Field trials of slow‐release synthetic lures for stoats (Mustela erminea) and ferrets (M. furo)

Abstract

Experimental field trials were used to compare the attractiveness to stoats (Mustela erminea) and ferrets (M. furo) of traps set with either a synthetic scent lure or with fresh food bait. One lure, containing 2‐n‐propylthietane, effectively attracted as many ferrets as did rabbit meat bait. Fewer stoats were caught with this lure than with egg bait. Made up in a slow‐release formulation in “plastic rope”, the lure remained attractive to ferrets for at least 2 weeks under sunny field conditions. Traps containing a second lure, 3‐n‐propyl‐l,2‐dithiolane, were less successful at catching both mustelid species than those containing fresh food baits. The scent lures were not attractive to non‐target species, but neither did they deter some species.     

Evaluation of iophenoxic acid and rhodamine B for marking feral ferrets (Mustela furo)

Abstract

The blood marker iophenoxic acid, and the fluorescent dye rhodamine B, were evaluated as means of assessing bait consumption in the ferret, Mustela furo. Iophenoxic acid was elevated above baseline concentrations for a minimum of 28 days after dosing, indicating that it is a suitable medium‐term marker. Rhodamine B marked ferrets for a maximum of 7 days, and would therefore have limited operational use with feral ferrets. Iophenoxic acid was used in a field trial to assess the effectiveness of a newly developed baiting strategy for control of wild ferrets. All 21 ferrets captured after field baiting with iophenoxic acid had elevated levels of serum iodine, indicating that the newly developed baiting strategy is highly effective for marking ferrets.     

Rodents and their predators in the eastern Bay of Islands

Abstract

Traps were set for rodents and mustelids on five islands (Motukiekie, Moturua, Okahu, Urupukapuka, and Waewaetorea) in the eastern Bay of Islands in March 1984. Kiore (Rattus exulans) were caught on Moturua Island and Norway rats (R. norvegicus) on all five islands, but no mustelids were caught or seen. Kiore on Moturua Island were very scarce compared with other northern offshore islands, perhaps because of competition from Norway rats and the presence of stoats and cats. Kiore were breeding and young matured in the season of their birth. Norway rats were scarce and found mainly near the shoreline on four of the islands. On Waewaetorea Island they were plentiful and widespread despite the possible presence of stoats. About a third of the mature females were visibly pregnant. Average litter size was 6.9 embryos, and 44% of the parous females had borne two or three litters. Females first ovulated at 180 ± 5 g weight and 356 ± 5 mm total length on average. Males first produced sperm at 189 ± 7 g weight and 364 ± 4 mm total length. Most rats matured before reaching a tooth-wear age index of 5.     

Ectoparasites of the Irish stoat

A sample of 196 Irish stoats Mustela ermineae hibernica Thomas & Barrett-Hamilton (Carnivora: Mustelidae) were examined and yielded 2580 arthropod ectoparasites, including 1819 larval mites Neotrombicula autumnalis (Shaw) from a single host. Other ectoparasites recovered included lice (99% Trichodectes ermineae (Hopkins], ticks (mostly Ixodes hexagonus Leach) and four species of fleas. The ticks and fleas were considered to have come mainly from nests of other hosts. The flea species did not reflect the status of their usual hosts in the diet of stoats, but did reflect the stoats' use of their usual hosts' habitat.     

Field experiments on the trapping of stoats (Mustela erminea)

Abstract

Steel Fenn traps spaced at 100 m, 200 m, 400 m, and 800 m intervals (total 88 traps) were set in the Eglinton and Hollyford valleys, Fiordland, New Zealand, for 14 days a month from November 1974 to March 1976. A total of 173 stoats were caught, mostly in the two summers. The number of stoats caught and the proportion of females did not change with trap spacing, but both were higher than in an earlier, informal trapping campaign in the same area (20 traps at 2.1 km average interval; 124 stoats caught). The capture rate on the experimental lines declined from 1.07 stoats per 100 trap-nights at the beginning of the average 14-day session to 0.42 at the end, a reduction of 60%. Immigration between trapping sessions probably occurred in all months, but was most marked in summer. The usefulness of the data for the formulation of management policies concerning stoats in the National Parks of New Zealand will be discussed, along with other relevant information, elsewhere.     

Amplification success rate of DNA from museum skin collections: a case study of stoats from 18 museums

There are large museum collections of mammalian skins and we wished to determine their usefulness for DNA‐based evolutionary and conservation studies. Methods derived from the ancient DNA approach were used to process samples from skins of the stoat (Mustela erminea) from 18 museums in 11 countries. Successful polymerase chain reaction (PCR) amplification was achieved in 56%, 46% and 40% of all samples for 0.65‐, 0.70‐ and 0.78‐kb PCR products of mitochondrial DNA, respectively. Some of the best‐preserved skin samples were those in tight‐fitting containers in a dry and cold environment. With care in their preservation, mammalian skin collections may be a good source of DNA.     

The biology of the stoat (Mustela erminea) in the National Parks of New Zealand VI. Infestation with Skrjabingylus nasicola

Abstract

The natural distribution of the parasite Skrjabingylus nasicola was surveyed in 1492 stoats from New Zealand’s National Parks. Infestation was rare in the young, so distribution was expressed as frequency of occurrence of skulls containing nematodes in samples of stoats more than 6 months old. Conservative estimates of incidence ranged from 0 to 37% in 27 local subsamples with at least 6 adults and subadults (mean 10%, n = 1005), sometimes varying substantially across short distances. Incidence was highest in beech forest and scrub/grassland habitats with annual rainfall less than 1600 mm. Subadult males (6–10 months old) were infested as frequently as adult males (older than 10 months), and there was no difference in incidence between the sexes. Worms recovered from 97 infested stoats occurred equally often in either side of the skull; were more often large (i.e., probably female) at all intensities of infestation; and numbered 1–73 per infested stoat (mean 12.9 in females, 14.2 in males; difference not significant). There was no evidence that infested stoats were smaller or lighter than uninfested onces.