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Rodenticide and vertebrate pesticide registrations have declined worldwide over the last 30 years. New Zealand has not followed this trend, instead retaining essential toxins and traps, improving their use and exploring new mammal control tools. Looking to the immediate future, as well as continuing to improve the use of existing tools, there are opportunities for further advances in emerging technologies such as wireless technology for species recognition and aiding trapping programmes, self-resetting traps and toxin-delivery systems to be enhanced with advanced lures, and new toxins which increasingly combine ‘low-residue’ characteristics with selectivity and humaneness. More selective baiting and delivery systems will enable more targeted control of possums, mustelids and rodents. The use of new toxins with advantages in specific settings should be complemented by improvements in resetting trap technology, barrier approaches, and novel biocontrol and genetic concepts. Sodium fluoroacetate (1080...

Bennett's wallaby (Macropus rufogriseus rufogriseus) are an introduced pest requiring control in New Zealand. Historically, sodium fluoroacetate (1080) has been used, but there is political resistance to this method of control from specific interest groups. Previous trials with captive animals have shown that Feratox® cyanide pellets are efficacious for Bennett's wallaby and the aim of this study was to field test Feratox®. A 300-ha treatment block was pre-fed non-toxic bait for 2 weeks followed by the presentation of 200-mg Feratox® pellets. Rates of faecal pellet accumulation were markedly higher in the non-treatment block following control and the Guildford score of wallaby abundance reduced from 5 to 2 in the treatment block. In total, 110 dead wallabies were found less than 50 m from the baiting sites. These results suggest that Feratox® is an effective ground-based alternative to 1080 for Bennett's wallaby control.

The risks of vertebrate pesticides to non-target animals are determined by intrinsic susceptibility, the toxicokinetics of the compounds used, and the degree and frequency of exposure. Metabolism and persistence studies coupled with field surveys have provided us with an improved understanding of the toxicokinetics and non-target effects of different anticoagulants. This has enabled improved choice of tools for island versus mainland use in New Zealand, and has stimulated the development of low-residue tools. Brodifacoum is a potent second-generation rodenticide used worldwide for commensal rodent control, and has been widely used to eradicate rodents from islands. The risks associated with ‘one-off’ application of baits containing second-generation anticoagulants for rodent eradication on islands are considered to be outweighed by the potential benefits to their ecosystems. Possums are susceptible to bait containing brodifacoum, but not to first-generation anticoagulants, hence brodifacoum has b...

Non-toxic prefeeding is often used to increase the efficacy of aerial poisoning of possums (Trichosurus vulpecula) by increasing their willingness to accept toxic bait. An important question is whether that increased acceptance lasts more than a few days or weeks– if not, repeated prefeeding might be required if the poisoning was delayed by poor weather. We presented 48 captive possums with 100 g of non–toxic bait for 40 min on three or more occasions at a range of intervals (1–28 days), and measured bait consumption on each occasion. Bait consumption increased from a mean (±SE) of 23.3 ± 2.5 g on first encounter to 32.9 ± 2.4 g on the second encounter, but without further increase on the third encounter (32.7 ± 2.5 g). The amount of bait eaten increased (rather than decreased) as the time between exposures increased. When possums were subsequently offered toxic bait (sodium monofluoroacetate) at a range of intervals (10–50 days) after their last exposure to prefeed, there was no evidence that am...

Stoats (Mustela erminea) are an important predator of many forest bird species in New Zealand, and more effective methods for their control are being sought. Stoat control using Fenn traps has been shown to prevent predation on mohua (Mohoua ochrocephala), but this technique is labour‐intensive and costly to use for protection of large areas of habitat. We evaluated 1080 delivered in eggs as a poison for control of stoats. The lethal dose has been determined by captive and field trials, but attempts to implement a large‐scale control operation have given inconclusive results. To clarify the effectiveness of 1080 eggs as a control technique, we carried out further field trials with radio‐tagged stoats in the Makarora Valley. Twenty animals were monitored by radio tracking, and data loggers and video cameras recorded their visits to bait stations. The precise time an individual stoat ate a poison egg could be determined from data logger and video information, and its fate was followed. Sixteen of t...

Control of stoats (Mustela erminea) using sodium monofluoroacetate (1080) injected into hen eggs was investigated in pen and field trials. For captive stoats, the LD50 of 1080 in hen eggs was 0.49 mg/kg and the LD90 was 0.70 mg/kg. In a field efficacy trial using 1080‐poisoned hen eggs in bait stations, consumption of eggs was reduced by 91.9% in the poison area relative to the non‐poison area within 22 days. Video recordings showed stoats, a possum, and a kea approached bait stations, but only stoats entered and ate eggs. In subsequent live‐trapping, one stoat was caught in 91.5 trap nights (1.09/100TN) in the poison area and eight stoats in 101 trap nights (7.92/100TN) in the non‐poison area. Assuming stoat numbers in the two areas were similar before poison‐baiting (a reasonable assumption based on egg consumption rates), this represents an 86.2% reduction in the number of stoats in the poison area relative to the non‐poison area. Success should be even greater in management operations, becaus...

Poison-baiting trials were carried out in Canterbury, Nelson, and Westland in 1986/87 to 1989/90 to reduce wasp (predominantly Vespula vulgaris) populations. Compound 1080 was mixed with canned sardine in aspic jelly for bait. Bait stations were put out in areas of 1.5–3 ha, at a density of about 40/ha. Wasps were pre-fed with non-toxic bait for at least 3 days before poisoning.Poison-baits containing 0.001% and 0.01% 1080 had no significant effect on wasp traffic at nest entrances, 0.1% 1080 reduced wasp traffic by 17%, 0.5% 1080 by 78%, and 1% 1080 by 89%. Reduction in wasp numbers after poisoning with 0.5% or 1% 1080 was rapid, up to 100% within 6 h. The level of reduction declined beyond 100 m from bait stations. After poisoning, wasp traffic at nests within 100 m of bait stations remained low for the rest of the season, but partially recovered at nests more than 100 m from baits. Wasp numbers visiting bait stations containing non-toxic baits increased to about 30% of pre-poison levels 4 weeks...

The behaviour of honey bees feeding on sodium fluoroacetate-jam baits, which are used for opossum control, was investigated to determine the reasons for reported honey bee kills. Honey bees were shown to feed readily on 1080-jam baits when they were presented outside their hives. There were no debilitating effects for up to 2 h after feeding on the baits, which allowed them to make up to four foraging trips to the baits and recruit additional foragers.Black strap molasses was shown to have a repellent effect on honey bees when mixed with the jam baits. Foragers were able to detect differences in concentration of as little as 5%. Twenty percent molasses was found to repel inexperienced foragers strongly; however, they could be trained to accept higher concentrations. Two percent oxalic acid (a component of molasses) was found to repel honey bees when added to 2M sugar syrup or jam baits. Molasses-jam baits and jam baits appeared to be equally attractive to opossums when tested in the field.These re...