| Criterion (a). Whether the habitat is used during periods of stress. Examples of period of stress: Flood, drought or fire. N/A Criterion (b). Whether the habitat is used to meet essential life cycle requirements. Examples: Foraging, breeding, nesting, roosting, social behaviour patterns or seed dispersal processes. Historically, the distribution of the Black-eared Miner was widespread and included in the Murrey Mallee of Victoria, South Australia and New South Wales. The Black-eared Miner’s current distribution is much reduced, with over 95% of known colonies occurring in the Gluepot, Calperum and Taylorville sites. The species has retracted to this area primarily because of habitat loss and altered fire regimes across its former range. The listed habitat is used for foraging, breeding, nesting and roosting (all essential life cycle requirements). Black-eared Miners occur predominately in mature mallee eucalypt woodland, in areas that have not been burnt for at least 40 years and have not been cleared, although post-fire regenerating mallee of 5-10 years or older may provide occasional foraging habitat (Starkes 1987; McLaughlin 1990; Muir et al. 1999). Sites with the most genetically true colonies are more than 5 km from dams and man-made clearings (Clarke & Clarke 1999b, Muir et al. 1999). Black-eared Miners inhabit shallow sand mallee and chenopod mallee. The vegetation is dominated by multi-stemmed mallee eucalypts, including Eucalyptus Dumosa, E. gracilis, E. oleosa and E. socalis, usually in association with a ground layer dominated by either Spinifex Triodia scariosa, or shrubs of the families Chenopodiaceae and Zygophyllaceae (Starks 1987; McLaughlin 1992; Muir et al. 1999). The Black-eared Miner eats mainly invertebrates and lerp (the sugary exudate produced by psyllids). Prey is obtained mainly from gleaning and probing decorticating bark, limbs and twigs of eucalypts and gleaning from foliage, although birds will also forage on the ground and hawk for flying insects (McLaughlin 1990). Nectar from Eucalyptuss spp., Eremophila spp. And Grevillea huegelii is also taken. All of these plant species are found in the listed area. Criterion (c). The extent to which the habitat is used by important populations. NB: An important population is one that is necessary for a species’ long-term survival and recovery. This may include populations that are: key source populations either for breeding or dispersal, populations that are necessary for maintaining genetic diversity, and/or populations that are near the limit of the species range. Over 95% of the known colonies of the Black-eared Miner occur in the Gluepot, Calperum and Taylorville sites. This area is therefore the most important source population for breeding and dispersal as well as being a source of individuals for recovery actions such as translocation. The area supports the most genetically true populations and is therefore essential for maintaining the genetic integrity of the species. Criterion (d). Whether the habitat is necessary to maintain genetic diversity and long-term evolutionary development. This habitat is necessary to maintain genetic diversity and long-term evolutionary development. A major cause of decline is introgressive hybridisation by the conspecific Yellow-throated Miner (Schodde 1981; Starks 1987; McLaughlin 1990). Black-eared and Yellow-throated Miners were clearly separable by phenotypic characters before extensive clearing occurred after 1950 (Clarke et al. in press). McLaughlin (1992) demonstrated that habitat occupied by breeding Black-eared Miners is significantly structurally dissimilar from Yellow-throated Miner habitat, and that the two species are predominately allopatric (ie. They occupy different habitats). Clearance and modification of vegetation in areas of the species former range has resulted in creation of habitat intermediate in structure between that favoured by the Yellow-throated Miner and habitat favoured by the Black-eared Miner. This has led to the rise of colonies of hybrid miners. The flow of genetic material between the two species is maintained by the presence of hybrid miner colonies (these colonies would not have been present prior to extensive land clearing). Uncontrolled genetic introgression will eventually result in the loss of the biological and genetic diversity contributed by the Black-eared Miner (Cade 1983). Clearing or fragmentation of habitat is highly undesirable and may result in genetic swamping by Yellow-throated Miners. Intact mallee inhibits this genetic introgression, and is therefore necessary to maintain the genetic integrity and diversity of the Black-eared Miner. Criterion (e). Whether the habitat is necessary for use as corridors to allow the species to move freely between sites used to meet essential life cycle requirements. N/A Criterion (f). Whether the habitat is necessary to ensure the long-term future of the species or ecological community through reintroduction or re-colonisation. Over 95% of known colonies occur within the Gluepot, Calperum and Taylorville sites. Successful translocation of the species to areas of suitable habitat in New South Wales and Victoria has occurred with bird sourced from the Calperum and Gluepot sites. Criterion (g). Any other way in which habitat may be critical to the survival of a listed threatened species or a listed threatened ecological community. N/A |