Threatened Species Scientific Committee 4 THREATS The Mallee Bird Community is impacted by several threats; primarily clearing of mallee habitats and their fragmentation into smaller; degraded remnants that are more susceptible to invasive species; fire impacts and climate change and hence less suitable to sustain a diverse assemblage of birds and the other flora and fauna on which they depend (Arthur Rylah Institute 2003 Mallee CMA 2012 Boulton and Lau 2015).

These include a greater risk of weed and feral animal invasion; alteration of local climate and increased susceptibility during droughts; heatwaves; dust storms and other weather extremes; and encroachment of adjoining land use impacts such as chemical spray drift and livestock grazing.

Threatened Species Scientific Committee Threat factor Threat Status Impacts and evidence base Climate change Timing Ongoing Climate change projections are available for the MDD region (CSIRO and and severe Future BOM; 2015).

Projected climatic change is likely to compound the existing impacts from habitat loss; fragmentation; edge effects; invasive species and broad scale bushfires.

Lowland mallee species appear to be very sensitive to climate change; with the predicted disappearance of Mallee Western Whipbird and Mallee Emu wren bioclimates from Victoria and a 90 decline in bioclimatic range for Malleefowl and Red lored Whistler (Bennett et al. 1991 Brereton et al. 1995).

Extent and decline of mallee woodlands and shrublands in the MDD grouped by subregions based on location; climate and land use impacts.

Extinction of the mallee bird community is mostly likely if the extensive mallee reserves are impacted through one; or a succession of; catastrophic fire seasons; possibly mediated through climate change and occurring in combination with other serious ongoing threats; such as invasive species; that collectively have already caused significant degradation.

Fires; in themselves; are a natural feature of mallee systems but threats to integrity arise when the risk of fire and the consequences of its impacts are altered by human activities and; potentially; climate change.

Climate change models project; with high confidence; harsher fire weather for at least the Murray Basin in the future (CSIRO and BOM 2015).

Threatened Species Scientific Committee A further factor to consider is the effect of projected climate change on; not only future fire weather; but potential bird responses to fire and climate change.

The capability of Mallee Birds to respond to climate change through dispersal southward is severely constrained.

Connell et al. (2021) examined the impact of climate extremes on bird abundances and their response to time since fire in the Murray Mallee during 2006 15.

Climatic extremes may influence what resources are available for mallee birds at sites of different fire age; hence their variable responses to time since fire.

Enhanced greenhouse climate change and its potential effect on selected fauna of south eastern Australia a trend analysis.

Fire is a key element in the landscape scale habitat requirements and global population status of a threatened bird The Mallee Emu wren (Stipiturus mallee).

There is also the influence of disturbances; notably fire regimes; that can temporarily remove the tree canopy or stimulate regeneration with impacts on some of the component bird species.

Summary of threats facing the ecological community Threat factor Threat Status Impacts and evidence base Altered fire Timing Ongoing Mallee vegetation are fire prone systems where much of the vegetation is regimes adapted to particular fire regimes.

Many plant species show adaptations Severity Most for recovery after fire through resprouting from regenerative organs or seasons minor; germination from a seed bank. as only some Many birds have no special adaptations to fire other than to temporarily areas impacted. flee to unburnt areas (Boulton and Lau 2015).

Fires in the MDD bioregion Major during often burn extensive areas of vegetation remnants a sequence of such extreme fire fires collectively accounted for 89 of the Murray Mallee subregion burnt seasons. between 1972 and 2007.

Most and specific fires initiate declines in bird populations due to exposure to heat or smoke areas; especially during the event; or reduced availability of food and shelter in the early old growth post fire years.

Different species respond differently to post fire changes in vegetation composition and structure.

The already fragmented landscape means that fire poses a serious threat to smaller remnants that may be suitable for the bird community (Sluiter et Threatened Species Scientific Committee Threat factor Threat Status Impacts and evidence base al. 1997).

Fire impacts to smaller remnants could result in temporary loss of all suitable habitat locally; as happened at Bronzewing Flora and Fauna Reserve in 2014; or reduce value as refuges for mallee bird species.

However; this can also have the impact of insufficient fire leading to senescence of native vegetation and hence loss of suitable habitat and resources; which in turn leads to the local loss of the Mallee Bird Community in long unburnt areas.

For example; where birds are not killed outright by catastrophic bushfires; their responses to fire correspond with postfire changes in the vegetation and associated other fauna on which different members of the bird assemblage may rely (Woinarski 1999 Watson et al. 2012 Howling et al. 2019).

Smaller scale clearing and tidying of bushland along roadsides and around houses; buildings and other infrastructure; including for fuel reduction purposes; adds to this threat.

The forecast over the next century is for higher weather temperatures; declining rainfall; especially in the cooler seasons; and Severity Minor to harsher drought and fire weather. date likely Major impacts in future.

Post fire recovery of mallee heathlands can be hampered by drought conditions.

The highest levels of protection from clearing; inappropriate burning or other detrimental habitat impacts should be given to o Remnants that provide features such as hollows; fissures and bark ribbons that provide important resources for many mallee bird species (Gibbons Lindenmayer 2002 Haslem et al. 2012) and o Mallee habitats that support at least three of the characteristic bird species (Table 2.1); irrespective of the current growth stage of the trees.

Threatened Species Scientific Committee o Use available ecological information to avoid detrimental fire impacts on key and susceptible species in the ecological community for instance; do not burn in a way that is detrimental to long term habitat features such as mature trees. o Consider weather conditions and do not burn in or adjacent to the ecological community when soil moisture is low; or dry conditions are predicted for the coming season as flora and fauna are already stressed; recovery will be too slow and erosion may occur or weeds and pest animals become established while the vegetation cover is reduced.

Monitor the impacts of fires; especially in severe fire seasons; at sites recovering from fire.

These threats do not operate independently but may interact in complex ways; for instance the interactions between fragmentation and fire reviewed by Driscoll et al. (2021) and discussed further below.

Threatened Species Scientific Committee Loss of integrity due to fire regimes Fire is a key driver of mallee systems across Australia (Bradstock and Cohn; 2002 Yates et al. 2017 Keith et al. 2020).

Reserve scale fires that impact entire mallee remnants are a key threat to mallee birds; especially if the reserves are smaller in size and or contain threatened bird species; Other large fire events may not affect entire remnants but can homogenise the fire age class and vegetation structure across a wide area (Brown et al. 2009); sometimes in ways that render habitats unsuitable for certain mallee bird species.

The Mallee Fire and Biodiversity project has identified a chronosequence of how various habitat attributes change over post fire intervals up to 110 years in the Murray Mallee; with many attributes showing non linear responses (Clarke et al. 2010 Haslem et al. 2011 Watson et al. 2012).

For instance; Triodia cover; an important resource for mallee bird species such as wrens; increases over the first 30 years after fire then declines gradually.

In Triodia Mallee; litter and ground fuel cover increase for the first 20 or so years after fire; then plateau before a late decline after 80 years; as does the cover of the ground and mid layer flora.

The only attributes that continually increase with time since fire are bark and hollow development that are attributes associated with older mallee vegetation.

Nankeen Kestrel; Australian Magpie). 1 10 years post fire Chestnut Quail thrush; Tawny crowned Honeyeater; Hooded Robin; Red capped Robin; White fronted Honeyeater and Shy Heathwren become abundant. 10 30 years post fire taller and denser vegetation favours more mallee endemic birds and the density of Red lored Whistler; Crested Bellbird; Purple gaped Honeyeater and Southern Scrub robin peaks. 30 years post fire vegetation with tall mallees and relatively open understorey favours Malleefowl; Black eared Miner; White browed Babbler; Yellow Thornbill and hollow nesting birds such as Striated Pardalote and Regent Parrot start to appear.

Species dependent on larger hollows; such as Major Mitchell s Cockatoo; are expected to appear with increasing time since fire as these develop in mature trees.

Other known responses of important mallee birds to fire include (Brown et al. 2009 DEH 2009a;b Mallee CMA 2012) Chestnut Quail thrush and Shy Heathwren highest densities in sites burnt 10 years ago.

Threatened Species Scientific Committee Recent patterns of fire impacts on mallee in the MDD bioregion.

Analysis of fire history data since 1980 overlain against NVIS mallee polygons for the MDD bioregion shows how mallee vegetation and potential mallee bird habitats have been impacted by fires over the past forty years.

Fire impacts in mallee vegetation of the MDD bioregion.

Annual fire patterns show irregular major fire impacts by area and number of mallee patches burnt (Figure 7.5A).

Patterns of cumulative fire impacts may better indicate the degree to which fire impacts on mallee habitats for the bird community over a longer term.

In terms of the number of large patches burnt; the cumulative data indicates about 35 to 45 of larger patches were impacted by fire to some extent; over recent timeframes (Table 7.7B).

In terms of cumulative impacts; a lower proportion of smaller remnants are affected by fire over time (9 28 depending on timeframe); mainly due to the large number of small mallee remnants (over 6;000) present in the MDD. (Table 7.8).

In conclusion; cumulative fire impacts over the past 20 to 40 years shows that a reasonable proportion of mallee habitats may be rendered unsuitable for Mallee Birds by returning sites to early seral stages that are not preferred by several mallee birds that require mid to late stage fire succession mallee.

The impacts to regeneration may also be exacerbated when fires occur during drought and post fire recruitment is already limited by low rainfall.

Driscoll et al. s (2021) review of fire and fragmentation identified three main ways by which these two drivers and threats may interact Fire influences fragmentation by destroying habitats or creating and connecting new areas Fragmentation influences fire by suppressing it; limiting its spread or affecting flammability and ignition sources.

With regard to fire influencing fragmentation the NCAS data on transitions to non woody vegetation plus data on cumulative fire impacts across the MDD over recent decades points to a sequential transition of state within larger remnants.

The major differences between the fragmentations in conservation areas versus those in the surrounding matrix of altered land uses are cause (land clearing in the latter; fire for the former) and permanence leading to recovery potential (land clearing for agriculture constitutes a permanent change while burnt areas in conservation areas are able to recover given time and opportunity; in the form of appropriate fire intervals).

The threats of pest animals and total grazing also interact with each other; with fire and fragmentation though these may not have been quantified for the MDD.

In times and areas affected by drought; survey effort should be increased to account for the potential impacts of drought on the bird community.

The forecast over the next century is for higher weather temperatures; declining rainfall; especially in the cooler seasons; and Severity Minor to harsher drought and fire weather. date likely Major impacts in future.

Drought conditions affect reproductive performance and survival of birds; and in extreme situations will suppress breeding of some species such as Scope Whole Malleefowl and Black eared Miners.

Drought conditions will also impact the growth and survival of many plant species and consequently food availability (invertebrates and nectar).

Post fire recovery of mallee heathlands can be hampered by drought conditions.

Threatened Species Scientific Committee o Use available ecological information to avoid detrimental fire impacts on key and susceptible species in the ecological community for instance; do not burn in a way that is detrimental to long term habitat features such as mature trees. o Consider weather conditions and do not burn in or adjacent to the ecological community when soil moisture is low; or dry conditions are predicted for the coming season as flora and fauna are already stressed; recovery will be too slow and erosion may occur or weeds and pest animals become established while the vegetation cover is reduced.

The impacts to regeneration may also be exacerbated when fires occur during drought and post fire recruitment is already limited by low rainfall.