Conservation of old-growth dependent mallee fauna
Prepared by David Baker-Gabb for the Black-eared Miner Recovery Team, February 2001
(Revised February 2003)
8. Guide To Decision Makers
- Clearing and fragmentation
- Habitat degradation
- Genetic introgression
- Large fires
- Definition of 'old growth' mallee
There are four major causes of decline of the Black-eared Miner that land managers and other decision makers need to be aware of: (i) clearing and habitat fragmentation, (ii) habitat degradation, (iii) genetic introgression and (iv) large fires (see also section 4 "Decline and Threats"). The following actions may therefore hamper the Black-eared Miner's viability and recovery:
Clearing or fragmentation of blocks of intact mallee has caused regional extinctions of Black-eared Miners and is therefore highly undesirable. Clearing and fragmentation may result in the death of birds or their subsequent genetic swamping by Yellow-throated Miners. Fragmentation may result from clearing several small areas within or around an intact block, or by clearing wide easements through it. Fire access tracks about 5m wide do not constitute a wide easement or a threat.
Dams with their associated clearings and degradation by herbivores attract Yellow-throated Miners, thereby increasing the likelihood of genetic introgression. Putting new dams in blocks of intact mallee is highly undesirable and allowing current dams to persist and provide water for herbivores in conservation reserves is not recommended. Above-ground tanks are recommended for fire fighting purposes.
Yellow-throated Miners have genetically swamped Black-eared Miners in the past and continue to do so in some fragmented areas. Allowing individual Yellow-throated Miners or their colonies to remain in close proximity to Black-eared Miners is therefore undesirable because of the hybridisation that is likely to take place.
Because Black-eared Miners require mallee that has not been burnt for 40 or more years, large wildfires constitute a threat of only slightly lesser magnitude than clearing. Fires may also lead to habitat fragmentation and regional extinctions. Strip burns c100m wide with lengths of 1-5 km burnt in a year (eg Willson 1999) to provide strategic fire breaks and protect large blocks of intact mallee should not pose a threat. Every effort should be made to contain the spread of wildfires in Black-eared Miner habitat.
In mallee where Black-eared Miners occur, even large fires generally leave substantial pockets of unburnt mallee where the birds can breed and still forage in the surrounding regenerating areas.
For the purposes of this Recovery Plan 'old growth' mallee is defined as 'mallee that has remained unburnt for 40 years or more'.