Suchergebnisse

The sensitivity of a species to 1080 poison is difficult to predict from toxicity data for other, closely related
species. LD*50s of practical use for evaluating the risk species might face from 1080-poisoning campaigns can
be obtained for untested members of some groups by the use of either values for similar species, regression
equations involving body weight, or the lower 95% confidence limits of the distribution of LD*50S of members
in each group.
Among the 171 species for which there are data there was considerable variability in the time until signs
of poisoning became apparent (0.1 h- >7 days), the time to death (0.1 h- >21 days) and the time until animals
began to show signs of recovery (2 h-18 days). Marsupial carnivores generally showed signs earlier and died
or recovered quicker than eutherian carnivores, eutherian herbivores and the marsupial herbivores of eastern
Australia, even though the last three groups have lower LD*5OS. Reptiles and amphibians generally were the
slowest to show signs of poisoning, to die or to recover, and had the highest LD50s .
All species in Australia for which toxicity data are available were ranked according to the percentage
of their body weight they would have to eat of various poison baits to receive an LD*5O. Many non-target
species require lower percentages than the target animals but the actual consumption of lethal bait may be
affected by various factors. Finally, an evaluation is given of the major groups of animals potentially most
at risk in 1080-poisoning campaigns in Australia, based on their susceptibility to 1080.

Some toxicological data are presented to show that 7 species of birds in Australia are highly sensitive to Lucijet [O,O-diethyl O-[3-methyl-4-(methylthio)phenyl] phosphorothioate], an insecticide that is used against blowflies [Lucilia cuprina], lice and keds on sheep. Data on the sensitivity of birds to fenthion (the methyl analogue of Lucijet) indicate that other species of birds in Australia could be highly sensitive to Lucijet. This is partly confirmed by the variety of species found dead where Lucijet has been used to kill animals regarded as pests (such as feral pigs). Poison 1080 (sodium fluoroacetate) is probably more effective against pigs and less hazardous to birdlife.

Birds in Australia vary greatly in their sensitivity to 1080 poison (sodium monofluoroacetate). Median
lethal doses (LD*50s) range from 0.63 mg kg-1 for red-browed firetails, Emblema temporalis, to approximately
278 mg kg-' for the emu, Dromaius novaehollandiae. Significant differences occur between the
sensitivity of different groups of birds and may be related to differences in their metabolic rates. A few
species may also have developed a tolerance to 1080 from being exposed to indigenous plants that
contain fluoroacetate, or to insects and other animals which have fed on such plants. The most common
signs of 1080 poisoning among birds are depression, fluffed feathers, a reluctance to move, and
convulsions. Signs of poisoning first appeared among the species tested at 1-60 h after dosing, and
deaths follow between 1 h to almost 11 days after dosing. The susceptibility of 48 species of birds in
Australia to 1080 poisoning is discussed in relation to typical baits and poison concentrations used
against vertebrate pests. Theoretically, fewer types of birds are likely to be at risk from dingo-poisoning
than pig-poisoning campaigns that also use meat baits but higher concentrations of 1080. Individuals of
39 out of the 48 species could be at risk from rabbit and other pig-poisoning campaigns. The impact on
bird populations will depend, among other factors, on the amount of bait individuals eat and on the
poisoning methods employed.

Acute oral LD50S (median lethal doses) and 95% confidence limits of 1080 poison for feral pigs, Sus scrofa, obtained by moving average and probit analysis methods are 1.04 (0.84-1.27) mg kg-1 and 1.00 (0.72-1.28) mg kg -1 respectively. These values are slightly higher than LD50S obtained for pigs by i/p dosing but similar to those obtained by oral dosing for other eutherian mammals. Signs of poisoning, either vomiting or increasing lethargy and laboured respiration, appeared from 1.9 to 47.3 h (median 6.2 h) after dosing, and deaths from 2.8 to 80 h (median 16.1 h) after dosing. Although 1080 is one of the most toxic poisons for pigs it has disadvantages, including the relatively large amounts that must be distributed in baits to kill pigs, and the comparatively greater susceptibility to it of many non-target birds and mammals. 36 species out of 40 non-target species likely to feed on poisoned baits are more susceptible to 1080 than pigs. Many other factors such as bait acceptance will govern what proportions of target and non-target populations will be poisoned. Attention to methods of poisoning or baiting techniques could minimize the risk that non-target animals face from pig-poisoning campaigns.

Bandicoots are more tolerant to 1080 poison than are most other mammals in eastern Australia.
LD*50S obtained for Isoodon obesulus, Perameles nasuta and P. gunni ranged from c. 5.4 to 7.7 mg
kg-1. Signs of poisoning observed were typical of those for insectivores and carnivores and first
appeared at from 2 h to over 7 days after administration ofthe 1080. Deaths occurred from 4 h to almost
9 days after dosing. To obtain a median lethal dose of LD*50 individuals of each species of bandicoot
tested would have to eat more 1080 than all the common target pests except the pig. Theoretically, they
are capable ofdoing this if the baits are poisoned carrots or pellets intended for herbivore pests or meat
baits intended for pigs. Only meat baits intended for dingoes do not appear to pose a serious
hazard.

Most rodent species that have been tested in Australia and elsewhere are highly sensitive to 1080 poison.
A few native species. particularly members of the 'pseudo-mouse group' (Conilurini), part of whose range
is in Western Australia, are much more tolerant. These species may have developed this tolerance from
being exposed to indigenous plants that contain fluoroacetate. The most common signs of poisoning
amongst rodents are depression, hypersensitivity to stimuli, respiratory distress and convulsions. Signs of
poisoning first appeared amongst the species tested in this study 0.4-38.1 h after dosing. Deaths
occurred 0.7-205.8 h after dosing. The susceptibility to 1080-poisoning of the 14 species of rodents tested
in Australia depends on both sensitivity and body size, and is discussed in relation to typical baits and
concentrations of 1080 used against vertebrate pests. Individuals of most species of rodents would appear
to face a considerable risk if pest-poisoning campaigns are carried out within their range, but the crucial
factor governing the actual effect on populations will be how many individuals find and eat the baits.

Most marsupial and eutherian herbivores that have been tested exhibit a similar high sensitivity to 1080
poison. The main exceptions are marsupial herbivore species in Western Australia, which, because of their
exposure to indigenous food plants containing fluoroacetate, have acquired a much greater tolerance to
1080. The most common signs of poisoning amongst herbivores are either hypersensitivity to stimuli or,
more frequently, lethargy, respiratory distress and finally respiratory or cardiac failure. Some species
experience convulsions, particularly just before death. Signs of poisoning amongst species tested during
this study first appeared 1.0-39.4 h after dosing. Deaths followed 3-156 h after dosing.
The overall susceptibility to 1080 of 25 species of herbivores is compared with that of the rabbit. Three
groups of marsupials are either relatively more, equally or far less susceptible to 1080 than rabbits.
Eutherians tested are also less susceptible. The actual risk an individual of each species faces during a
rabbit-poisoning campaign is also governed by other factors, particularly the amount of bait consumed
and the concentration of 1080 in the bait.

The number of common wombats can be estimated directly either by capturing every animal during a single trapping session or by mark-recapture over at least three trapping sessions. Indirect
estimates can be obtained by recording the number of burrows used every 24 h. Spotlight counts do not provide accurate population estimates.

The conc. of 1080 (sodium monofluoroacetate) in dry muscle, organs, and stomach contents of rabbits poisoned by eating baited carrots ranged from 0.004 to 0.423 mg/g. Stomach contents (mainly masticated carrot bait) and livers contained the highest concn., followed by stomach tissue, kidneys, heart, and muscle. The total 1080 content in rabbits ranged from 0.01 to 4.88 mg. The risk of secondary poisoning in animals eating rabbits poisoned by 1080 was evaluated using 2 methods. Foxes, dingos, dogs and cats probably face the greatest risk of secondary poisoning. The extent to which other carrion-eating animals, particularly birds and small dasyurids, are at risk depends on their feeding habits and wheter they are able to vomit or develop an aversion to the taste and smell of 1080. Secondary poisoning can be minimized by using the minimum effective concn. of 1080 in baits and by removing the dead animals from the treated area.

Populations of non-target birds and mammals on a semi-cleared grazing property near Braidwood,
New South Wales, did not appear to be affected by a trail-baiting campaign against rabbits, Oryctolagus
cuniculus, using pellet bait and 1080 poison. Rabbit numbers were reduced by about 90% and those
of the fox, Vulpes vulpes, another exotic pest, by about 75%. Populations of both pest species began
recovering soon after the campaign, indicating the need for continued control measures.

A week-long hunting trial with dogs, Canis familiaris, to control feral pigs, Sus scrofa, in Namadgi
National Park, A.C.T., did not cause the pigs to disperse from the area or adversely affect the success
of two subsequent poisoning exercises. Hunting was generally not as effective in reducing pig numbers
as poisoning with warfarin, but could be useful for obtaining samples of pigs for monitoring disease
during the first few days of an exotic disease outbreak, and also for killing pigs that have survived
other control methods.

Analysis of faeces deposited by common wombats (Vombatus ursinus) in native eucalypt [Eucalyptus spp.] forest and pine (Pinus radiata) plantations of various ages in New South Wales, shows that grasses are the dominant food eaten in both forest types regardless of the varying availability of this type of vegetation. Other vegetation, such as rushes, bark, roots and pine needles, are also eaten, particularly in areas where grasses are less common.

Both fermenting wheat and bran/pollard pellets were readily accepted as bait throughout the year by feral pigs (Sus scrofa) in Namadgi National Park, Australian Capital Territory. Birds mainly ate wheat bait, particularly during winter. Other animals occasionally fed on both types of bait, mainly during autumn and winter. Covering baits with forest-floor litter did not significantly affect their discovery and consumption by pigs or by other animals. The proximity of the pigs to the bait line and their appetite for bait appeared to be the main factors responsible for seasonal differences in bait consumption. Trail-baiting campaigns against pigs in similar hill country areas are likely to be more effective during late autumn than other seasons because more pigs are likely to be close to the trails then and more quickly find and eat greater quantities of bait.