 6, 53–68. Lucas D, Gapindi M, Russell-Smith J (1997) Cultural perspectives of the South Alligator River floodplain: continuity and change. In Tracking Knowledge in North Australian Landscapes: Studies in Indigenous and Settler Ecological Knowledge Systems. (Eds DB Rose and A Clarke) pp. 120–140. North Australia Research Unit, Darwin. Winn KO, Saynor MJ, Eliot MJ, Eliot (2006) Saltwater intrusion and morphological change at the mouth of the East Alligator River, Northern Territory. Journal of Coastal Research 22, 137–150. Armstrong M (2004) ‘The Yellow Chat Epthianura crocea tunneyi in Kakadu National Park’. Unpublished report. Parks Australia (North). Woinarski J, Pavey C, Kerrigan R, Cowie I, Ward S (Eds) (2007) Lost from Our Landscape: Threatened Species of the Northern Territory. Northern Territory Government, Darwin. BirdLife International (2011) ‘Species factsheet: Epthianura crocea’. Retrieved 17 January, 2011 from <http://www.birdlife.org/>. Comments received from Martin Armstrong, Peter Kyne, Simon Ward, John Woinarski Higgins PJ, Peter JM, Steele WK (Eds) (2001) Handbook of Australian, New Zealand and Antarctic Birds. Volume 5: TyrantFlycatchers to Chats. Oxford University Press, Melbourne. © Birds Australia 2011 Published by CSIRO Publishing, http://www.publish.csiro.au/ Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne.