2002
Threat abatement project ID: 00016505
About the report
The NSW Threat Abatement Plan for Predation by the Red Fox (TAP) identifies foxes as a major threat to the survival of many native mammals. The plan recommends baiting with compound 1080 (sodium monofluoroacetate) because it appears to be the most effective fox control measure. However, the plan also recognises the risk for tiger quolls as a non-target species. Although the actual impact of 1080 fox baiting on tiger quoll populations has not been assessed, this assumed risk has resulted in restrictions on the use of 1080 which render fox baiting programs labour intensive and expensive and which may compromise the effectiveness of the fox control.
The aim of this project is to determine whether these precautions are necessary by measuring tiger quoll mortality during fox baiting programs using 1080. The project has been identified as a priority action (Obj. 2, action 5) of the TAP.
Three experiments were conducted in north-east NSW between June 2000 and December 2001. Overall 78 quolls were trapped and 56 of those were fitted with mortality radio-transmitters. Baiting procedure followed Best Practice Guidelines (TAP) except that there was no free-feeding and baits were only surface buried. These modifications aimed to increase the exposure of quolls to bait. 1080 baits (3 mg / bait; Foxoff®) incorporating the bait marker Rhodamine B were deployed for 10 days along existing trails. Baits were buried just below the surface of a pad of sand (bait station), which was used to identify prints of visiting animals. Bait stations and radio-collared quolls were monitored daily.
Only the study area for the first two experiments (Werrikimbe NP) harboured a significant number of foxes. Bait takes by foxes were recorded regularly in Werrikimbe NP during both experiments. However, a decrease of fox numbers, measured by counting fox tracks on tracking pads across trails, could be demonstrated only during the first experiment. Foxes were rare in the area used for the third experiment precluding an assessment of the effect of baiting on fox populations.
During the three experiments a total of 37 quoll visits to bait stations were recorded. On 13 occasions quolls excavated and removed the bait. However, in all but one of these cases we were able to retrieve the bait from the vicinity of the bait station (distance from bait station up to 30m). In these cases at most only small pieces had been bitten off the bait before it was discarded. The only bait take where we did not retrieve the bait occurred during the first experiment, before we had began to make a concerted effort to find baits removed from bait stations. The absence of the bait marker (Rhodamine B) in the vibrissae of all quolls trapped after the baiting (analysis for the last experiment is pending) was consistent with the observed bait rejection. Furthermore, none of the radio-collared quolls succumbed to the baiting.
In these three experiments, fox baiting clearly did not threaten the tiger quoll population. However, the primary reason for this was that quolls did not consume any bait, and thus the question of whether quolls can survive bait consumption was not resolved. It appears that quolls find Foxoff® baits unpalatable, either because of the 1080 or because of the bait matrix itself. Regardless of the reasons for bait rejection, deep burial of bait, the daily monitoring of bait stations and free-feeding prior to baiting appear to be unnecessary as long as this specific bait type is used.
See also