A review of potential techniques for identifying individual stoats (Mustela erminea) visiting control or monitoring stations

Abstract

We review ways of individually identifying stoats (Mustela erminea) and similar small mammals from visits to bait stations or to monitoring devices in the field. Tracking devices are the cheapest and most practical method currently available of measuring the presence of a particular species, but there has been little research on the recognition of individuals. Elongation of tracking tunnels, or using sooty plates rather than ink to record prints, may improve detectability of individual markings. Recording visits to bait stations or tracking tunnels from DNA sequencing of hair or skin samples is likely to be prohibitively expensive for many monitoring programmes. Identification of stoats visiting bait stations or tracking tunnels using electronic devices has great potential, but these techniques are impracticably expensive because stoats move over such large areas that individual receivers and data loggers would be needed for each bait station. Chemical bait markers such as rhodamine B may be the most suitable method for identifying which animals have used a particular bait station.     

Seasonal variation in the diet of stoats in a breeding colony of Hutton's shearwaters

Abstract

Two advantages could be gained by developing multi-species control by aerial baiting. It should assist pest managers to achieve sustainable resource management by improving the efficiency of operations; and it should reduce the likelihood of unwanted ecological side-effects (such as prey-switching) that sometimes follow when pest species are controlled individually. The technology to achieve efficient multi-species control is already well advanced, aided particularly by the refinement of aerial control of possums and by the development of baits for individual species. More effort will, however, be required to develop predictive models for planning the integration of multi-species control with conventional single-species control, and for predicting the ecological effects of such intervention.     

Responses of stoats to scent lures in tracking tunnels

Abstract

Scent lures made from the anal sac secretions of stoats (Mustela ermined) in a long‐life formulation increased the number of visits by stoats to footprint tracking tunnels set near the shoreline of Lake Waikaremoana. Lures derived from female stoats received a similar number of visits to those derived from males. Blank lures with no active ingredient did not attract stoats. Most of the lures remained intact and active for about seven weeks in summer. Rodents were unaffected by the lures, being neither repelled by the scent of stoats, nor attracted to the edible casein‐based carrier compound. Our results suggest that scent lures could be useful for indexing stoat populations. Trials are needed to compare the effectiveness of lures and bait, and to determine seasonal changes in lure attractiveness. Problems of supply of the active ingredients will need to be overcome.     

The effects of mice on stoats in southern beech forests

Introduced stoats (Mustela erminea) are important invasive predators in southern beech (Nothofagus sp.) forests in New Zealand. In these forests, one of their primary prey species – introduced house mice (Mus musculus), fluctuate dramatically between years, driven by the irregular heavy seed‐fall (masting) of the beech trees. We examined the effects of mice on stoats in this system by comparing the weights, age structure and population densities of stoats caught on two large islands in Fiordland, New Zealand – one that has mice (Resolution Island) and one that does not (Secretary Island). On Resolution Island, the stoat population showed a history of recruitment spikes and troughs linked to beech masting, whereas the Secretary Island population had more constant recruitment, indicating that rodents are probably the primary cause for the ‘boom and bust’ population cycle of stoats in beech forests. Resolutions Island stoats were 10% heavier on average than Secretary Island stoats, supporting the hypothesis that the availability of larger prey (mice verses wētā) leads to larger stoats. Beech masting years on this island were also correlated with a higher weight for stoats born in the year of the masting event. The detailed demographic information on the stoat populations of these two islands supports previously suggested interactions among mice, stoats and beech masting. These interactions may have important consequences for the endemic species that interact with fluctuating populations of mice and stoats.     

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.     

Rhodamine B as a systemic hair marker for assessment of bait acceptance by stoats (Mustela erminea)

Abstract

Rhodamine B (RB) is a dye that becomes incorporated into the structure of growing hair of animals that ingest it, appearing as an orange‐red fluorescent band detectable under a fluorescent‐light microscope. This marker was evaluated as a means of assessing bait acceptance by stoats (Mustela erminea L.). Eleven wild‐caught captive stoats were each fed a broken hen egg injected with 25 mg of RB on two occasions, 5 weeks apart. This was equivalent to 62–108 mg kg^–1, depending upon stoat weight, on each occasion. At least three facial whiskers were collected from each dosed stoat on each of two sampling dates (giving a total of at least six whiskers from each stoat). The sampling dates varied from 1 to 17 weeks after first dosing. Whiskers were also collected from one of the dosed stoats that died of other causes 19 weeks after first dosing, and from four stoats not dosed with RB. All 11 of the stoats fed RB had at least one fluorescent band in at least one of the sampled whiskers. None of the four stoats not fed RB had fluorescent bands in their whiskers. The marking persisted in all dosed stoats for at least 6 weeks, and in one dosed stoat for at least 19 weeks after dosing. However, only 56% of the 91 whiskers inspected from the dosed stoats had fluorescent bands, and only 9% of the whiskers had two fluorescent bands, representing the two doses of RB. The distance between the two fluorescent bands indicated a mean whisker growth of 0.6 mm day^‐1. The distance from the base of the whiskers to the base of the fluorescent bands was broadly related to the time after ingestion of bait containing RB. However, the variation was too great for distance along the whisker to be reliably used as a quantitative measure of time after bait ingestion. The technique can be used to assess bait acceptance in the field provided all stoats are sampled within c. 4–6 weeks of baiting, and at least 6–9 whiskers are sampled from each stoat.     

The potential for biological control of stoats (Mustela erminea)

Abstract

Accelerating the mortality of stoats (Mustela erminea) using biological agents, or reducing their fertility using chemosterilants or biological agents, are increasingly seen as more sustainable and more humane than trapping and poisoning. Obligate delayed implantation in fertilised female stoats of all ages allows 10–11 months for an applied biological agent or chemosterilant to interfere with gestation. Two chemosterilants (cabergoline and mifepristone) disrupt pregnancy in some species and may be effective on stoats, although they are not species‐specific and are probably more expensive than poisoning. For the longer term, more recent fertility control research has explored potentially more species‐specific options for other species based on inducing an immune response to an animal's own reproductive hormones, gametes, or products from embryos. Conception will be difficult to disrupt in stoats because females are sexually mature and are mated in the nest during a short period before they are weaned. A large research effort will be required to determine which of the immunosterilants being developed could be suitable candidates for stoat control. There are fewer options apparent for using biological agents to increase stoat mortality, although species‐specific strains of canine distemper virus may be effective against stoats.

The greatest impediment to controlling stoat fertility will be effective delivery of sterilants. For the foreseeable future, it will probably be necessary to rely on baits, but they are unlikely to put all target stoats at risk, and will be incapable of delivery over larger scales than at present.

Before undertaking expensive field trials and development of anti‐fertility and biological agents, the effects of putative compensatory changes in demographics that may be associated with changes in stoat density should be modelled to see if the sterilisation and mortality rates that are required to achieve a given level of population control are realistic targets. Also, population control should be defined in terms of accrued benefit for wildlife by establishing the relationships between stoat densities and the viability of prey populations.

Biological control of fertility or mortality may never be suitable as stand‐alone control options for stoats, particularly when some native fauna survive only if stoats are reduced to very low densities. Biological control may have greater potential when integrated with conventional control.     

Predicting the incidence of mohua predation from the seedfall,mouse, and predator fluctuations in beech forests

Abstract

Predator control will be required to save many mohua (Mohoua ochrocephala) populations from extinction. However, control may be required only in years when stoat (Mustela erminea) densities are high. To manage local stoat populations effectively, a reliable predictor of high risk years is required. We examined whether different levels of beech seedfall and mouse capture rates were related to the levels of mohua predation recorded in the Hawdon Valley, Arthur's Pass National Park, and the Eglinton Valley, Fiordland National Park, between 1989 and 1994. During this period there was only one full beech mast year in each study area during autumn. The full mast seedfall in Hawdon Valley was predominantly of mountain beech (Nothofagus solandri var. cliffortioides) and red beech (N. fused), and in Eglinton Valley it was predominantly silver beech (TV. menziesii). During the following summer, mouse and stoat densities, and the predation rate of adult mohua, all increased considerably. There was very little predation on adult mohua in the summers following poor seedfalls when mouse and predator densities remained low. In 1993, a partial mast did not trigger a mouse or stoat irruption.

We conclude that counts of beech seedfall and indices of mouse density are potential predictors of an impending irruption of key predators. Winter mouse density appeared to be the most reliable indicator, because neither stoats nor mice respond to seedfall alone. A combination of these indicators could be used as a basis for management decisions on whether to undertake stoat control to protect mohua populations in the future. However, more information is required on the seedfall thresholds that may trigger sufficient increases in mouse and stoat numbers and, consequently, bird predation.     

Scats and den contents as indicators of the diet of stoats (Mustela erminea) in the Tasman Valley,South Canterbury,New Zealand

Stoats are significant predators of native fauna in New Zealand. They occur in many habitat types and consume a wide range of prey. The diet of stoats in the Tasman River, South Canterbury, was studied by analysis of scats and den contents. Analysis of 206 scats showed that stoats ate mainly lagomorphs, birds and invertebrates. Minor components included mice, lizards, fish and hedgehogs. Stoats ate more birds in spring than in autumn, and female stoats ate more invertebrates than did males. The contents of 219 dens collected in the same area at the same time provided further information. Birds and lagomorphs occurred at high frequency in dens, and other components were minor. Remains in dens were larger than in scats and allowed identification of many more prey items to species level. Den contents revealed a potentially substantial impact of stoats on threatened shorebirds locally; this impact was not detected by analysis of scats.     

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.     

Campbellenchinae (Nematoda: Tylodoridae), a new subfamily from campbell Island,with a description of two new species

The first paragraph of the Introduction serves as an Abstract.

Specimens of an undescribed subfamily of Tylodoridae Paramonov, 1967 were found in each of 50 soil samples collected since 1951 from around the roots of native plants on Campbell Island, New Zealand. This taxon, Campbellenchinae n.subfam., its type‐genus, Campbellenchus n.gen., and 2 new species, C. poae and C. filicauda, are described. The diagnostic characters of the new subfamily include a lip region without a labial disc, a stylet of moderate length, a characteristic zone of cuticular annulation anterior to the stylet knobs, a slit‐like amphidial opening, a single ovary, and a filiform tail.     

生物统计学专业课教育融合劳动教育的初步设计北大核心CSCD

当前大学教育中,劳动教育的实际施行与劳动教育的重要性仍不匹配,主要表现为劳动教育观念未与时俱进、劳动教育形式单一和劳动教育资源缺乏,与当前社会的专业性、创造性劳动需求仍有较大差距。将劳动教育与专业教育相融合将是解决上述问题的有效途径之一。两者的融合不仅可以丰富劳动教育和专业教育的教学形式,使专业教育和劳动教育互相促进,而且可以使劳动教育结合专业知识和专业技能,兼具传统劳动教育的要素和创造性劳动的时代需求。文中重点介绍了生物统计学课程教育中融合劳动教育的设计和实践方法,并分析了两者互相促进的途径及效果。     

Short pulse of 1080 improves the survival of brown kiwi chicks in an area subjected to long-term stoat trapping

Many mainland populations of kiwi are declining because stoats (Mustela erminea) kill most of their chicks. Stoats are often trapped during conservation programmes, but the long-term effectiveness of trapping has not been measured. During continuous trapping of mammalian predators in the 9800?ha Whangarei Kiwi Sanctuary, the survival of brown kiwi (Apteryx mantelli) chicks declined over time. Following the use of sodium fluoroacetate (1080) to kill rats (Rattus spp.) and possums (Trichosurus vulpecula) and likely secondary poisoning of stoats, chick survival at Riponui increased from 5% to 56%, and the 62% chick survival at Rarewarewa was better than the 20% recorded in a trapped-only area nearby. We suggest that untrappable stoats accumulate in areas subjected to continuous predator trapping. Conservation managers should build into their long-term pest control programmes a periodic pulse of an alternative tool to kill pests that, for whatever reason, actively avoid the primary control tool.     

Poor design of behavioural experiments gets poor results: examples from intertidal habitats

Many patterns of distribution and abundance of intertidal animals are explained by processes of movements of animals, selecting particular habitats or levels on the shore, or interacting with other species. Movements of intertidal animals have therefore been studied over many years. During this long history, much intertidal ecology has changed in focus from broad-scale to small-scale patterns and processes, although there has been recent refocus on a combination of many scales. Simultaneously, there has been an increase in the incidence of field experiments and growing recognition that behaviour is more flexible than originally thought. This review examines changes in the ways that experiments on movements on intertidal animals have been and are being done, taking into account these changes in emphasis. Although some progress has been made, there is still a long way to go. The idea is still prevalent that behaviour is simple, rather invariant and that the animals respond to broad-scale cues that have traditionally been of interest to many investigators. This means that many experiments are still designed to minimise (or ignore) natural variation in behaviour rather than to measure it and that any associated disturbances are considered irrelevant and therefore not evaluated. Understanding the role that behaviour has in establishing and maintaining many of the patterns observed on intertidal shores is crucial to our understanding of the ecology of these habitats. Better experiments, designed logically with appropriate controls to evaluate realistic processes and to measure how behaviour varies among places and from time to time can only improve this understanding.     

Investigating the behavioural responses of trapped fishes using underwater video surveillance

An underwater video surveillance system known as TrapCam was used to continuously record (15 ×c. 24 h periods) fish behaviour within and immediately surrounding an experimental fish trap situated in a coral reef ecosystem in the United States Virgin Islands. Of the 100 fishes (18 species, 12 families) trapped, surgeonfishes (Acanthuridae) and snappers (Lutjanidae) were most common. Thirteen distinctively identifiable behaviours were observed for trapped fishes. Species did not differ significantly in the proportion of time allocated to different behaviours (ANOSIM, R = 0·142). Doctorfish Acanthurus chirurgus and grey angelfish Pomacanthus arcuatus allocated the largest proportion of their recorded time to enter and exit the trap. Fishes spent an average of 15 min in the trap before escaping. Sixty‐seven per cent of trap approaches consisted of an individual of the same species as one already trapped suggesting that conspecific attraction may have occurred. Fifteen per cent of trapped species were observed with abrasions to the head and 70% were observed approaching the trap corners. The results of this study provide a greater understanding of the behavioural interactions between fishes and traps that can help explain patterns of catch composition, the physical condition of fishes in traps and inform design of gear modifications to optimize by‐catch reduction in the trap fishery.