Review of the management of feral animals and their impact on ...

In truth, camels do substantial damage to natural areas, <strong>and</strong> <strong>the</strong>y are multiplying
rapidly. In 1969 Australia’s camel population was estimated at 20,000. In 1995 it was
thought to be ‘up to 100 000’ (Dörges & Heucke 1995). It is now estimated at
740,000 (Edwards et al. 2003). The Nor<strong>the</strong>rn Territory camel population more than
doubled between 1993 <strong>and</strong> 2001 <strong>and</strong>, if not controlled, will double again in about
eight years (Edwards et al. 2003).
There is strong anecdotal evidence to show that camels alter vegetation communities
by selectively browsing <strong>and</strong> removing plants; <strong>and</strong> that camels deplete <strong>and</strong> despoil
scarce water supplies in remote deserts.
Browse certain plants
Because camels rarely need to drink, do not graze intensively around waterholes, are
confined to remote regions, <strong>and</strong> are seldom seen by most Australians, <strong>the</strong>ir grazing
<strong>impact</strong>s were long discounted. But camels selectively target certain plants <strong>and</strong> certain
habitats, <strong>and</strong> <strong>the</strong> damage <strong>the</strong>y do, although selective, can be severe.
Robinson et al. (2003) note:
‘…some plant species appear to be singled out by camels as dietary
favourites. Most seriously affected among <strong>the</strong>se are <strong>the</strong> qu<strong>and</strong>ong [Santalum
acuminatum], plumbush [S. lanceolatum] <strong>and</strong> desert kurrajong [Brachychiton
gregorii], which <strong>the</strong> camels break branches from to access even <strong>the</strong> highest
leaves, <strong>of</strong>ten leading to tree death.’
Dörges <strong>and</strong> Heucke (2003) note heavy browsing <strong>of</strong> qu<strong>and</strong>ongs along with curly-pod
wattle (Acacia sessiliceps) <strong>and</strong> <strong>the</strong> coral tree (Erythrina vespertilio), with plumbush
(S. lanceolatum) <strong>and</strong> supplejack (Ventilago viminalis) also placed under heavy
pressure.
The desert qu<strong>and</strong>ong was recently listed as a vulnerable species in <strong>the</strong> Nor<strong>the</strong>rn
Territory, <strong>and</strong> camels pose <strong>the</strong> main threat to its survival. Curly-pod wattle is also rare
(Dörges & Heucke 2003). Qu<strong>and</strong>ongs bear an edible fruit, <strong>and</strong> <strong>the</strong>y are valued by
indigenous communities both as a food source <strong>and</strong> spiritually. The fruits are an
important food <strong>of</strong> emus <strong>and</strong> <strong>the</strong> seeds are eaten by rodents. Qu<strong>and</strong>ong stems are brittle
<strong>and</strong> <strong>the</strong>y do not resprout after camel breakage (P. Copley pers. comm.).
Dörges <strong>and</strong> Heucke (2003) noted substantial browsing on two Lawrencia species <strong>and</strong>
suggested that rare Lawrencia species would be expected to suffer from camel
browsing. As noted above, <strong>the</strong>y suggest that camels could contribute to <strong>the</strong> extinction
<strong>of</strong> rare plants. The diets <strong>of</strong> camels overlaps heavily with those <strong>of</strong> livestock <strong>and</strong>
kangaroos, but <strong>the</strong> differences can be highly significant. Dörges <strong>and</strong> Heucke (1995)
note that <strong>the</strong> camel, ‘can utilise thorny, bitter <strong>and</strong> even toxic plants that are avoided by
o<strong>the</strong>r herbivorous mammals.’ They can also reach much taller foliage. They can eat
more than 80 per cent <strong>of</strong> <strong>the</strong> plant species <strong>the</strong>y have access to, including more than
340 plant species (Dörges & Heucke 2003).
Camels were thought to be important competitors <strong>of</strong> <strong>the</strong> endangered Rufous harewallaby
before it became extinct in <strong>the</strong> Nor<strong>the</strong>rn Territory (Lundie-Jenkins et al.
1993), eating <strong>the</strong> same foods, <strong>and</strong> also denuding <strong>the</strong> vegetation used by hare-wallabies
for shelter.
Camels contribute to l<strong>and</strong> degradation indirectly, by breaking down fences that are
meant to keep rabbits <strong>and</strong> livestock out <strong>of</strong> sensitive areas. Camels are powerful
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