Threatened Species of the Northern Territory
DESERT SAND-SKIPPER
Croitana aestiva
Conservation status
Australia: Endangered
Northern Territory: Near Threatened
Photo: C. Palmer
Description
The Desert Sand-Skipper is a small brown
butterfly with pale yellow markings. It has a
wingspan of about 22 mm. Like other
members of the skipper family, the clubs of
the antennae are sharply bent near their base.
Distribution
The Desert Sand-skipper is endemic to the
Northern Territory (NT), known only from the
MacDonnell Ranges Bioregion. Recent
surveys have revealed 13 extant populations,
and covering approximately 1400 km 2. No
desert sand-skippers have been located
recently at one of the historic sites (Larapinta
Drive, 25 km West of Alice Springs) but the
larval food plant does not occur there and it is
likely that the species is not permanently at
this site. It is likely that the roadside record
there from 1966 is a result of a very large
emergence of adults from an, as yet
undiscovered, patch of habitat in the hills
nearby (C. Palmer pers. comm.). The
distribution of butterflies is determined to a
large extent by the distribution of the larval
food plant (the grass Neurachne tenuifolia)
which is restricted to the West MacDonnell
Ranges, where it is found in sheltered slopes
and gorges as far west as Mt Liebig (260 km
West of Alice Springs). As the grass is found
For more information visit www.denr.nt.gov.au
fairly continuously through the Chewings and
Heavitree Ranges, one can assume that C.
aestiva is also fairly continuously distributed
through these ranges.
Conservation reserves where reported:
Owen Springs Reserve and West MacDonnell
National Park.
Known locations of the Desert Sand-Skipper
Ecology
Chris Palmer recently identified the larval
food plant; the grass Neurachne tenuifolia. He
has also shown that adult emergence and
abundance are entirely dependent on rainfall,
such that adults will not emerge without
adequate rain, and larger numbers of adults
are seen following wetter periods. Systematic
and comprehensive counts of adults following
rain have been conducted at Standley Chasm
since re-discovery of the species, and up to
80 adults have been observed at that site at
any one time.
Conservation assessment
Previous assessment of the conservation
status of this species was based on a very
small number of records and the species not
having been observed for more than 30 years.
Now, the species is known from at least 13
locations and much more is known of the
species’ ecology.
Although the butterfly has a limited spatial
distribution and is ecologically specialised,
there is no evidence of decline, either
observed or inferred. Most of the known
localities show evidence of some disturbance
(Palmer 2010) but this has apparently had
only little or no impact on butterfly
populations. There is currently no risk of
extinction of this species. Thus, the
conservation status of this species
approaches Vulnerable (under criteria B1+B2)
based on:
•
Extent of occurrence <20,000 km 2;and
•
Area of occupancy <2,000 km 2.
However the species is known from more
than ten locations, is not severely fragmented
and does not experience extreme fluctuations
in numbers or distribution. As a consequence,
the species is listed in the NT as Near
Threatened.
Threatening processes
and altered fire regimes are of most
importance to the species.
Buffel Grass, Cenchrus ciliaris, is a very
invasive species in Central Australia forms
dense monocultures and competes with,
eventually displacing, native plant species,
particularly grasses (Clarke et al. 2005).
The increased biomass in the high density
monocultures results in high fuel loads,
resulting in increases in the frequency and
intensity of fire.
Conservation objectives and
management
There is a national recovery plan for this
butterfly (Palmer 2010).
Research priorities are to:
i.
ii.
iii.
undertake surveys elsewhere in the
MacDonnell Ranges to search for
additional populations , especially
areas occupied by the larval food
plant;
investigate the basic biology and
ecology of the species to determine
more precisely the habitat
requirements; and
establish a monitoring program to
detect possible changes in range or
abundance, and to measure the
impacts of threatening processes.
Management priorities are to:
i.
ii.
control the spread of Buffel Grass; and
maintain appropriate burning practices
in locations where populations are
found.
The larval food plant of this butterfly species
is probably intolerant of fire (Prendergast and
Hattersley, 1985), and the habitats in which it
occurs are surrounded by open plain areas
very exposed to bushfires. Consequently, the
inter-related threats of invasive grass species
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Complied by
Chris Palmer
Michael Braby
Colin Wilson
Chris Pavey
Simon Ward
[updated December 2012]
References
Clarke, P.J., Latz, P.K., and Albrecht, D.E. (2005). Long
term changes in semi-arid vegetation: invasion of
an exotic perennial grass has larger effects than
rainfall variability. Journal of Vegetation Science 16,
237-248.
Palmer C.M. (2010). National Recovery Plan for the Desert
Sand-skipper Croitana aestiva. (Department of
Natural Resources, Environment, The Arts and
Sport, Northern Territory, Alice Springs).
Prendergast, H.D.V. and Hattersley (1985). Distribution
and cytology of Australian Neurachne and its allies
(Poaceae), a group containing C 3 , C 4 and C 3 -C 4
intermediate species. Australian Journal of Botany
33, 317-33
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