The propensity of spotted-tailed quolls (Dasyurus maculatus) to encounter and consume non-toxic meat baits in a simulated canid-control program

Abstract

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.

Aerial baiting with 1080 to control wild dogs does not affect the populations of two common small mammal species

“…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;Körtner and Watson 2005;Claridge et al 2006;Claridge and Mills 2007;Körtner 2007). Without monitoring the fate of individual animals and populations during the actual baiting campaigns, any risk assessments of baiting remain highly speculative and can lead to erroneous management decisions.…”

1080 aerial baiting for the control of wild dogs and its impact on spotted-tailed quoll (Dasyurus maculatus) populations in eastern Australia

“…It appears likely that none of the radio-collared quolls died of acute 1080 poisoning, but most quolls had eaten 1080 dog baits and survived bait consumption. Hence, under natural conditions quolls are probably less prone to fatal poisoning than laboratory-based toxicology studies (McIlroy 1981) and simulation trials using non-toxic baits laced with rhodamine B have suggested (Murray and Poore 2004;Claridge et al 2006).…”

“…Consequently, after a relatively short period baits will cease to be lethal to quolls (and other species, as illustrated by the rhodamine B-positive cats). Hence it is unlikely that bait-consumption figures derived from rhodamine B markings over relatively long periods during simulation trials could be extrapolated to mortality rates during toxic baiting campaigns (Claridge et al 2006). Second, the LD 50 s of 1080 (dose rate at which 50% of the studied population died) for quolls and other species were generally obtained by infusing a purified 1080 solution into test animals (McIlroy 1981).…”

“…This assessment is mainly based on the dietary habit of spotted-tailed quolls, which includes scavenging, and its high sensitivity to 1080 compared with other quoll species (McIlroy 1981;Belcher 1998, Jones et al 2003. That quolls readily consume meat baits, at least non-toxic ones, has been established in several simulated baiting trials conducted in southern New South Wales (NSW) (Belcher 2004;Murray and Poore 2004;Claridge et al 2006). There have also been some recorded quoll mortalities, which could be attributed to 1080 poisoning (Belcher 2003;Körtner and Watson 2005;Cremasco 2005).…”

“…Considering the marked difference to the predictions derived from simulation studies (Murray and Poore 2004;Claridge et al 2006), further field trials were clearly needed as a premature increase in aerial baiting to combat wild dog problems could be disastrous for spotted-tailed quoll populations, especially those naïve to baiting. The aim of the present trial was therefore not only to replicate previous trials, but also to inves-tigate whether quoll populations without a recent history of aerial baiting are more vulnerable.…”