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1080 aerial baiting for the control of wild dogs and its impact on spotted-tailed quoll (Dasyurus maculatus) populations in Eastern Australia
Abstract
To further investigate the non-target impact of baiting using sodium monofluoroacetate (compound 1080) to control wild dogs, a population of radio-collared spotted-tailed quolls was subject to an experimental aerial baiting exercise. The trial was conducted at a site on the New England Tablelands, New South Wales, without a recent history of that practice. Sixteen quolls were trapped and radio-collared before baiting. Fresh meat baits were delivered from a helicopter at a rate of 10-40 baits km-1. In addition to 1080 (4.2 mg), each bait contained the bait marker rhodamine B (50 mg), which becomes incorporated into growing hair if an animal survives bait consumption. Two quoll mortalities were recorded following aerial baiting. Both quolls died 3-5 weeks after baiting when baits, on average, retained little 1080. None of the carcasses contained traces of 1080, but the test result is less reliable for the quoll that was found 19 days after its death although tissue was well preserved because of the cool weather. Nevertheless, given that this animal died 34 days after bait delivery, it appears likely that none of the radio-collared quolls succumbed to baiting. In contrast, vibrissae samples collected from 19 quolls captured after the baiting showed that 68% had eaten baits and survived. Furthermore, multiple bait takes were common, with up to six baits consumed by one female. The results demonstrate that most, if not all, quolls survived the baiting trial, including those that consumed dog baits. Hence bait consumption figures per se are not indicative of mortality rates attributable to poisoning.
... Much attention has been directed towards the potential non-target impacts of 1080 poison baiting for wild canids on a range of native mammal species in Australia, particularly most-at-risk carnivores such as the spotted-tailed quoll (Dasyurus maculatus) that are known to scavenge as well as take live prey (i.e. Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007). The spotted-tailed quoll is listed as a threatened species at both State and Commonwealth levels in Australia. ...
... The implied collapse of the study populations of Belcher (2003) is in marked contrast to results obtained from a series of studies where the fate of radio-collared spotted-tailed quolls has been followed during 1080 baiting events for wild dog control. These studies collectively show that while quolls clearly encounter and consume baits, they seldom die from those baits (Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007;Cremasco and Selles 2008). This finding has been consistent irrespective of the dosage rate of 1080 in baits (3-6 mg) as well as the rate at which 1080 baits have been deployed (2-40 baits km À1 ). ...
... This finding has been consistent irrespective of the dosage rate of 1080 in baits (3-6 mg) as well as the rate at which 1080 baits have been deployed (2-40 baits km À1 ). Furthermore, through use of non-toxic biomarkers such as rhodamine B, it is also clear that individual quolls may survive consuming multiple baits (Claridge and Mills 2007;Körtner 2007). ...
ContextOutside its breeding season, the marsupial carnivore the spotted-tailed quoll (Dasyurus maculatus) is apparently largely unaffected by aerial baiting for dingoes and other wild dogs (Canis familiaris). However, the potential impact of aerial baiting during spring on female spotted-tailed quolls carrying and weaning young remains unquantified. Aim The survivorship of female quolls and their pouch young was investigated after aerial baiting at two sites representing the northern and southern part of their New South Wales range. The null hypothesis was that aerial baiting would not lead to direct mortality of any adult females or higher pouch young mortality over that reported in the published literature under normal conditions. Methods In total, nine female quolls with pouch young and eight male quolls were trapped, fitted with GPS/VHF collars containing mortality sensors and released at their point of capture. After trapping ceased, meat baits nominally containing 6mg of 1080 and 50mg of the biomarker rhodamine B were deployed by helicopter at both sites at the maximal permissible rate of 40 baits km−1. We monitored collared quolls daily for 4–5 weeks for mortality then retrapped animals and sampled whiskers for evidence of the biomarker. The fate of pouch young was also followed throughout our study by examining pouches of adult females and camera trapping at maternal den sites. Key Results No collared quolls died. After the daily monitoring period, 10 quolls, including all six collared female quolls, were trapped at the southern site, and whisker samples taken and assayed for Rhodamine B. Seven (4 females and 3 males) tested positive for rhodamine B, indicating consumption of baits. Separate bands of the biomarker in whisker samples indicated that most animals that tested positive had been exposed to multiple baits. At the northern site, four quolls (including two females and two males) tested positive for rhodamine B from the nine sampled. Post-baiting inspection of pouches of all trapped adult female animals, together with camera trapping at den sites, showed that the development of pouch young was unaffected by the baiting. Camera trapping arrays set across both sites continued to record the animals that were exposed to baits well beyond the baiting events, including evidence of breeding in a subsequent season. Conclusion Our aerial baiting programs had no observable impact on the collared female quolls, or their ability to raise and wean young. These findings are consistent with results from all previous field-based experimental studies, which show no population-level impacts of 1080 baits on spotted-tailed quolls. Implications Land managers should not be concerned about impacts of aerial baiting for wild dogs on spotted-tailed quolls, either in autumn or in spring during the breeding season.
... The use of 1080 canid baits is considered safe for many nontarget native species in eastern Australia (e.g., Körtner, 2007); however, the smaller bait size, higher application rates, and increased palatability of 1080 feral cat baits (such as Eradicat and Hisstory) present a different risk profile for nontarget species. For example, fox and wild dog baiting programs in eastern Australia typically use large bait sizes (~125-250 g), thereby reducing the chance that small nontarget mammals and birds could handle, move, or eat an entire bait (Gentle et al., 2014). ...
... Other factors, including the relative palatability of bait to each species, availability of bait and alternative foods, the amount of bait and toxin ingested by each individual, and variation in individual susceptibility to the toxin, may all influence the probability of mortality . For example, labderived sensitivities suggest that spotted-tailed quolls (Dasyurus maculatus) are at theoretical risk of mortality from 1080-based wild dog baits , however field assessments have found that quolls consume 1080 wild dog baits and survive, with some quolls surviving after eating multiple baits and consuming in excess of the theoretical lethal dose of 1080 (Körtner, 2007). Alternatively, species considered to be at theoretical risk of mortality might not encounter enough baits in the landscape or might not consume the baits they do encounter. ...
Feral cats pose a significant threat to wildlife, agriculture and human health through predation, disease transmission and competition with native animals. Controlling feral cats and their impacts, however, is challenging. New and emerging 1080‐based feral cat baits have shown promising results in western and central Australia, however the safety of these new baits for non‐target species in eastern Australia, where many native animals are more sensitive to 1080 than their western conspecifics, has not been assessed. We investigated the uptake by non‐target animals of 499 toxic Eradicat® baits across five different eastern Australian environs, and the uptake of non‐toxic Eradicat® and Hisstory® baits at an additional two sites. Using field‐based observations of species eating or removing baits, we determined that 13 non‐target species (eight mammals, four birds, one reptile) were at high risk of individual mortality, with individuals of 11 of those 13 species (seven mammals, four birds) observed consuming enough toxic Eradicat® in a single visit to ingest a lethal dose of 1080. Feral cats (the target species) consumed only 3.1% of monitored baits, which was only 52% of the 31 baits they encountered. We recommend undertaking targeted population monitoring of species identified at high risk of individual mortality, to determine whether Eradicat® baits present a population‐level risk to these species. Our findings suggest that the small‐sized Eradicat® baits present a greater risk to non‐target species in eastern Australia than the larger traditional 1080‐based meat baits used for the control of wild dogs and foxes. Our study highlights the importance of performing risk assessments for different bait types, even when the same toxin is used, and of performing site‐specific non‐target risk assessments of new baits such as Eradicat® to assist developing guidelines for their safe and effective use in different environs. This article is protected by copyright. All rights reserved.
... Longer-term monitoring of the northern quoll populations at The findings from the field trial were similar to those from bait-uptake studies on free-ranging quolls elsewhere in Australia that demonstrated negligible impacts on this species group (King 1989;Körtner et al. 2003;Morris et al. 2003;Cremasco 2005;Körtner and Watson 2005;Claridge et al. 2006;Algar et al. 2017). For example, spotted-tailed quolls under free-ranging conditions showed that some individuals tested positive to the rhodamine B biomarker following aerial deployment of standard meat baits for wild dogs; however, the majority survived (Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007). Meat baits have been shown to be palatable to northern quolls; on Groote Eylandt, for example, a high proportion of northern quolls ingested (non-toxic) meat baits during field trials, suggesting that the bait medium was sufficiently attractive to eat (Heiniger et al. 2018). ...
... Such a learned feeding behaviour may be associated with the ability to taste 1080, as has been reported in other marsupials (Morgan 1982;Sinclair and Bird 1984;Calver et al. 1989;O'Connor et al. 2005). Sublethal exposure to 1080 may contribute to (primarily) female northern quolls learning to avoid EradicatÒ baits, as has been reported for spotted-tailed quolls (Körtner 2007). Annual dog baiting occurs across the Pilbara, so historical exposure of northern quolls to meat baits at Yarraloola may have predisposed animals to avoid ingesting EradicatÒ baits, although we think this is unlikely; work by King (1989) suggested that northern quolls are not affected by aerially broadcast poisoned dog baits. ...
Abstract
Context
Feral cats (Felis catus) are known predators of northern quolls (Dasyurus hallucatus). Management to suppress feral cat densities often uses the poison sodium monofluoroacetate (compound 1080) in baits broadcast aerially. Eradicat® baits have demonstrated efficacy at reducing feral cat densities in some environments. However, these are not registered for use in northern Australia as their risk to non-target northern quolls remains unknown.
Aims
We investigated the risks of aerially deployed feral cat Eradicat® baits containing 4.5 mg of the poison 1080 on the survival of free-ranging northern quolls.
Methods
The study was conducted over a 20,000-ha area in the Pilbara bioregion in Western Australia. Twenty-one wild northern quolls from a baited area and 20 quolls from a nearby reference area were fitted with radio-collars, and their survivorship compared following the aerial deployment of over 9,700 feral cat baits. Survivorship of quolls was assessed before and after the baiting campaign.
Key results
Five radio-collared quolls died at the baited area: four mortalities were due to feral cat predation, and the cause of one death was uncertain. At the reference area, seven radio-collared quolls were confirmed dead: three mortalities were due to feral cat predation, two from wild dog predation, and the cause of death of two could not be determined. Evidence for sub-lethal poison impacts on quolls - inferred by monitoring reproductive output – was lacking: average litter size was higher in quolls from the baited area compared to those in the unbaited area, and within range of litters reported elsewhere suggesting acute effects of 1080 (if ingested) on reproductive success were unlikely.
Conclusions
Radio-collared northern quolls survived the trial using Eradicat® baits, and females showed no acute effects of sublethal poisoning based on reproductive output. A lack of quoll deaths attributed to 1080 poisoning suggests the use of Eradicat® poses a low risk to northern quolls in the Pilbara. Importantly, the comparatively high level of mortalities associated with predation by feral cats – and to a lesser extent, canids – validates the threats of these introduced predators on quolls, suggesting their control in areas where quolls are present is likely to be beneficial for the recovery of this species.
Implications
Land managers aiming to conserve northern quolls in the Pilbara would see conservation benefits if they introduced an operational landscape-scale feral cat baiting program using Eradicat® baits, with appropriate monitoring.
... A concurrent aim of these programs is to minimise uptake by non-target animals, primarily to minimise bait removal (Claridge et al. 2006) rather than because of threats to non-target animals' welfare. Despite early concerns based on captive LD 50 trials of sodium fluoroacetate (Compound 1080, hereafter referred to as 1080; McIlroy 1981), field studies have consistently found no significant risk to south-eastern Australia's endemic spottedtailed quoll (Dasyurus maculatus maculatus) populations from poisoned baiting programs using the chemical (Körtner et al. 2003;Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007), which likely benefit their populations (Fleming and Ballard 2018). ...
... For managers to maximise the efficacy of lethal control efforts, baiting rates, overall bait quantity and transect routes must account for probable consumption of baits not only by target animals, but by other affected vertebrate pests, e.g. foxes and cats (Felis catus), and unaffected fauna too, such as ravens (McIlroy 1984), spotted-tailed quolls (Claridge and Mills 2007;Körtner 2007) and feral pigs (Millar et al. 2015). ...
ContextWild dogs, including dingoes and dingo cross-breeds, are vertebrate pests when they cause financial losses and emotional costs by harming livestock or pets, threaten human safety or endanger native fauna. Tools for lethal management of these animals currently include aerial baiting with poisoned baits. In New South Wales (NSW), Australia, aerial baiting was previously permitted at a rate of 40 baits km−1 but a maximum rate of 10 baits km−1 was subsequently prescribed by the Australian Pesticides and Veterinary Medicines Authority. The efficacy of these baiting rates has not been quantified in eastern Australia, undermining the value of the policy and rendering adaptive management efforts difficult, at best. AimTo quantify the mortality rate of wild dogs exposed to aerial baiting at historic and currently approved rates, i.e. 40 baits per kilometre and 10 baits per kilometre, respectively. Methods
Wild dog mortality rates were measured at sites in mesic north-eastern NSW, where aerial baiting was applied to control wild dogs and contrasted with sites and individuals where no baiting was undertaken. In total, 132 wild dogs were trapped and fitted with GPS-VHF telemetry collars before annual aerial baiting programs. Collars were used to locate animals after aerial baiting and to determine the fates of individuals. Key results90.6% of collared wild dogs exposed to aerial baiting at 40 baits km−1 died, whereas only 55.3% of those exposed to 10 baits km−1 died (Welsh’s t=4.478, P=0.004, v=6.95). All wild dogs that were not exposed to toxic baits survived during the same periods. Conclusion
Managers using aerial baiting to maximise wild dog mortality in mesic south-eastern Australia should use 40 baits km−1 rather than 10 baits km−1. ImplicationsWild dog population reduction for mitigation of livestock and faunal predation requires the application of efficacious control. The currently prescribed maximum aerial baiting rate of 10 baits km−1 is inadequate for controlling wild dog populations in mesic forest environments in NSW.
... It has since been established in several field experiments assessing actual baiting campaigns (toxic baits) that spotted-tailed quolls can and do consume at least parts of toxic fox and dog baits. Despite this behaviour, they rarely succumb to 1080 poisoning (Körtner et al. 2003;Cremasco 2005;Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007). Thus, 1080 poisoning may have very little influence on populations of spotted-tailed quolls where the extent of occupied habitat is large. ...
... Fortunately, the already highly threatened Tasmanian devil appears to be at less risk, given its large body size and resistance to 1080 (McIlroy 1981; Mooney et al. 2005;Hughes et al. 2011). If results from the mainland (Körtner et al. 2003;Cremasco 2005;Körtner and Watson 2005;Claridge and Mills 2007;Körtner 2007) can be extrapolated to Tasmania, then the risk to spotted-tailed quolls is probably also relatively low. Experimental verification measuring the direct effect of a 1080 baiting campaign would be still desirable. ...
... Foxes have caused devastation to both wildlife and agriculture on the Australian mainland (Saunders et al. 1995), costing over $200 million annually in biodiversity and economic losses (McLeod 2004). Whilst foxes are considered a major contributor to the demise of numerous mainland species (Kinnear et al. 1998;Burbidge and Manly 2002;Johnson 2006), Tasmania has escaped such devastation References: 1 Guiler (1985) 11 Guiler (1961) 21 Belcher (1998) 31 Glen et al. (2009) 2 Corbett (1995 12 Glen and Dickman (2005) 22 Saunders et al. (2006) 32 Soderquist andSerena (1993) 3 Jones et al. (2003) 13 Taylor (1986) 23 Burbidge and McKenzie (1989) 33 Abbott (2006) 4 Johnson andWroe (2003) 14 Rolls (1969) 24 Jones et al. (2004) 34 Oakwood (2000) 5 Green (1967 15 Maxwell et al. (1996) 25 King et al. (1989) 35 Burnett (1997) 6 Wood Jones (1923 16 Körtner (2007) 26 McIlroy (1981) 36 Oakwood andPritchard (1999) 7 Guiler (1982) 17 Belcher (2008) 27 Bennett (1990) 37 Mooney andRounsevell (2008) 8 Jones (2000) 18 Belcher and Darrant (2006) 28 Backhouse (1843) 38 Woinarski (2010) 9 Statham (2005 19 Jones and Rose (1996) 29 Morris et al. (2003) 39 Johnson (2006) 10 Hawkins et al. (2006 20 Burnett and Dickman (2008) 30 Orell and Morris (1994) 40 Paddle (2000) by remaining relatively fox-free until the late 1990's (Taylor 1986;Short and Smith 1994;Saunders et al. 2006). It has been claimed that foxes have had a disproportionately negative effect on mammals within a critical weight range (CWR) ...
... They could only conclude that eastern quolls are in low population densities in large, continuous areas of forest. They recommended that habitat associations be reviewed in areas where extensive clearance of native woodlands and grasslands has occurred, such as the Tasmanian (Körtner 2007). Active field-based testing should be combined with a spatial analysis correlating historic fox baiting locations with long-term spotlighting data. ...
... The period between ingestion and first detection of the marker in pulled whiskers ranges from <40 h to 2 months (Lindsey 1983;Fisher 1998;Jacob et al. 2002) and it has been successfully used as a biomarker in a suite of species (Table 1). It is considered the preferred method for detecting uptake of baits by mammalian species (Fisher 1998;Körtner et al. 2003;Claridge et al. 2006;Körtner 2007;Fenner et al. 2009). ...
... Fisher (1995) recommended that doses of RhB should be 50 mg kg -1 or more. The dose used by Fenner et al. (2009) (50 mg of RhB, mixed with the 1080 solution and injected into baits) met this recommendation and was comparable to amounts used in studies where the marker had been detected (Table 1) (Fairbridge et al. 2003;Körtner and Watson 2005;Claridge et al. 2006;Claridge and Mills 2007;Körtner 2007). Körtner et al. (2003) also used 50 mg of RhB in Foxoff ® (Animal Control Technologies, Melbourne) baits to assess RhB presence in whiskers of spotted-tailed quolls (Dasyurus maculatus) 3-4 weeks after baiting with toxic baits. ...
Context: The CURIOSITY® bait is the name coined for a variation of the existing sausage-style cat bait, ERADICAT®. The latter is used under experimental permit in Western Australia for research associated with cat control. The CURIOSITY bait differs from ERADICAT by providing a pH-buffered (less acidic) medium and has been proposed to reduce the risk to non-target species by encapsulating a toxin in a pellet. We trialled a prototype pellet proposed for encapsulation of 1080 and/or alternative toxins, with delivery proposed through the CURIOSITY bait.
Aim: Our aim was to determine whether the pellet was consumed by non-target native species from south-west of Western Australia.
Methods: Trials involved use of a non-toxic biomarker, Rhodamine B, encapsulated within the pellet and inserted into the CURIOSITY® bait. Uptake of the encapsulated biomarker was assessed in captive trials for the target species, the feral cat (Felis catus) and two non-target species of varanid lizard, Rosenberg’s goanna (Varanus rosenbergi) and Gould’s goanna (V. gouldii) and the non-target mammal species chuditch (Dasyurus geoffroii) and southern brown bandicoot (Isoodon obesulus). Uptake of the encapsulated biomarker was also assessed in field trials for a range of native species.
Key results: Captive trials demonstrated feral cats will consume the CURIOSITY bait and pellet. However, results from captive and field trials indicated several non-target species also consumed the bait and pellet. We also found the pellet itself was not sufficiently robust for use in a bait. As with previously reported studies, we found Rhodamine B to be an effective biomarker for use in cats. We also developed a technique whereby Rhodamine B can be used as a biomarker in reptiles. However, its use as a biomarker in other mammalian species was confounded by what appeared to be background, or pre-existing, levels of fluorescence, or banding, in their whiskers.
Conclusion: The prototype pellet is unsuitable in its current form for use with the CURIOSITY bait. We caution that the CURIOSITY bait has non-target issues in south-west of Western Australia and any proposed variations to this bait, or the ERADICAT® bait, need to be rigorously assessed for their potential risk to non-target species and assessed for the level of uptake by cats, irrespective of their suitability/unsuitability as a medium for delivery of an encapsulated toxin. We believe the threat to biodiversity-conservation values from unmitigated feral-cat predation of native fauna poses a significant and real threat and we recommend urgent investment of resources to address the issue of cat predation in a coordinated and collaborative manner within Australia and New Zealand.
... Alternatively, the absence of any individuals marked with RhB could suggest that, like the marsupial fat-tailed dunnart (Sminthopsis crassicaudata) and some other species (Morgan 1982; Sinclair and Bird 1984; Morgan et al. 1996; O'Connor et al. 2005), brown antechinus and bush rats might detect 1080 and avoid or at least decrease bait consumption to the extent of preventing poisoning and RhB marking. In conclusion, our data and several other studies conducted during the actual baiting campaigns to control canids suggest relatively low mortality rates of the native non-target species assessed and often a negligible impact on population levels (McIlroy 1982b; King 1989; Claridge and Mills 2007; Körtner 2007). They also highlight that laboratory (e.g. ...
... McIlroy 1981 McIlroy , 1982a) and simulation trials (e.g. McIlroy 1982b; Murray and Poore 2004) are not sufficient for predicting the impact of 1080-baiting campaigns on populations (King 1989; Claridge and Mills 2007; Körtner 2007). Therefore, determination of theoretical risk should be regarded only as a first step in assessing the actual risk faced by non-target species (King 1989; Körtner et al. 2003 ...
More than most other animal control techniques, toxic baiting is fraught with the potential impact on non-target species. In the present study, we investigated the effect of aerial baiting with 1080 to control wild dogs in north-eastern New South Wales (NSW), Australia, on populations of southern bush rats (Rattus fuscipes assimilis) and brown antechinus (Antechinus stuartii), using a controlled experiment. Six populations, three each within widely spaced baited and unbaited trapping grids, were monitored before and after bait laying. To develop capture–mark–recapture indices, separate 4-day trapping surveys were undertaken twice before and twice after meat baits (250 g containing 6 mg sodium fluoroacetate, 1080) were delivered from a helicopter at 40 baits per kilometre. To assess non-fatal bait consumption, all baits contained rhodamine B (RhB), which gets incorporated into the vibrissae of animals that have ingested this marker. Neither mammal population decreased in size after baiting, nor was there any increase in population turnover rates or changes in the movement patterns of either species. Furthermore, no trapped animal tested positive for RhB, suggesting that these small mammals rarely consume meat baits, and that, at the population level, the impact of baiting on them was likely negligible. It is therefore unlikely that the current practise of aerial baiting in NSW, although effective in reducing dog activity, threatens populations of these two common species and perhaps small mammals in general.
... Evidence from previous studies confirms that northern D. hallucatus (Oakwood 2000) and spotted-tailed (Körtner et al. 2004;Körtner & Watson 2005;Körtner 2007) quolls are frequently killed by other predators such as feral cats, foxes and wild dogs. Similarly, wild dogs in and around our study area consumed spotted-tailed quoll and cat (R. Harden & J. Robertshaw, unpublished data). ...
... This may indicate intraguild predation by dogs or that these animals were scavenged. Quolls killed by larger predators may not always be eaten (Körtner & Watson 2005;Körtner 2007). Therefore, although such interspecific killing is known to occur, its incidence may be underestimated by dietary studies. ...
The significance of top‐down regulation by carnivores is receiving increasing global recognition. As a consequence, key objectives in many programmes that seek to maintain ecosystem function now include conserving carnivores and understanding their interactions. This study examined overlap in resource use (space and diet) of introduced eutherian carnivores and an endangered marsupial carnivore, the spotted‐tailed quoll Dasyurus maculatus , in eastern Australia. We also investigated mechanisms of niche partitioning and evidence for interspecific aggression.
Dietary overlap between quolls, red foxes Vulpes vulpes and wild dogs Canis lupus ssp. was assessed by analysis of scats. Trapping, radio‐tracking and direct observations were used to quantify spatial overlap between quolls, foxes, wild dogs and feral cats Felis catus .
Dietary overlap among the carnivores was extensive. Medium‐sized mammals were the most important prey for all three predators, indicating potential for exploitative interactions. However, hunting of different size classes of secondary prey and consumption by quolls of more arboreal prey than their counterparts may assist coexistence. Remains of quoll were found in two dog scats, and cat hair in another, possibly indicating intraguild predation.
We observed extensive spatial overlap between quolls and eutherian carnivores. However, we inferred from dietary data that quolls foraged primarily in forested habitat, while canids foraged mainly in cleared habitat.
Synthesis and applications. Our results indicate strong potential for competition between spotted‐tailed quolls and eutherian carnivores, and thus a situation where control of introduced predators may be desirable, not only for the conservation of prey species but also for the protection of native carnivores. Concern over potential non‐target mortality of quolls has hindered efforts to control foxes in eastern Australia using poison baits. We contend that, rather than harming quoll populations, baiting for foxes should aid the conservation of quolls and should be implemented in areas of sympatry where fox numbers are high.
... Such observations led to concern that baiting may be detrimental to populations of D. maculatus. However, more rigorous field trials have since suggested that, for a number of reasons, this theoretical risk is not realized in the field (Körtner, 2007). ...
... Conclusions about the susceptibility of non-target animals based solely on bait removal should be treated with caution, because they do not take into account the fate of bait after it is removed (Körtner, 2007). An excellent example of this discrepancy between uptake and consumption is presented by Körtner et al. (2003) where 19 from 20 fox baits removed by spotted-tailed quolls were found uneaten a short distance from the bait station. ...
1. Mammalian predators are controlled by poison baiting in many parts of the world, often to alleviate their impacts on agriculture or the environment. Although predator control can have substantial benefits, the poisons used may also be potentially harmful to other wildlife.
2. Impacts on non-target species must be minimized, but can be difficult to predict or quantify. Species and individuals vary in their sensitivity to toxins and their propensity to consume poison baits, while populations vary in their resilience. Wildlife populations can accrue benefits from predator control, which outweigh the occasional deaths of non-target animals. We review recent advances in Australia, providing a framework for assessing non-target effects of poisoning operations and for developing techniques to minimize such effects. We also emphasize that weak or circumstantial evidence of non-target effects can be misleading.
3. Weak evidence that poison baiting presents a potential risk to non-target species comes from measuring the sensitivity of species to the toxin in the laboratory. More convincing evidence may be obtained by quantifying susceptibility in the field. This requires detailed information on the propensity of animals to locate and consume poison baits, as well as the likelihood of mortality if baits are consumed. Still stronger evidence may be obtained if predator baiting causes non-target mortality in the field (with toxin detected by post-mortem examination). Conclusive proof of a negative impact on populations of non-target species can be obtained only if any observed non-target mortality is followed by sustained reductions in population density.
4. Such proof is difficult to obtain and the possibility of a population-level impact cannot be reliably confirmed or dismissed without rigorous trials. In the absence of conclusive evidence, wildlife managers should adopt a precautionary approach which seeks to minimize potential risk to non-target individuals, while clarifying population-level effects through continued research.
... Calver et al. (1989) identified that in the laboratory, northern quolls were at risk from accidental poisoning from crackle baits containing 6 mg of 1080 for dingo control. However, there is an extensive literature demonstrating that theoretical risk derived from the above mentioned approaches rarely translates to actual risk faced by free-ranging native carnivores and other non-target species under field situations (King 1989;Körtner et al. 2003;Körtner and Watson 2006;Claridge and Mills 2007;Körtner 2007). Hence, these discrepancies between estimated bait toxicity and actual poisoning of quolls require resolution under field conditions (Jones et al. 2014). ...
... Because the baits were placed in open areas to allow good visibility for camera surveillance, it was possible that individuals moved the bait to a more protected point before consuming it. Conclusions about the susceptibility of non-target animals solely on the basis of bait removal should be treated with caution, because they do not take into account the fate of bait after it is removed (Körtner 2007). The camera trials alone did not resolve whether or not phascogales consume Eradicat Ò baits. ...
ContextFeral cats have benefitted from effective control of foxes in south-western Australia and, consequently, their impact on some threatened mammal species has increased. Control of feral cats in the region can be enhanced by use of the Eradicat® cat bait, but its impact on non-target animal populations requires investigation before widespread use. AimsThe aim of the present study was to determine through field trials whether consumption of Eradicat® baits by resident red-tailed phascogales, following a broadscale baiting operation to control feral cats, was sufficiently frequent to cause significant rates of mortality in wild populations of phascogales. Methods
Nine radio-tagged red-tailed phascogales were monitored through an Eradicat® baiting event to determine their survival. Removal and consumption of toxic and non-toxic rhodamine B-labelled baits by a range of species were monitored with camera traps and by subsequent trapping of red-tailed phascogales and other mammals to sample whiskers for evidence of rhodamine uptake. Key resultsAlthough some phascogales showed interest in baits and sometimes moved them from the deposition site, all radio-tagged phascogales survived for at least 1 week after baiting, by which time very few or no baits remained. Examination of whiskers sampled from individuals exposed to rhodamine-labelled baits showed that consumption of non-toxic Eradicat® baits by phascogales was negligible; only one phascogale of 62 sampled showed any rhodamine banding. Conclusions
The present study provided no evidence that red-tailed phascogales in the study region are at risk from an Eradicat® baiting episode in autumn. ImplicationsThe risk to red-tailed phascogale populations through the use of Eradicat® baiting to control cats in their habitat in the Great Southern region of Western Australia is likely to be low. Further research to elucidate any impact of repeated baiting on populations of this species at several locations is recommended.
... Flinders Ranges National Park; Robert Brandle, personal communication to GJ, 2018). Other species of quolls have also shown no negative response to fox, dog and cat baiting in the field (Belcher 1998, Kortner et al. 2003, Claridge and Mills 2007, Körtner 2007. Although limited, their resistance to 1080 is sufficient to protect western quolls from baits currently used to control foxes and cats. ...
... Previous studies have examined the implications of using fox baits in the presence of native carnivores including Quolls (King et al. 1989, Glen and Dickman 2003b, Körtner et al. 2003, Körtner 2007 and Brush-tailed phascogale (Phascogale tapoatafa Meyer), (Fairbridge et al. 2003, Marlow et al. 2015. One study revealed that native species including phascogale were able to consume buried 1080 baits during a fox control program (Fairbridge et al. 2003). ...
The use of fox 1080 (sodium fluroacetate) baits is an effective tool for controlling fox numbers in conservation areas. However, several native species are also highly susceptible to the poison. Previous studies have shown that Brush-tailed phascogale (Phascogale tapoatafa Meyer), were able to consume 1080 baits laid for foxes. Studies have not demonstrated if phascogale access baits directly from fox bait stations or via a secondary source. This is important as identifying where in the process phascogale access baits can allow land managers to develop key strategies to avoid off-target poisoning. Remote cameras were used to monitor a simulated fox 1080 baiting program. Two sites with active populations of Brush-tailed phascogale were chosen for the program. Free-feed stations were installed and monitored using infra-red motion detection cameras. The European red fox was the only species found to consume baits and there were no phascogale recorded at any bait stations. This research suggests that, if replicated under similar conditions, phascogale are unlikely to access poison for foxes directly from buried baits. Further research and additional free-feed experiments are needed to determine if other variables such as time of year, length of program and different baits could alter these findings.
... Included in the list are two species (Tiger Quoll and Long-nosed Potoroo) that are listed as Vulnerable in the Environment Protection and Biodiversity Conservation Act 1999. In contrast to this, Körtner and Watson (2005), Claridge and Mills (2007) and Körtner (2007) have reported that wild quolls rarely, if ever, die during 1080 aerial baiting campaigns, and that the practice is likely to benefit quolls due to the reduced competition from wild dogs, foxes and cats (Körtner and Watson 2005). ...
Felis catus, the domestic cat, occurs throughout the Australian mainland as well as on more than 40 islands off the Australian coast. Cats exploit diverse habitats, including deserts, forests, woodlands, grasslands, towns and cities, and occur from sea level to altitudes above 2000 m. The classification of cats as domestic, stray or feral (Moodie 1995) reflects the varied ecology of cats and their dichotomous status in Australia — as both a valued pet species and an introduced feral predator.
Impacts
Feral cats are carnivorous hunters that depredate animals up to 2 kg, but more often take prey under 200 g. The feral cat is linked to the early continental extinctions of up to seven species of mammals. They are also linked to island and regional extinctions of native mammals and birds and have caused the failure of reintroduction attempts aimed at re-establishing threatened species. Today, 35 vulnerable and endangered bird species, 36 mammal species, seven reptile species and three amphibian species are thought to be adversely affected by feral cats. Other species are potentially affected by infectious diseases transmitted by cats. The true environmental and economic impact of feral cats has not been calculated.
Legislation
In most Australian states and territories, legislation has been introduced to restrict the reproductive and predation potential of owned domestic cats. Many local government areas have introduced cat-specific legislation, with restrictions including the banning of cats as pets in some communities, compulsory neutering, individual identification, and containment of pet cats. Predation by feral cats was listed as a Key Threatening Process under the Federal Endangered Species Protection Act 1992 (now incorporated in the Environment Protection and Biodiversity Conservation Act 1999). A Threat Abatement Plan for Predation by Feral Cats was produced in 1999 and amended in 2008 to promote the recovery of vulnerable and endangered native species and threatened ecological communities (Environment Australia 1999 and DEWHA 2008).
Estimating abundance
The three most common techniques for estimating cat abundance in Australia are spotlighting, counting tracks, and bait uptake estimates. The accuracy of spotlighting is dependent upon the density of vegetative cover and cat behaviour; the accuracy of track counts depends upon where track pads are set and the competence of the operative in recognising tracks; and most bait uptake studies provide data on cat activity rather than relative abundance or densities. All three techniques are best suited to open, dry habitats with low vegetative cover. In wetter, more closed and productive habitats with high vegetative cover, techniques such as remote photography and the analysis of DNA extracted from scats or hairs provide alternatives for estimating abundance or density. Such estimates are a necessary prerequisite for the implementation of control or eradication programs to avoid over- or under-commitment of labour, time and money, and are also necessary to measure the efficacy of management programs.
Techniques for control or eradication
A nationally co-ordinated program of feral cat control across Australia is not feasible, as it is with other introduced species, and control efforts are best targeted at protecting threatened species or habitats. All successful cat eradication programs in Australia have been conducted on islands or within areas bounded by predator-proof fencing, and most have required the use of more than one control method. Successful techniques for the control or eradication of cats on islands have proved largely impractical on the mainland. Hunting, trapping and shooting are time and labour intensive and not economically viable over large areas. Trap-neuter-return is unsuccessful in open populations and not practical over large areas. The introduction of disease (e.g. panleucopaenia) is restricted by the probable impact on owned domestic cats and the low transmission rate amongst widely dispersed feral cats. Toxins presently registered for cat baiting may have unacceptable environmental impacts on many habitats. Research into more felid-specific toxins, cat attracting baits and lures and cat-specific toxin delivery systems may lead to the adoption of poisoning as the most widely used technique for the control or eradication of feral cats.
Management at the regional and local level
Management of feral cats requires reliable data on the density or relative abundance of cats in targeted areas, and analysis of the cost effectiveness and efficacy of the various control measures that may be implemented. At the regional and local level, eradication of cat colonies and the management of resource-rich artificial habitats to discourage colonisation by cats should be an adjunct to any feral cat control program. Implementation of companion animal legislation that requires firmer controls on the owned, domestic cat population is also an important consideration for the longer-term reduction of the feral cat population in Australia.
Factors limiting effective management
Although adequate legislation is in place in some jurisdictions, the problems associated with cat control programs in Australia include: the time, cost and social impacts associated with enforcing companion animal legislation; the acceptance in some states of cats as pest control agents; variable cat densities between habitats; relatively low bait acceptance by feral cats; a lack of programs aimed specifically at stray cat colonies exploiting highly modified habitats; little data on the impact of cat removal on populations of introduced rodents and rabbits; and few accurate estimates of the density or relative abundance of feral cats. Research is needed to define the most successful methods for gaining public acceptance of the importance of maintaining effective companion animal legislation; estimating densities of cats in various habitats; the cost effectiveness of control techniques including broadscale baiting; assessing the impact of the removal of colony-forming cats in resource-rich artificial habitats on the broader feral cat population; and assessing the impact of cat removal on both native and introduced small mammal populations and the further indirect effects of removal on other components of the biota.
... A number of other Australian studies have recorded direct evidence of intraguild predation or killing among mammalian carnivores. Radio-tracking has shown that predators such as foxes, dogs and cats can account for a substantial portion of observed mortalities in quolls (Dasyurus spp.) (Oakwood 2000;Morris et al. 2003;Körtner et al. 2004;Körtner and Watson 2005;Körtner 2007). In some cases the victims are partially consumed; in others they are left uneaten (Oakwood 2000). ...
Researchers often specialise on mammals, birds or reptiles, but terrestrial carnivore assemblages include predators from each of these taxonomic classes. Many of these animals use similar resources, and this can lead to a complex web of direct and indirect interactions. Factors that affect any one predator can have flow-on effects for other species. Whereas scientists and wildlife managers tend to focus on taxonomic groups, I argue that we need a broader approach. In this chapter, I describe common interactions among carnivores including exploitation and interference competition, intraguild killing or predation, and facilitation. Next, I present a meta-analysis of Australian carnivore research. Studies of predator interactions in Australia mostly consider only one taxonomic class, and are biased towards mammals. I then describe evidence of ecological interactions within and between taxonomic classes, identify gaps in current knowledge, and recommend priorities for further research. Future studies on predator interactions should consider mammalian, reptilian and avian predators, as well as flow-on effects for species at lower trophic levels.
... Such a simplistic view of susceptibility based on species' sensitivity to 1080 is, however, likely to overstate the non-target risk; conclusive proof can be obtained only through experimental ecological studies (Glen et al. 2007b). Despite the fact that some non-target individuals may succumb during baiting operations, no studies published to date, including those conducted on highly susceptible species, such as the spotted-tailed quoll Dasyurus maculatus, have found significant population-level reductions caused by 1080 baiting (King 1989, McIlroy 1999, Körtner et al. 2003, Körtner & Watson 2005, Morris et al. 2005, Claridge & Mills 2007, Körtner 2007. While any non-target deaths are regrettable, it is generally considered that some level of mortality among non-target populations is acceptable if this is outweighed by the benefits of pest control (see Choquenot & Ruscoe 1999 for discussion). ...
ABSTRACT • The successful introduction of the red fox Vulpes vulpes into Australia in the 1870s has had dramatic and deleterious impacts on both native fauna and agricultural production. Historical accounts detail how the arrival of foxes in many areas coincided with the local demise of native fauna. Recent analyses suggest that native fauna can be successfully reintroduced to their former ranges only if foxes have been controlled, and several replicated removal experiments have confirmed that foxes are the major agents of extirpation of native fauna. Predation is the primary cause of losses, but competition and transmission of disease may be important for some species. • In agricultural landscapes, fox predation on lambs can cause losses of 1–30%; variation is due to flock size, health and management, as well as differences in the timing and duration of lambing and the density of foxes. • Fox control measures include trapping, shooting, den fumigation and exclusion fencing; baiting using the toxin 1080 is the most commonly employed method. Depending on the baiting strategy, habitat and area covered, baiting can reduce fox activity by 50–97%. We review patterns of baiting in a large sheep-grazing region in central New South Wales, and propose guidelines to increase landholder awareness of baiting strategies, to concentrate and coordinate bait use, and to maximize the cost-effectiveness of baiting programs. • The variable reduction in fox density within the baited area, together with the ability of the fox to recolonize rapidly, suggest that current baiting practices in eastern Australia are often ineffective, and that reforms are required. These might include increasing landholder awareness and involvement in group control programs, and the use of more efficient broadscale techniques, such as aerial baiting.
... Both these subspecies are threatened, but, given research findings from north eastern NSW (e.g. [177,178]), it is unlikely that wild dog control is a threatening process for them [171]. Perhaps coincidentally, recent searches for south east Queensland research sites suitable to assess the effects on quoll populations of ground baiting for dogs with 1080, failed to find quoll populations except where dogs and foxes had been controlled (P. ...
... There are numerous examples of dogs killing other carnivores, both with and without consumption. For example, in Australia, dingoes have been recorded killing but not eating spotted-tailed quolls ( Dasyurus maculatus ) ( Körtner, 2007 ;Körtner and Watson, 2006 ), red foxes, and feral cats ( Moseby et al., 2012 ), but more generally they appear to eat or even cache their victims. Other than quolls, large varanids and snakes have been recorded in the diet of dingoes in several studies (e.g., Glen et al., 2011 ;Pascoe et al., 2012 ). ...
This chapter examines the interaction of dogs with other predators. It studies the competitive dynamic existing between dogs and other carnivores. It also assesses the implications of these reactions to the conservation of native carnivore species.
... Previous studies on quolls in northern New South Wales have focussed primarily on the potential impacts of poison baiting for wild canids (Körtner et al. 2003;Körtner and Watson 2005;Körtner 2006Körtner , 2007, although useful demographic data were obtained in conjunction with these experiments (Körtner et al. 2004). Wild populations of D. maculatus have also been studied in southern New South Wales and Victoria (Belcher 2003;Claridge et al. 2005;Dawson 2005), and in Tasmania Barmuta 1998, 2000). ...
The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore endemic to eastern Australia. A paucity of information on the dynamics of wild populations has hindered conservation of the species. The population dynamics of spotted-tailed quolls were investigated in an area of unusually high abundance in north-eastern New South Wales, where density is conservatively estimated at 0.3km-2. Sixty individual quolls were captured on 331 occasions over 22 months. Apparent survival, timing and rate of reproduction, and morphometric data were compared with those of quolls from other areas. Population models were employed to investigate patterns in the behaviour and apparent survival of quolls in the study area. The high abundance of D. maculatus identifies the study area as vital to the conservation of quolls on mainland Australia, and to the future study of the species.
... For instance, a succinct, high-impact seminar presentation to the executive of a government agency can initiate a whole research-management cycle with funding and stakeholder support being driven by executive-level expectations (e.g. Kortner 2007). In another example, support was achieved for a multimillion dollar study of the impact of fire on fauna in the Murray Mallee Region of NSW, Victoria and SA, when researchers from La Trobe and Deakin Universities convened a meeting in the region with staff from nine land management agencies and interested members of the general public (Stage 1). ...
Summary In conservation management, ensuring that the most appropriate research is conducted and results are actually put into practice is a complex and challenging process. While there are success stories, many hurdles can reduce the likelihood of appropriate research being initiated and its findings communicated and implemented. This article describes the ideal research–management cycle, summarizes the major factors that impede it and draws on the experiences of the authors to provide a series of examples of successful approaches to help keep the cycle going. We consider that the major impediments to a functioning research–management cycle relate to a lack of collaboration, poor communication, inappropriate funding and political timelines, change inertia and a lack of capacity. Although addressing structural difficulties such as matching funding timelines to those required for ecological research is a fundamental challenge, we can make incremental improvements to the way in which we operate that will improve the chances that research is both useful and used. The principles underpinning our success stories are (i) strategic development of capacity, (ii) increased breadth and depth of collaborations between researchers and managers and (iii) improved communications. Participants in the research–management cycle must seek to involve stakeholders through all project stages from project conception, to implementation, evaluation and knowledge updating. Finally, we should only see the first iteration of the research process as complete when new knowledge is applied operationally with monitoring and ongoing evaluation in place.
... Field studies assessing the potential impact of Foxoff baiting campaigns on spotted-tailed quolls on the mainland have generally found low individual mortality and no negative impact at the population level (Körtner et al. 2003, Körtner and Watson 2005, Glen et al. 2007, Körtner 2007. However, Belcher (2003) identified a correlation between Foxoff poisoning campaigns and declines in spotted-tailed quoll populations. ...
The recent introduction of red foxes (Vulpes vulpes) to Australia's island state of Tasmania represents a major threat to native fauna. In response, the Tasmanian government has begun a fox eradication program using Foxoff®, a bait containing the poison sodium monofluoroacetate (commonly known as 1080). The bait is potentially attractive to native Tasmanian carnivores as well as to foxes. Of particular concern is the endangered Tasmanian devil (Sarcophilus harrisii), which is already at risk from an emergent infectious disease, devil facial tumor disease (DFTD). In both a captive and a field study using non-toxic Foxoff bait, we assessed bait palatability and possible effects of demographics, hunger level, bait age, and bait burial method on the likelihood of bait uptake by Tasmanian devils. Captive devils showed varying interest in the bait, but wild devils appeared to find it uniformly palatable. In the captive study, males and younger, captive-born animals were more likely to excavate and remove bait. Subterranean burial at 15 cm was the most effective deterrent to bait excavation; effectiveness decreased at shallower depths and with surface-level bait buried beneath soil mounds. Our findings suggest that the current fox-baiting campaign may negatively impact individual devils. More extensive study is necessary to assess potential risk at the population level. © 2011 The Wildlife Society.
Context. In New Zealand, the aerial application of toxic baits containing sodium fluoroacetate (1080) can consistently achieve significant reductions in populations of multiple vertebrate pest species including brushtail possums (Trichosurus vulpecula), ship rats (Rattus rattus) and stoats (Mustela erminea). Reductions in house mouse (Mus musculus) populations by 1080 baiting appear less consistent, possibly due to low acceptance of 1080 bait by mice in field conditions. Aims. We tested the effect of pre-feeding and 1080 concentration on the acceptance of pellet food by mice. Methods. Wild-caught mice were individually housed and presented with a series of two-choice laboratory feeding tests, using estimates of the daily amount eaten to indicate relative acceptance of different types of pellet food. Key results. Pre-feeding mice on non-toxic food did not increase their subsequent acceptance of the same food containing 0.15% 1080. Mice showed low acceptance of food containing 0.08 and 0.15% 1080 (by weight), with similar mortality (25%). Acceptance of food containing 1.5% 1080 was also very low in comparison with non-toxic food, although mortality in mice was higher (∼66%). In comparison with other concentrations, mice ate comparatively more of food containing 0.001% 1080 with no mortality, although the non-toxic food was still significantly favoured. Presentation of a choice between non-toxic food and food containing 0.08, 0.15 or 1.5% 1080 to mice was followed by a significant decrease in average total daily food intake over the following 2 days. In surviving mice this 'drop feed' effect was followed by an increase in average daily intake of non-toxic food over the next 3 days until normal daily intake levels were again reached. Conclusions. We suggest that wild mice can rapidly identify food containing 1080 and subsequently will avoid it. Implications. This feeding response partly explains the variable success of 1080 baiting operations against wild mouse populations (M. musculus) in New Zealand.
Populations of red foxes (Vulpes vulpes) and wild dogs (Canis lupus dingo and hybrids with domestic dogs) are established within rural and urban habitats in Australia and highly target-specific oral delivery methods are sought. The comparative field performance of the M-44 ejector ('ejector') was compared with buried meat baits. At 16 independent field sites, equivalent numbers of baits and ejectors using the same unpoisoned bait as a lure were dosed with different systemic markers and deployed for a six-week period. A total of 74 wild dogs and 32 foxes were trapped and meat baits had marked 26% of wild dogs and 63% of foxes while ejectors marked 23% of wild dogs and 41% of foxes. No significant difference in the frequency of marking produced by either baits or ejectors was detected. The ancestry of the trapped wild dogs was investigated using known differences in allele frequencies between dingoes and domestic dogs and only 10.7% were classified as pure dingoes. Oral delivery with ejectors reduces the risk of non-target impact and eliminates translocation and caching of baits. More selective oral delivery assures a reduction in the number of non-target species exposed and implies a corresponding reduction in negative animal welfare impacts that occur incidental to the aims of some pest control programmes. Enhancing the selectivity of oral delivery to predators may address wildlife management and animal welfare needs more 2 conclusively than attempting to qualify and manage some often unclear risks associated with meat baits.
1080 (sodium fluoroacetate)-baiting programmes are an important and often the only option for reducing the impact of invasive vertebrate pests on biodiversity and agricultural production in Australia and New Zealand. These programmes are generally recognised as being target specific, and environmentally and user safe. Nevertheless, although 1080 has few recognised long-term side-effects, its potential to disrupt endocrine systems has been recently raised, and there is some conjecture regarding the humaneness of 1080 for certain target species. However, the assessment of the humaneness of any vertebrate pesticide must be commensurate with its mode of action, metabolism, target specificity, and operational use. This has not always occurred with 1080, particularly regarding these aspects, and its overall effects. The actual risk faced by non-target species during baiting operations is not accurately reflected simply by their sensitivity to 1080. 1080 is not endocrine-disrupting or carcinogenic, and because of the lag phase before signs of poisoning occur, the time from ingestion to death is not a reliable indicator of its humaneness. Moreover, functional receptors and neurological pathways are required to experience pain. However, as 1080 impairs neurological function, mainly through effects on acetylcholine and glutamate, and as this impairment includes some pain receptors, it is difficult to interpret the behaviour of affected animals, or to assess their ability to experience discomfort and pain. This has implications for assessing the merits of including ameliorative agents in 1080 baits aimed at further improving welfare outcomes. We also suggest that the assessment of the humaneness of any vertebrate pesticide should follow the ethical pest control approach, and on this basis, believe that the use of 1080 to reduce the detrimental impacts of invasive vertebrates is ethical, particularly with respect to the expectations of the wider community.
We determined the probable cause of possums becoming 'shy' towards 1080 bait, a growing problem in the control of this pest. Captive possums (n = 131) were offered sublethal baits (1 or 2·5 g) followed by lethal (6 g) baits two days later. Most possums became bait shy and the proportion becoming shy appeared to be related to the size of the initial sublethal dose. Most of a group of survivors retested after three months with toxic pellets were still shy. Shyness was not overcome by changing to a different mask (orange) or toxin (brodifacoum), but changing to both a different bait base (carrot) and mask (orange) resulted in most shy possums eating a lethal quantity of bait. Possums therefore appeared to leam to recognise the bait base as the cue for avoiding poisoning. More shy possums than naive possums rejected non-dyed, non-masked, non-toxic pellets confirming that shy possums recognised the bait base. Green dye appears to act as a secondary cue for avoiding pellets as a higher percentage of 'shy' possums than naive possums rejected dyed baits.
Short- and long-term trials were conducted to determine the rate of decline of 1080 (sodium fluoroacetate) in meat baits used for poisoning wild dogs. Baits were injected with 0.2 ml of standard 1080 solution (nominal dose of 6.00 mg of pure 1080 per bait) and placed in the field. In the long-term trial, 10 baits were collected at 7 intervals between 3 h and 226 days, and analysed for residual 1080 by liquid chromatography. The recoverable 1080 content declined greatly over the first 48 days, although at 226 days all 10 baits retained some 1080. By 42.4 days the mean residual level of 1080 in the baits was predicted to be less than the theoretical LD99 for wild dogs. At the time of distribution, baits contained less than the LD50 for an average-sized eastern quoll. The LD99 for domestic cattle-dogs was predicted to be still present in baits at 72.9 days. Loss of 1080 from these baits was not correlated with rainfall, temperature or humidity. In the short-term trial, 10 baits were collected at 11 intervals up to 200 h. The recoverable 1080 content decreased by 3.09 mg (61% of the injected dose) within the first hour after injection and declined to a low of 2.70 mg at hour 50. The level of recovered 1080 then rose to 73% of the injected dose at hour 150.
A monthly survey involving officers from eastern New South Wales Pastures Protection Boards was conducted over four years from 1982 to 1985. Information was collected on the number and type of livestock attacked within each board district, sightings of wild dogs, the number of wild dogs kiied, the method by which they were kiied and the locations at which the observations occurred. A total of 25,644 livestock animals were reported killed or wounded from four regions; the North-East Coastal Region, the North-East Tablelands Region, the Central-East Region and South-East Region. Sheep were the most commonly attacked domestic animals followed by cattle and goats. Regional differences were apparent in the type of livestock killed and seasonal patterns of predation were evident. We recommend that annual control programmes be brought forward from June/July to late April in order to precede predation peaks.
Radio-tracking of spotted-tailed quolls Dasyurus maculatus (Marsupialia: Dasyuridae) in the forested ranges of north-eastern New South Wales revealed that home ranges were extensive, with males occupying large, overlapping ranges [minimum convex polygon (MCP) up to 757 ha] and females occupying smaller, non-overlapping territories (MCP up to 175 ha). Quolls were partly arboreal, although most activity occurred on the ground or on fallen logs. Hollow logs were most frequently used as dens, but rock crevices, burrows, tree hollows and artificial structures were also used. Individual quolls were located in up to nine different dens and, with the exception of maternal dens, rarely sheltered in the same location on successive days. The large home ranges of the spotted-tailed quoll and the non-overlapping nature of female ranges necessitate very large areas of habitat to support viable populations. Fallen timber, used extensively for shelter and in travelling, may serve to enhance the quality of habitat for the species, and should be retained by forest and wildlife managers.
The hazard posed to northern quolls, Dasyurus hallucatus, during aerial baiting programs for the control of dingoes was studied in a pastoral area of Western Australia. The incidence of mortality and the movements of the animals were studied by means of radiotelemetry. Minimum activity areas ranged from 5 to 1109 ha, and the longest movement recorded was 3-5 km over 7 days. All animals could have encountered baits. Mating occurred shortly before baits were laid. The animals subsequently lost condition and body weights were low at the time of baiting. No quolls died in the 2 weeks following the baiting. This suggests that northern quolls and other, theoretically less susceptible, non-target species of mammals in the pastoral areas of Western Australia are not at risk from 1080 aerial baiting programs.
A number of cats in a captive population were fed 50 mg of Rhodamine B in non-toxic kangaroo meat baits. Samples of whiskers (mystacial vibrissae) taken 10 days later were examined for fluorescent marking. Examination of hairs for marking was carried out by means of a .single blind. trial, with the investigator having no prior knowledge of which of 36 cats had received the dye. All of the cats that had ingested baits containing the dye were marked. Examining hair samples under ambient light or under a hand-held ultraviolet (UV) light without magnification was not as reliable as examining hair samples under a fluorescence microscope. These results indicate that Rhodamine B acts as a reliable systemic marker of bait consumption in feral cats and has potential application in field studies to assess bait uptake by feral cats.
To assess the risk of secondary poisoning to dogs (Canis familiaris) which may scavenge carcasses of poisoned animals, possum carcasses were collected after a possum control operation using sodium monofluoroacetate (1080) paste baits, in Wairarapa, New Zealand, during 1994. The state of the decomposition of carcasses was assessed at intervals for up to 75 days and the 1080 concentrations of the stomach contents analysed. Carcasses collected from the field were found to contain concentrations of 1080 high enough to pose a serious hazard to dogs, even up to 75 days after the poisoning operation.
The tiger quoll is a large marsupial carnivore that occurs in forested habitat in south-eastern Australia. Three tiger quoll populations were trapped for up to six years and data on population parameters, including size, structure, sex ratio, adult : subadult ratio, weight, breeding characteristics, age and longevity were recorded for each population. Sex ratios (♂ : ♀) varied from 5 : 1 to 0 : 1. Population size and age structure reflected previous mortality events and social organisation traits, with all populations showing signs of instability due to disturbance events. Males did not reach full adult weight until three years of age and females until two years. Mean adult male weight was 2.81 kg ± 0.50 (s.d.) (range 2.0–4.2 kg) and mean adult female weight was 1.73 kg ± 0.22 (s.d.) (range 1.2–2.1 kg). Most females did not breed before two years of age and were recorded breeding up to four years of age. A proportion of females did not appear to breed in consecutive years. Matings were estimated to have occurred between late June and early August and births between mid-July and late August. Pouch litter size varied from 4 to 6 with a mean of 5.38 ± 0.65 (s.d.). The adult to juvenile ratio suggests that the mean number of young weaned per female is probably as low as one or two. Monitoring of four females found that the average number of young weaned was three with a range of 2–4. The maximum age recorded was five years. Population declines were found to correlate with 1080 poison baiting programmes, but not with selective logging.
Using a biomarker, we assessed the propensity of spotted-tailed quolls (Dasyurus maculatus) to encounter and consume non-toxic meat baits, ordinarily laced with the poison 1080 (sodium monofluoroacetate) and deployed for control of wild dogs (Canis lupus dingo, Canis familiaris and hybrids of the two) in southern Australia. In the first experiment, 60 unpoisoned meat baits injected with Rhodamine B were placed on the surface of the ground at 250-m intervals along two separate transects crossing an open woodland study area. One week after placement, a range of animals, including quolls, had removed all baits. Microscopic assay of whisker samples collected from live-captured quolls later revealed that 6 of 10 (60%) animals were positive for the biomarker, indicating that they had encountered and consumed baits. In the second experiment, conducted at the same site one year later, 150 similarly prepared meat baits were delivered aerially from a helicopter along the same transects, at a rate of one bait every 100 m. Eight of 17 quolls (47%) were found to have encountered and consumed at least one and up to five baits. Combined with previous studies, our results reaffirm that surface or aerial baiting operations for wild dogs may place local quoll populations at risk. However, further research is necessary to establish the relationship between this risk and actual mortality levels during such baiting operations since there are a number of factors that may influence the toxicity of baits for spotted-tailed quolls in a field situation as well as the danger those baits may pose.
In eastern Australia, the spotted-tailed quoll (Dasyurus maculatus) is the species thought to be most likely at risk from aerial baiting with compound 1080 to control wild dogs (Canis lupus familiaris and C. l. dingo). Although it is known that quolls occasionally die of 1080 poisoning, the broader impact on populations remains unresolved. We therefore assessed the impact of a regular aerial baiting campaign on a population of spotted-tailed quolls. Baiting with 1080 meat baits was conducted by the local Wild Dog Control Association and followed the same procedure as in previous years with the exception that the biomarker, rhodamine B, was added to the baits. Prior to the baiting, 36 quolls were trapped and fitted with mortality radio-collars; 31 of these collars were still functional at the time of baiting. Quolls were monitored from a helicopter and on the ground until retrapped 5-9 weeks after baiting. Transmitters were then removed and a sample of vibrissae was taken for rhodamine B analysis. Carcasses found were analysed for 1080. Predator numbers were assessed before and after baiting using track pads across trails. Among the initial 36 radio-collared quolls, nine mortalities were recorded during the course of the study (seven after baiting). Only one of the nine deaths could be directly attributed to 1080 poisoning. In addition, vibrissae from five of the 35 individuals sampled after baiting were marked with rhodamine B, indicating that these individuals had consumed bait, and survived. Consequently, mortality attributable to this particular aerial baiting campaign was low, apparently because few quolls ate bait and most of those that did survived. Track counts for predators indicated a significant decrease in dog and fox numbers after baiting. Cat activity remained unchanged and the number of quoll tracks increased.
The spotted-tailed quoll (Dasyurus maculatus) is a threatened marsupial that inhabits forests in eastern Australia. In many of these forests the species is sympatric with populations of wild dogs (Canis lupus dingo, Canis familiaris and hybrids of the two), which are subject to poison-baiting programs. Many of these programs involve dropping meat baits injected with 6 mg of 1080 from helicopters. To date, the effect of this method on populations of spotted-tailed quolls has not been quantified. We carried out a simulated aerial baiting program using meat baits injected with a non-toxic baitmarker, Rhodamine B, which is laid down in the vibrissae of mammals ingesting baits. Of the 16 spotted-tailed quolls subsequently captured, 10 had Rhodamine B in their vibrissae. The potential impact that this level of bait uptake might have on a population of quolls is discussed.
Between 2000 and 2002 two populations of the spotted-tailed quoll (Dasyurus maculatus) were studied on the New England Tablelands using trapping surveys and radio-tracking. Overall, 85 individuals were trapped, but only two individuals were trapped throughout the 26 months of the study. Trapping was male-biased (74%). Adult males (>1 year) were substantially larger than females. On average, males travelled longer distances than females, and the maximum distances recorded were 8.1 and 3.9 km for a male and female respectively. Home ranges of males overlapped substantially, whereas those of females appeared to be exclusive. Mortality rates and the turnover in the quoll populations appeared to be substantial and at the beginning of autumn the populations comprised ∼50% juveniles.
The level of fluoroacetate (1080) found in the carcasses of rats and rabbits poisoned with 1080 ranged from 1.9 to 14.4 μg g–1 (mean 5.3 μg g–1, n = 11) in rats and <0.02 to 0.78 μg g–1 (mean 0.353 μg g–1, n = 10) in rabbits. The concentration of fluoroacetate in the blood and liver of both species was generally higher than in the carcasses, and ranged from <0.02 to 33.6 μg g–1. Fifteen of 22 collared rabbits, and 3 freshly killed, uncollared rabbits were recovered during a routine baiting exercise with 1080 One-shot oats. Excluding the 4 collared rabbits taken by predators, only 14% of all carcasses (n = 14) were found in the open, with the remaining 86% of carcasses being well concealed in warrens or under thick scrub. The carcasses of both rabbits and rats showed considerable decay within 6 days of poisoning. Except for eutherian carnivores, which are highly sensitive to 1080, there is little potential risk of secondary poisoning of native wildlife as a result of the correct use of 1080 baits in pest-control programs.
Injection and mixing techniques for the preparation of fresh meat baits containing sodium monofluoroacetate
(1080) were evaluated. Both techniques produced baits containing variable quantities
of 1080. The injection of 1 ml of 6.0-mg ml-1 1080 and 0.5 ml of 13.6-mg ml-1 1080 solution
produced baits containing (mean ± SD) 2.9 ± 0.6 and 3.5 ± 0.5 mg of 1080 respectively; the ranges
were 1.9-4.1 and 2.1-4.4 mg respectively. Decreasing the injection volume while increasing the 1080
concentration did not increase the percentage of 1080 recovered from baits. Mixed baits prepared by
tumbling with 1 ml of 5.7-mg ml-1 1080 and 1 ml of 10-mg ml-1 1080 per bait contained 3.8 ± 1.9
and 5.3 ± 2.1 mg of 1080 respectively, with respective ranges of 1.2-11.3 and 1.2-13.2 mg per bait.
The injection method produced baits more uniform with respect to the amount of 1080 in the bait.
A significant fraction of the 1080 added in both methods of preparation was not found. Experiments
showed that this loss was due to biochemical reaction rather than physical loss.
Sminthopsis crassicaudata is a small dasyurid marsupial that may be exposed to 1080 poison during the
baiting of dingoes with fresh meat baits. A group of Sminthopsis were conditioned to feed freely on meat
in the laboratory, but when they were offered meat poisoned with 1080 their intake was significantly
reduced and they vomited. Some of them refused to eat meat altogether even when a choice of poisoned
and unpoisoned meat was provided. Fewer Sminthopsis died after eating poisoned meat than expected
from the LD*50 estimated by a standard technique of oral dosing with 1080 in water. Loss of appetite and
aversion to the taste and/or smell of meat containing 1080 are discussed as reasons for the low intake of
poisoned meat. Implications of these results are considered in the light of assessing risk to other
non-target species exposed to baits containing 1080.
Meat baits injected with '1080' poison (sodium monofluoroacetate) according to the method recommended by the Department of Agriculture, New South Wales, Australia, for preparing baits for poisoning compaigns against wild dogs (Canis f. familiaris) and dingoes (C. f. dingo), began to lose their toxicity from the moment of preparation onwards, particularly after different rainfall treatments and when inhabited by calliphorid larvae. The main or most likely reasons for the loss of fluoroacetate were consumption by maggots (mainly larvae of Calliphora augur and C. stygia plus some C. hilli and C. tibialis) and their subsequent disappearance from the baits, leaching by rainfall, defluorination of the fluoroacetate by micro-organisms, and leakage from the baits after injection and during their decomposition. During this study the baits remained toxic to dogs, despite different rainfall treatments, for over 32 days during winter when maggots were absent, and for 6-31 days during summer, when they were present. Under the same conditions the baits contained an LD50 for an average-sized tiger quoll (Dasyurus maculatus) for 4-15 days and 2-4 days, respectively.
A method is described for the determination of trace amounts of sodium monofluoroacetate (MFA-Na) in soil and biological samples. Soil samples were sonicated with distilled water in the presence of basic magnesium carbonate. Biological samples were extracted with distilled water by sonication and the extracts were coagulated by addition of equal volumes of alcohol and centrifuged. MFA-Na in each sample solution was adsorbed on Dowex 1-X8 anion-exchange resin and eluted with 2% (w/v) sodium chloride. The eluate was acidified with hydrochloric acid and treated with 2,4-dichloroaniline and N,N′-dicyclohexylcarbodiimide. The dichloroanilide derivative of MFA-Na was extracted with ethyl acetate and quantified by gas chromatography with electron-capture detection and gas chromatography—mass spectrometry. The detection limits were 0.0015 and 0.003 μg/g in 20 g of soil and 10 g of biological sample, respectively.
In Australia, baiting with 1080 (sodium fluoroacetate) is widely used to reduce predation of native wildlife by the red fox. However, such control programs may place some native carnivores at risk, particularly the spotted-tailed quoll in eastern Australia. We measured the mortality in a total of 57 quolls fitted with mortality radio-transmitters during four experimental fox baitings with Foxoff® 1080 baits containing Rhodamine B in north-east New South Wales. In all experiments quolls visited bait stations regularly and removed a total of 20 baits. All but one of these baits was found in the vicinity of the bait station, indicating that quolls did not ingest baits. This was confirmed by the absence of Rhodamine B in the vibrissae of all quolls retrapped after baiting. The only quoll that may have died from a bait had eaten a cached bait some six weeks after baiting concluded. Thus, baiting did not threaten any of the quoll populations sampled. Therefore it appears that most restrictions imposed to protect spotted-tailed quolls during fox baiting are unnecessary as long as this bait type is used.
Captive trials were undertaken to determine whether tiger quolls and eastern
quolls could detect baits that were either buried or covered with soil
following the methods employed in normal buried-poisoned-bait programmes. Both
tiger quolls and eastern quolls detected, dug up and consumed buried FOXOFF
baits. Consumption trials showed that tiger quolls were capable of consuming
2–3 FOXOFF baits in a single meal and more than three baits overnight.
Eastern quolls could consume up to 1.5 baits in a single meal.
Field trials were undertaken to investigate whether tiger quolls in the wild
could also detect and consume buried baits. Trials with both fresh meat and
FOXOFF baits were undertaken at a site near a tiger quoll latrine, using a
remote camera to record visits to the site and bait uptake. The results
confirmed that tiger quolls in the wild can detect and consume both fresh meat
and FOXOFF baits that have been buried or placed on the surface and covered
with soil to a depth of 5–8 cm.
The results indicate that the buried-bait technique is not specific for
introduced predators, and free- feeding may not preclude non-target species
from taking buried baits. Reliance on the identification of the species
visiting bait stations from tracks may also be unreliable as foxes dug up bait
stations searching for baits, even after the bait had been removed,
potentially obliterating other tracks.
Eutherian carnivores tested were more sensitive to 1080 poison than marsupial carnivores. Both groups of animals displayed similar symptoms but there was wide intra- and interspecific variation in the time to onset, the sequence of occurrence and duration of the symptoms. The risks that individual carnivores face from primary and secondary poisoning have been assessed. Theoretically, dingoes probably face the greatest risk amongst the species studied, followed by members of the smaller dasyurids and feral cats. Members of the larger dasyurids and long-nosed bandicoots probably face the least risk. Factors likely to influence the actual effect of 1080-poisoning campaigns on carnivore populations are dis- cussed.
A liquid chromatographic (LC) method is described for the determination of sodium fluoroacetate in meat baits and formulations. Baits were extracted with water, ultrafiltered, partitioned into butanone, back-partitioned into dilute base, and diluted with acetonitrile. Aqueous formulations of 1080 were diluted with acetonitrile. The solutions were esterified with p-bromophenacyl bromide, using crown ether catalysis, and chromatographed on a 10 micron reverse phase column. Ultraviolet absorbance was monitored at 260 nm. Samples spiked to contain 1 mg and 10 mg 1080/100 g meat gave recoveries of 84.0-103.4%.
Tiger quolls, Dasyurus maculatus, are the largest carnivorous marsupials still extant on the mainland of Australia, and occupy an important ecological niche as top predators and scavengers. Two allopatric subspecies are recognized, D.m. gracilis in north Queensland, and D.m. maculatus in the southeast of the mainland and Tasmania. D.m. gracilis is considered endangered while D.m. maculatus is listed as vulnerable to extinction; both subspecies are still in decline. Phylogeographical subdivision was examined to determine evolutionarily significant units (ESUs) and management units (MUs) among populations of tiger quolls to assist in the conservation of these taxa. Ninety-three tiger quolls from nine representative populations were sampled from throughout the species range. Six nuclear microsatellite loci and the mitochondrial DNA (mtDNA) control region (471 bp) were used to examine ESUs and MUs in this species. We demonstrated that Tasmanian tiger quolls are reciprocally monophyletic to those from the mainland using mtDNA analysis, but D.m. gracilis was not monophyletic with respect to mainland D.m. maculatus. Analysis of microsatellite loci also revealed significant differences between the Tasmanian and mainland tiger quolls, and between D.m. gracilis and mainland D.m. maculatus. These results indicate that Tasmanian and mainland tiger quolls form two distinct evolutionary units but that D.m. gracilis and mainland D.m. maculatus are different MUs within the same ESU. The two marker types used in this study revealed different male and female dispersal patterns and indicate that the most appropriate units for short-term management are local populations. A revised classification and management plan are needed for tiger quolls, particularly in relation to conservation of the Tasmanian and Queensland populations.