Data Zone
Justification of Red List category
This species has a very small breeding population that is declining as a result of fire combined with ongoing hybridisation with Yellow-throated Miners M. flavigula, and is therefore classified as Endangered.
Population justification
Distance analysis estimated 481 (236–983) colonies of Black-eared Miners in Riverland Biosphere Reserve in 2015–2016 (where >95% of the population occurs), with a 61% reduction in the abundance of Black-eared Miners within a 2006 firescar compared to long-unburnt mallee (Boulton 2019). At least 18 colonies were known from Murray-Sunset National Park in 2019 (R. Boulton unpublished data) and two persisted in Annuello Flora and Fauna Reserve in 2014 (Boulton 2014). However, these figures are likely to exaggerate the population size. First, although Black-eared Miners are a communal species, the number of mature adults is only about double the number of colonies because of the skewed adult sex ratio and complex social organisation (Ewen et al. 2001). Second, miners move towards an observer when close by but avoid detection at greater distances, which overestimates abundance. Third, their distribution is clumped even within core habitat; few new colonies were discovered in recent surveys despite extensive off-track areas being walked during the distance transects (Cale 2012, Boulton 2019). These challenges are likely to lead to over-estimation of population size, especially in the Riverland Biosphere Reserve which could be as low as 200 colonies. Population size is also heavily influenced by rainfall, with no breeding in drought and continuous breeding across the year if good conditions persist. Accounting for these uncertainties, the number of mature individuals is set at 400-2,000, with a best estimate of 1,000. More than 95% of these are thought to occur in the Riverland Biosphere Reserve.
Trend justification
Historically, the species declined dramatically owing to clearance and fragmentation of its preferred mallee habitat. As a result, hybridisation with the dominant M. flavigula, which invades remnant habitat patches, is now the greatest threat and continues to drive declines. The Millennium Drought is likely to have affected the population; fires burned all the suitable habitat in the Bronzewing Fauna and Flora Reserve, and fires have reduced the suitable habitat available in the Riverlamd Biosphere Reserve (R. Clarke and R. Boulton in litt. 2016). These threats are therefore thought to be causing ongoing declines and have caused significant declines in the past (Boulton et al. 2021). Earlier population estimates are from 2007, when there were about 200 colonies in Riverland Biosphere Reserve (Clarke et al. 2008), seven in Murray-Sunset National Park and the two in Annuello Flora and Fauna Reserve (Boulton 2014). The Riverland Biosphere Reserve population at that time had declined from an estimated 501 (270–927) colonies following a severe fire in 2006 (Clarke et al. 2005), whilst other populations had declined due to drought and genetic introgression from about 53 colonies (32–85) in Murray-Sunset National Park and 14 in Scotia Sanctuary and Tarawi Nature Reserve in New South Wales, and four in Bronzewing Flora and Fauna Reserve (Baker-Gabb 2007).
Black-eared Miners are endemic to the Murray Mallee region of Victoria, South Australia and New South Wales, Australia. The largest population is in the Riverland Biosphere Reserve, South Australia with much smaller numbers scattered through the Murray-Sunset National Park and in Annuello Flora and Fauna Reserve, Victoria (Boulton 2014, 2019). Of five colonies translocated to Murray-Sunset National Park during 2000–2001, only two colonies were found persisting in close proximity to translocation sites in 2014 (Boulton 2014), despite successful breeding upon release (Clarke et al. 2002, Baker-Gabb 2007); the one colony translocated to Scotia Sanctuary in western New South Wales was overwhelmed by Yellow-throated Miners and hybrids in 2010 (Garnett et al. 2011) and the 45 captive birds released in Bronzewing Flora and Fauna Reserve presumably perished during 2014 when the whole reserve burnt (Boulton 2014).
The species occupies semi-arid mallee habitats, that is, eucalyptus woodland in which individual trees are multi-stemmed from ground level and seldom taller than 10 m (Clarke et al. 2005). Densities are highest in areas containing mallee-Triodia associations, or mallee with an open understorey, situated at least 2 km from clearings that exceed 100 ha (Clarke et al. 2005), that has not been heavily grazed or burnt for 45 years. However, they will forage in much younger mallee if available (Raap et al. 2015) including some 9–10 years post-fire, but at densities 40% lower (Boulton 2019). The required area of intact mallee for a viable population may exceed 13,000 ha (Clarke et al. 2005). The species's distribution in Victoria is positively correlated with stable dunefields with a relatively high loam level, amount of decorticating bark (from which it obtains much of its insect food), tree density, stem density, canopy cover and litter cover. The presence of a mosaic of burn types may have facilitated the genetic isolation of the species from M. flavigula. Populations can breed continuously for over 12 months given favourable conditions such as periods of above average rainfall (Clarke et al. 2005). A study of one colony found that 81.8% of females and only 13.9% of males bred per season (E. Moysey per Clarke et al. 2005). It is a cooperative breeder with up to 13 helpers, mostly males, assisting the nest of a breeding pair (E. Moysey per Clarke et al. 2005). When breeding, adults typically forage short distances from the nest (up to 0.8 km). Colonies may wander over areas of 8-10 km2 in the non-breeding season, although they show high breeding-site fidelity. Their diet consists of invertebrates, lerp and nectar.
The cascade of threats facing the species stems from clearance of the land for agriculture (Fahey 2017), fragmenting intact habitat which has then allowed Yellow-throated Miners M. falvigula to hybridise with the Black-eared Miners (Clarke et al. 2001). Heavy grazing by stock, forming piospheres around water sources, has also favoured Yellow-throated Miners (Harrington 2002; C. Hedger unpublished). A more recent and pervasive threat is extensive and comprehensive fires such as occur in heat waves during drought (Clarke et al. 2016), or a fire regime that precludes the development of old-growth mallee (Connell et al. 2019). The abundance of miners is also strongly influenced by rainfall (Connell et al. 2017). Large-scale fire has been particularly prevalent in the Murray Mallee in the last 20 years (Avitabile et al. 2013), and extreme fire weather (Di Virgilio et al. 2019, Dowdy et al. 2019) driven by longer droughts (Evans et al. 2017) and more frequent heat waves (Herold et al. 2018) is likely to increase in frequency, extent and severity in coming decades. Grazing by goats Capra hircus, rabbits Oryctolagus cuniculus and kangaroos Macropus spp. diminish habitat value by simplifying habitat structure (Harrington 2002, Giljohann et al. 2017).
Conservation Actions Underway
The entire population is within protected areas. It is listed as threatened under appropriate legislation. In reaction to the species's very low numbers in the mid-1990s, a colony of seven males and two females was taken into captivity in order to establish a captive breeding colony. Management actions completed or underway include genetic studies, regular surveys and monitoring, the study of habitat preference in Victoria, the purchase of leases within Riverland Biosphere Reserve, the adoption of a policy of rapid fire suppression within mallee in Victoria and South Australia, research into reproductive biology and ecology, establishment of a captive population, colony translocations, generation of community support and the establishment of a recovery team (Clarke et al. 2002). The threat of M. flavigula is tackled by the closure and revegetation of dams, and strategic removal of colonies. Between 1996 and 2002 intensive field studies located a previously unknown population and a number of isolated colonies throughout the species's historic range (Clarke et al. 2005). These searches identified what is now known to be the largest population of the species, in the Riverland Biosphere Reserve (Clarke et al. 2005). In 2000 and 2001, 60 adult and 30 young birds were successfully translocated from the Riverland Biosphere Reserve to the Murray-Sunset National Park (Clarke et al. 2002). These trial translocations were the first to translocate such a social, cooperative breeding bird, with whole intact colonies containing multiple females that went on to successfully maintain colony cohesiveness and breed after release. A Black-eared Miner Recovery Team has been formed. Advice on threatened mallee birds is being incorporated into fire planning and response. Strategic artificial water closure to reduce grazing pressure.
23-26 cm. Medium-sized, grey honeyeater with black face mask, grey rump and tail concolorous with back. Sexes alike. Mid- to dark grey upperparts. Olive-yellow edged remiges and outer rectrices. Black mask from bill to ear-coverts. Dark grey, sub-moustachial stripe. Grey chin and upper throat, finely mottled on breast. White belly. Yellow bill and skin behind eye. Juvenile more brown. Similar spp. Yellow-throated Miner M. flavigula has white-tipped tail and whitish rump. Hybrid melanotis x flavigula has pale-tipped tail, paler grey on rump and sub-moustachial stripe. Voice Variety of harsh notes, chattering.
Text account compilers
Berryman, A., Vine, J.
Contributors
Allinson, T, Benstead, P., Boulton, R., Clarke, R., Dutson, G., Garnett, S., McClellan, R., Symes, A. & Taylor, J.
Recommended citation
BirdLife International (2024) Species factsheet: Black-eared Miner Manorina melanotis. Downloaded from
https://datazone.birdlife.org/species/factsheet/black-eared-miner-manorina-melanotis on 23/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/11/2024.