Download Birds Australia Wingspan Supplement 7 Fire and Birds

6
Fire and Birds
Fire and Birds
Towards a set of biodiversity-friendly fire management principles
South-eastern Red-tailed
Black-Cockatoos and Fire
The endangered South-eastern Red-tailed BlackCockatoo is a dietary specialist; it eats only the
seeds of three tree species—Brown Stringybark,
Desert Stringybark and Buloke. Supplies of these
seeds are patchy in space and time, and flocks tend
to concentrate on the seed stocks that can be most
efficiently harvested. There is mounting evidence
that cockatoo breeding success is related to the
availability of fresh stringybark seed crops.
The stringybark forests of south-western
Victoria are highly flammable and the heathy
understorey requires fire to maintain its floristic
diversity. However, fires that burn or scorch the
canopy result in reduced seed production for up to
nine years. Therefore, the widespread burning of
stringybark forests through the twentieth century
may have been a cause of population decline in
the Red-tailed Black-Cockatoo. With this in mind,
a moratorium on burning was imposed in 1989.
However, there are now good ecological and asset
protection reasons for resuming planned burns.
In an attempt to resolve this impasse, the
Department of Sustainability and Environment,
with the support of the recovery team, has
trialled methods of burning the understorey while
minimising canopy scorch. This is a tall order in
stringybark forests, where the fibrous bark tends
to carry flames upwards. However, given the right
conditions of fuel moisture and weather, the trials
are suggesting that ecological burning aims, or asset
protection aims, can be met whilst minimising the
impact on future crops of stringybark seed.
PETER MENKHORST AND JIM MCGUIRE, Department
of Sustainability and Environment, Victoria
Australia is a large and diverse country, hence
there are many views and requirements for
biodiversity-friendly fire management. The
following are some of several recommendations
in the literature:
• Encourage precautionary fire management.
• Be aware that fire regimes need to be local and
focus on particular objectives.
• Wherever possible develop guidelines and
prescriptions for landscapes and biological
communities, not individual plants and
animals.
• However, where there are species or groups of
species that are susceptible to decline under
certain fire regimes, fire management regimes
should be framed around their needs.
• Aim for fire management targets that are
ranges rather than optima; for example, rather
than choosing the best time for one species
pick a range of times and fire intervals that
cover several species.
• Avoid fire regimes known or suspected to result
in loss of biodiversity in the same or related
ecosystems.
• Be aware that fire frequency is a key element of
fire management—with few exceptions both
fire exclusion and short intervals between fires
over a broad area are damaging to biodiversity.
• Similarly, broadscale, intense fires are
damaging to heterogeneity of habitats
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across the landscape, and hence to
biodiversity values.
Hence, aim to reduce the extent of land/
proportion of vegetation community burned
in single-fire events, no matter what time of
year that happens.
Use fire at a small scale to promote spatial
and temporal variability in fire regimes across
the landscape, that is, a patchwork of areas of
different fire-ages and histories.
Understand that fire-generated patchiness
is good but must be at the right scale (for
example, in relation to the species being
managed or the size of the remnant).
Develop prescriptions to limit the extent and
spatial invariability of fires by controlling fire
behaviour, rather than by imposing artificial
exclusion zones and intervals between fires.
Accept that there will always be gaps in
knowledge, which introduce an element of
uncertainty in the decision-making process.
Allow for unplanned fires.
Climate change means that the country is
likely to be entering a period of hotter, drier
conditions, which will produce more extreme
fire events, which will need to be factored
into management.
Apply adaptive management, including
monitoring, to inform decisions and
improve management.
Threatened birds and fire regimes. This table presents some simple rules for bird-friendly fire management1.
Local conditions and threatened species should be used as a finer guide to management.
To burn or not to burn
Fire regimes result from complex interplay
between biotic (e.g. fuel loads) and abiotic factors
(e.g. weather conditions), increasingly overlaid
with human decisions in support of a variety of
land uses, including biodiversity conservation.
Land managers must weigh up these factors to
estimate the threat from uncontrolled fire and the
desirability of a controlled burn.
contours
slope
fire history
vegetation
land cover
fuel loadings
McArthur
Fire Model
Main
habitat
Threatened species for which
inappropriate fire management is a threat2
Current general fire problem
for bird conservation
Fire management for bird
conservation
Coastal and
sub-coastal
shrublands
Orange-bellied Parrot CE
Ground Parrot (eastern) V
Ground Parrot (western) CE
Rufous Scrub-bird (northern) V
Noisy Scrub-bird V
Southern Emu-wren (Fleurieu Peninsula) CE
Southern Emu-wren (Eyre Peninsula) V
Eastern Bristlebird (northern) CE
Eastern Bristlebird (southern) E
Western Bristlebird V
Rufous Bristlebird (Otways) V
Western Whipbird (western heath) V
Too frequent burning;
too coarse a mosaic.
Pattern: Fine mosaic of areas of
different fire-ages with a bias towards
retention of older fire ages.
Intensity: Low.
Mallee
Malleefowl V
Mallee Emu-wren V
Black-eared Miner E
Western Whipbird (eastern) E
Fire management (prescribed
burns or Aboriginal burning
regimes) has been much
reduced so that wildfires are
too hot and extensive.
Pattern: Mosaic of areas of different
fire-ages with a bias towards
retention of older fire ages. Fire
frequency at most every 40 years in
any particular area.
Intensity: Low.
Temperate
eucalypt
open forests
Red-tailed Black-Cockatoo (south-eastern) E
Glossy Black-Cockatoo (Kangaroo Island) E
Helmeted Honeyeater CE [riparian]
Forty-spotted Pardalote E
Fire exclusion.
Pattern: Mosaic of fire-ages across
the landscape with a bias towards
retention of older fire ages.
Intensity: Flexible use of a broad
range of fire regimes.
Tropical and
sub-tropical
forests/
rainforest
Southern Cassowary V
Red Goshawk V
Black-breasted Button-quail V
Masked Owl (Tiwi Islands) E
Fire exclusion permits spread
of fire-sensitive species.
Pattern: Mosaic of fire-ages across
the landscape with a bias towards
retention of older fire ages.
Intensity: Occasional hot burns.
Tropical and
sub-tropical
savanna
woodlands
and
grasslands
Buff-breasted Button-quail E
Partridge Pigeon (western) V
Golden-shouldered Parrot E
Paradise Parrot Ex
Night Parrot CE
Hooded Robin (Tiwi Island) V
Crested Shrike-tit (northern) E
Gouldian Finch E
Star Finch (Cape York) E
Fires now too hot, extensive
and frequent, or, alternatively, too infrequent.
Pattern: Fine-scale mosaic of
fire-ages across the landscape,
with between 10 and 30% of
landscape burned each year.
Intensity: Occasional hot burns.
Wetlands
Australian Bittern (Australasian) V
Burning of habitat to create
pasture.
No prescribed burns.
standard fuel &
weather conditions
Hazard
structures
roads and trails
residential
Risk
revegetation
residential
structures
constructed
values
fauna values
flora values
natural
values
Risk/Hazard
matrix
Values
Threat
One approach to the prediction of the threat of fire.
Source http://www.planning.sa.gov.au
1Based
on information in Woinarski (1999) www.deh.gov.au/biodiversity/publications/technical/fire/
from Garnett & Crowley (2002). Categories of threat in decreasing order of severity: Ex = Extinct;
CE = Critically Endangered; E = Endangered; V = Vulnerable; subspecies name in brackets. Twenty-two other species
are listed as Near Threatened, and inappropriate fire regimes are among their major threats.
2Extracted
7
LIVING WITH FIRE—BIRDS
IN NORTHERN AUSTRALIA
Australia’s north is a landscape of fire, and some naive
ideal of fire suppression and exclusion will neither
work nor suit most bird species
by John Woinarski
Climatic conditions, vegetation, social factors and human population
dispersion cause fire to be a very different phenomenon in northern
Australia to that elsewhere in the continent. The north is monsoonal,
with a strongly seasonal climate marked by a long, almost rainless,
warm dry season (typically from about April to October), and a strongly
contrasting hot wet season.
Fire is an inevitable part of this landscape. The dense, tall grasses grow
rapidly over the short wet season, and then dry out over the long dry season,
becoming highly flammable. Without human intervention, this vegetation
burns readily with ignition from lightning strikes, a characteristic feature of
the first thunderstorms that mark the transition from the dry to the wet.
Humans have long been moulding this landscape. For the Indigenous
people fire has been a crucial part of life and their main management tool
for 40,000 years or more. Such application of fire was far from reckless.
The consequences of ill-advised fire management were severe: vital food
sources could be eliminated through inappropriate fires, and fires that
spread to burn neighbouring clan estates could invite retribution. In parts
of northern Australia this tradition continues. In these areas, the application
of fire may be a highly skilled and carefully considered operation, carried
out diligently throughout the year. Typically, this traditional management
involves many small ‘cool’ fires, producing an intricate network: a fine-scale
mosaic of unburnt patches and patches burned at different times through
the year. Often, the more fire-sensitive components of the landscape—such
as rainforest patches—were explicitly and deliberately protected from fire,
typically by burning around their margins. These elements were valued
because they produced important foods, particularly yams, in traditional
diets; and the maintenance of such fire-sensitive elements in a clan estate
was a sign of proper management.
Over the last century, traditional Indigenous fire management in
most of northern Australia has broken down. Indigenous people were
dispossessed from much of the landscape. Even in lands that maintained
Indigenous ownership, population dispersion and lifestyles changed. In the
decades around the Second World War, most of the population moved off
their clan estates to live at mission stations and other townships. In some
areas, this dynamic has been reversed through the ‘outstation movement’,
beginning in the 1970s. But, over most of northern Australia, traditional
burning has been disrupted and replaced by very different fire regimes.
Below left: With less than 50 known individuals the Eastern Bristlebird (northern
subspecies), of Cooloola National Park and the Conondale Ranges, Queensland,
is critically endangered. Its main threat is changed fire regimes, with fire now too
frequent, destroying the species’ tussock grass habitat, or too infrequent, allowing
shrubs to become too dense. Below: Fires remove dense ground cover to expose
seeds on which the finches feed, but may also destroy wet season food species,
and nests. Here a Masked Finch collects charcoal for its nest (presumed to help
keep the nest dry and sanitised). Photos by Graeme Chapman
Wildfire at Kakadu National Park, Northern Territory. Photo by Raoul Slater
Fuelling fire
The current fire regimes vary somewhat between tenures. On pastoral
lands, which occupy about half of northern Australia, fire is generally
unwanted and suppressed—livestock consume most of the grassy fuels,
so that fire behaviours and intensities are now different to those that
prevailed over tens of thousands of years. Partly because of the reduced
incidence of fires, vegetation in many pastoral areas is changing, often
with increases in the density and extent of woody shrubs and decrease in
grassland areas (‘vegetation thickening’). Fires on other tenures are now
characterised by an increased incidence of late dry season burns, and these
are typically more intense and extensive. The previous fine mosaic of
patchy burnt and unburnt areas has been replaced by broad-scale conflagrations that homogenise the landscape. Far more often than previously,
these fires engulf the fire-sensitive elements of the landscape.
Superimposed on this change in fire regimes is the consequence of
the increasing and largely uncontrollable spread of African and South
American pasture grasses, deliberately introduced by pastoralists and
pasture scientists to transform (‘improve’) the landscape. This insidious
set is marked by their ability to dominate almost every environment in
northern Australia, including wetlands (Para Grass, Olive Hymenachne),
tropical open forests and savanna woodlands (Gamba Grass, Mission
Grass, Guinea Grass) and semi-arid woodlands (Buffel Grass). The
replacement of native understoreys by introduced pastures is itself an
ecological wound but, worse, these grasses also greatly alter fire regimes.
Largely because they are voracious consumers of soil nutrients, exotic
grasses produce fuel loads that are far greater than native grasses (up to
seven times the biomass), and they typically cure later in the dry season.
This inevitably means that fires fuelled by exotic, invasive pastures
are more intense (up to 10 times hotter) than fires with native grass
understoreys. Whereas previously fires in northern Australia burned the
grassy understorey and rarely affected the tree layer, exotic grasses are now
fuelling crown fires that kill the tree layer.
Currently, fires burn about 30–50% of northern Australia each year.
Many areas have been burnt every year over the last decade. The scale and
recurrence of fires is vastly different to southern Australia. In extent, the
regular fires of northern Australia dwarf the bushfires in south-eastern
Australia, such as Ash Wednesday and those in the south-east highcountry in 2003. For example, in five days of October 2004, a fire in
the Sturt Plateau and northern Tanami Desert of the Northern Territory
burned out an area greater in size than Tasmania, but didn’t even make
headlines in the local newspapers.
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Fire and Birds
Fire and Birds
9
Long-term impacts on birds
Above: The threatened White-throated Grasswren occurs only on and around the Arnhem Land escarpment
where frequent hot fires are causing spinifex to be replaced by annual sorgum. Photo by Graeme Chapman
Below right: Partridge Pigeons (here the yellow-faced Kimberley race) persist in areas where a mosaic of
fire ages has been maintained; the western subspecies is threatened, but the eastern subspecies is faring
better where traditional burning regimes have continued. Photo by Jiri Lochman, Lochman Transparencies
Short-term impacts on birds
So, how do birds in northern Australia fare
with fire, and how have recent changes in
fire regimes and management affected birds?
There is substantial variation among
the bird species of northern Australia in their
immediate responses to fire, and in their
longer-term responses to fire regimes. Many
bird species are attracted to burning and
recently burnt areas. The most conspicuous of
the immediate responders are raptors—particularly Whistling Kites, Black Kites and Brown
Falcons—which hunt, sometimes in very
large numbers, among the flames of the fire
front for fleeing large invertebrates and small
vertebrates. These birds may not only benefit
directly from fires, but may also be firebugs
themselves—there are many reports of kites
spreading fires by snatching up burning sticks
and dropping them ahead of the flames. This
attraction of raptors to fires was used by some
Aboriginal hunters, who built elaborate rock
hides in which they lit smoky fires and waited
to grab or spear hawks that came close to
investigate. Other birds attracted to the fire
front include woodswallows and swifts which,
like the raptors, may make regional-scale
movements tracking the fires.
Even the relatively slow and cool
burns of the early dry season may kill some
invertebrates and small vertebrates, and
many birds are attracted to the carrion in the
immediate aftermath of fires. These include
butcherbirds, Australian Bustards, crows, ibis,
Magpie-larks and kingfishers. As with the
raptors, some of these birds may undertake
regional-scale movements from one recently
burnt area to another. Fires provide benefit
not only for carrion-eaters, but also to a wide
range of terrestrial species. When unburnt,
the dense tall grasses of northern Australia
may be a major impediment to foraging for
many bird species. The cool fires of the early
dry season remove this barrier, but typically
do not greatly reduce the density of invertebrates or seeds lying dormant on the soil
surface. Thus, recently burnt areas attract a
very wide range of seed-eating birds, typically
including Red-tailed Black-Cockatoos,
Galahs, Cockatiels, Little Corellas, Peaceful
Doves, Diamond Doves, Partridge Pigeons
(or their near equivalent, Squatter Pigeons,
in Queensland), and a multitude of finches.
The open ground layer makes for easier
foraging for insectivores and carnivores, such
as Hooded Robins and butcherbirds.
Of course, not all is for the best. Certain
species, such as Red-backed Fairy-wrens and
some quails, need the dense grass layer for
shelter and nesting; and will suffer greatly
increased predation rates in recently burnt
areas. In a delicate balancing act, some bird
species need both burnt and unburnt areas.
For example, in the early dry season, Masked
Finches and Partridge Pigeons nest on or
near the ground. Fires at such times are likely
to destroy many nests, and, for Partridge
Pigeons at least, nest predation rates are likely
to be much lower where their ground nests
are at least partly sheltered under grass cover.
But these birds will struggle to access enough
food over the course of the dry season if
their territories are completely unburnt. The
optimum fire regime for such species is one
of very fine-scale intricate burning, where
each year part of the territory or home range
is burnt and part unburnt. Such a regime
requires fire patches at about a hectare
scale. This pattern of burning is no longer
prevalent in northern Australia. Rather, the
current regime is characterised by burnt and
unburnt areas in patches of tens to hundreds
of square kilometres.
Birds respond not only in the short-term to
individual fires, but also over the longer-term
to the patterned history of burning over many
years. In parts of temperate Australia (such as
in the mallee, coastal heaths and mountain
forests), this is a sharply etched response, as
there may be a conspicuously contrasting
vegetation succession over the multi-decade
interval between fires. The vegetation response
to fire regimes in northern Australia is typically
more nuanced. The relatively few long-term
studies—that typically describe experimental
situations where great efforts must be made to
exclude fires for any length of time—suggest that
there is relatively little, or slow, change in plant
species composition with increasing time since
fire. However, protection from fire does lead to
a substantial structural change in vegetation.
When an area is unburnt for five or more years,
instead of the very simple vegetation profile of
trees and grass that characterises most northern
Australian forests, a diverse shrubby mid-storey
develops, and continues to increase in height,
cover and diversity with increasing duration since
fire. Correspondingly, with increasing shading,
the grass layer diminishes. These vegetation
changes inevitably favour some bird species
and disadvantage others. Many of the shrubby
plants produce (very tasty) fleshy fruits, and the
increasingly dense mid-storey provides good
nesting sites and an increased foraging resource
for some insectivorous birds. Birds that occur in
greater abundance in such relatively long-unburnt
areas include White-throated Honeyeater, Dusky
Honeyeater, White-gaped Honeyeater, Northern
Fantail, Weebill, Lemon-bellied Flycatcher, and
Bar-shouldered Dove. Conversely, birds such as
butcherbirds, kingfishers and Red-backed Fairywrens, that prefer the simpler structure of trees
and grass, are markedly less abundant in areas
long untouched by fire.
Over the long period, fire regimes change
not only the vegetation profile within any patch,
but also the borders between—in doing so they
alter the relative extent of different vegetation
Left: A change in fire regime threatens the
eastern Spinifex Pigeon. Photo by Jonathan
Munro, www.wildwatch.com.au
Below: Late dry season fires which burn the
fringes of gallery rainforest and paperbark
thicket can destroy large trees with holes for the
Rufous Owl and its prey species, including the
Brush-tailed Possum. Photo by Jonathan Munro,
www.wildwatch.com.au
types. In northern Australia, frequent fires will
generally favour expansion of grasslands, and
reduction in fire frequency will favour increases
of woody vegetation. On pastoral lands of
Cape York Peninsula, a reduced frequency
of fires has led to invasion of grasslands by
paperbarks (Melaleuca), substantially reducing
the area of suitable habitat for the endangered
Golden-shouldered Parrot. Conversely, the
grass-wrens of sandstone escarpments in
northern Australia (the Black, White-throated
and Carpentarian) are now all threatened by a
fire regime that is too frequent, and eliminates
the large old clumps of spinifex (Triodia)
that these species require. Acacia-dominated
woodlands (the ‘pindan’ of the Kimberley and
lancewood in the Northern Territory and parts
of central Queensland) are also being eroded by
the increasing frequency, intensity and extent of
fires, to the detriment of birds such as Hooded
Robin and Grey-crowned Babbler. Other
fire-sensitive vegetation in northern Australia
includes rainforests and heathlands, and these
may also be under some threat from increasingly
frequent fire.
Accepting a fiery future
Over tens of thousands of years, the fire
regimes of northern Australia were actively
and consistently managed. This produced
some (not necessarily ideal) sort of
equilibrium and reasonable stability in the
vegetation patterning, and hence bird species
composition. Over the last century (in many
areas, over the last few decades), that longestablished fire regime has come to a halt,
and in its place is an erratic, inconsistent
and far less knowledgeable management
of fire. This change has destabilised that
equilibrium. As a result, some species will
increase and some will decrease. Some of the
decreasers are likely to suffer at least regional
extinctions.
The conservation and management
challenge in northern Australia is profound.
It is a landscape of fire, and some naive ideal
of fire suppression and exclusion will neither
work nor suit most bird species. Fortunately,
there remain some areas where traditional
Aboriginal management of fire is practised,
and we still have the opportunity to learn
from this expertise. One priority is to provide
support for the nascent ranger schemes that
have sprung up on some Aboriginal lands,
to help get Aboriginal people back onto and
managing their estates.
Another priority is to develop far better
regulation of the use of exotic pasture grasses.
Currently, there are almost no limitations on
the deliberate spread of these weedy species
on pastoral lands. Rather, it is typically
encouraged, and there is a largely passive
acceptance by most regulatory authorities of
the grasses’ inexorable spread from pastoral
properties to neighbouring Aboriginal and
conservation lands. Another priority is to
improve understanding of the role of fire in
northern Australia. Bushfires in southern
Australia tend to be infrequent, ‘destructive’
and shocking: for a short time at least they
concentrate the mind. In northern Australia
they are so much a part of the landscape that
they are accepted blithely. Their environmental impact is far more subtle and gradual
than in the south, and hence we are less
driven to think about their role. But ecology
and conservation can be undermined as
much by repeated subtle and insidious factors
as by occasional showy episodes.
John Woinarski works as Principal Research
Scientist for the Northern Territory’s Department
of Infrastructure, Planning and Environment,
and is engaged in a broad range of research
projects including wildlife survey, conservation
planning, ecological studies of threatened animal
species and the impacts of fire and pastoralism.