Lack of movement of stoats (

Little is known about the movement of stoats in alpine grassland, where several species of native birds, reptiles and invertebrates are potentially at risk from predation. Radio-tracking, live trapping and tracking tunnel techniques were used to sample stoats in two adjacent habitats to determine whether the home range of stoats in beech forest valley floors extends into neighbouring alpine grasslands in the Ettrick Burn Valley, Fiordland. If this is the case then trapping stoats in the more easily accessible beech forest valley floors might serve to protect endangered species inhabiting the adjacent but more remote alpine grasslands. Between December 2000 and March 2001, 415 radio locations were collected on 15 stoats and none were observed to make any significant movements between the two habitats. Stoats were active in alpine grasslands, and trapping in the adjacent beech forest valley would not have caught those stoats during the time-frame of this study. Further research is needed to determine long term impacts of trapping in beech forest on stoats in alpine grasslands. During the timeframe of this research stoats were more abundant in beech forest than in alpine grasslands, and tracking tunnels showed this trend to be consistent at other sites.     

Observed responses of captive stoats (

Artificial barriers, such as nest boxes and metal collars, are sometimes used, with variable success, to exclude predators and/or competitors from tree nests of vulnerable bird species. This paper describes the observed response of captive stoats (Mustela erminea) to a nest box design and an aluminium sheet collar used to protect kaka (Nestor meridionalis) nest cavities. The nest box, a prototype for kaka, was manufactured from PVC pipe. Initial trials failed to exclude stoats until an overhanging roof was added. All subsequent trials successfully prevented access by stoats. Trials with a 590 mm wide aluminium collar were less successful, but this was mainly due to restrictions enforced by enclosure design: Stoats gained access above the collar via the enclosure walls and ceiling. In only one of twelve trials was a stoat able to climb past the collar itself. The conservation implications of these trials and directions for future research are discussed.     

Trappability and densities of stoats (

Stoat (Mustela erminea) density was estimated by live-trapping in a South Island Nothofagus forest, New Zealand, at 8-9 (Jan/Feb 1996) and 15-16 (Aug/Sep 1996) month intervals after significant beech seedfall in autumn 1995. Absolute densities were 4.2 stoats per km² (2.9-7.7 stoats per km², 95% confidence intervals) in Jan;Feb 1996 and 2.5 stoats per km² (2.1-3.5 stoats per km²) in Aug/Sep 1996. Trappability of stoats increased in the latter sampling period, probably because mice (Mus musculus) had become extremely scarce. accordingly, trapping rates of stoats may vary temporally and spatially with food supply rather than only with absolute abundance. Ship rats (Rattus rattus) capture rates doubled between Jan/Feb 1996 and Aug/Sep 1996, but rapidly declined shortly afterwards. Trappability of ship rats also increased in the latter sampling period. These factors must be considered when planning methods of indexing relative densities of stoats and rats.     

Non-invasive methods for genotyping of stoats (

Stoats (Mustela erminea) are a significant pest in New Zealand. A critical aspect of their management is the ability to identify individuals in order to estimate abundance or to determine the origin of residual animals after control, particularly as the trap-shy nature of stoats reduces the utility of trapping to gain this information. We investigated non-invasive ?capture? methods as an alternative to live-trapping or removal methods for estimating stoat abundance. First we determined whether sufficient variability exists at six microsatellite DNA loci to reliably identify individuals in the potentially bottlenecked, introduced stoat populations of New Zealand. In December 2001 we conducted a 7-night pilot field experiment using a modified hair-tube design, where we obtained a total of 64 hair samples. Sufficient DNA was extracted from 3?6 hair follicles to genotype a total of 51 samples. DNA quality declined if samples were left in the field for several nights before being collected, and daily checks proved best for maximising the quality of DNA obtained, while minimising the risk of multiple ?captures? of stoats. Conclusions were that non-invasive molecular sampling is likely to be a viable technique for estimating population density of stoats in New Zealand beech forest but that additional variable loci are required.     

Daily activity of impala

The basic activity pattern of impala in the Serengeti is described quantitatively; seasonal variations and those related to social status are discussed. The adaptiveness of the basic pattern, especially in the preponderance of vulnerable and mobile activities in the daytime and of static activities at night, is discussed. The cost of various territorial activities is stressed; the presence of females in his territory disturbs the basic activity pattern of the territorial male, reducing his time spent on feeding and ruminating. The relationship between the occurrence of males in shade and some environmental factors is analysed.     

Selection of alpine grasslands over beech forest by stoats (

Predation by introduced stoats is now considered a major threat to the population viability of several New Zealand endemic bird species. Historically stoat research and management has focused on beech forests and little is known about the ecology of stoats in the alpine grasslands occurring above the natural altitudinal limit of beech forest. Several stoat control operations in beech forest valley floors in southern New Zealand assume that adjacent montane areas act as a barrier to stoat immigration. Stoats were live-trapped and radio-tracked in alpine grasslands above the Borland Burn, Fiordland National Park, during the summer and autumn of 2003 and 2004. Seventeen stoats were radio-collared and home ranges were estimated for 11 of them. These home ranges were used in a compositional analysis which showed that these stoats spent significantly more time in alpine grassland than in adjacent beech forest. Range cores calculated for six of these stoats were located high up in alpine grassland and contained very little beech forest. This means that montane areas that contain alpine grasslands are unlikely to be barriers to stoat immigration; rather they may be a source of dispersing stoats that reinvade control areas. Also, endemic animal species that inhabit alpine grasslands could be at risk from stoat predation.     

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.     

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.     

Captive husbandry of stoats Mustela erminea

Abstract

Captive stoats are essential for testing technological developments for pest control in New Zealand. We have reviewed husbandry practices and experiences of keeping stoats in captivity for a range of purposes. Stoats can be kept individually outside and subjected to normal regimes of light and temperature if sufficient bedding and shelter is provided. They appear to survive and breed best when fed on freshly killed rodents. Live prey is desirable though will rarely be permissible due to regulatory constraints. Breeding in captivity has been problematic in most cases, and although in a few instances wild‐caught females carrying embryos in delay have given birth, this is a rare event. Procedures taken to minimise stress in captivity may reduce the loss rate of blastocysts due to resorption and facilitate rapid expansion of captive colonies.     

Daily rhythms of locomotor activity in some Carabidae (Coleoptera)

The daily cycle of activity was investigated in a number of species of Carabidae. Most were either nocturnal or diurnal, but some were plastic and responded to environmental conditions.

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Résumé Le cycle quotidien de l'activité des mouvements fut étudié chez plusieurs espèces de Carabidae par observations d'élevage en insectarium.L'auteur a trouvé que la majorité des espèces pourraient être classées strictement comme nocturnes ou diurnes.Certaines espèces furent classées comme indifférentes, le cycle journalier de leur activité variant en fonction des modifications naturelles du milieu externe.

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This work formed part of a thesis submitted for the degree of Doctor of Philosophy in the University of London.     

Daily activity and body temperature

Body temperature varies between 36 and 39° C in states ranging from sleep to high levels of sustained exercise, but it is not known whether this continuum of body temperature is related to a continuum of activity. Calorimetric studies of sedentary days were undertaken with four levels of food intake, men doing mild sustained exercise, and men and women walking and cycling vigorously. Steady states of metabolism were followed by slow exponential changes to steady states of heat loss (Q), followed in turn by changes in rectal temperature (T _re). Regression analysis showed a continuous, curvilinear relationship between Q andT _re from the low end of the activity spectrum (50 W) to progressively higher levels of exercise (600 W). These related continua of activity and body temperature appear to be the result of heat regulation.     

Using genetics and Bayesian modelling to evaluate the eradication of stoats (

The New Zealand Department of Conservation recently (May 2008) began a programme to eradicate stoats (Mustela erminea) from Resolution Island (Fiordland, New Zealand) using kill traps. In conjunction with this eradication effort we have the following 3 objectives: (1) to measure the population abundance of stoats prior to trapping using hair tubes and forensic DNA methods; (2) optimise techniques for detecting individual stoats, in order to quantify the probability of stoat persistence given no detections after several months of trapping; and (3) use genetic analyses to identify the possible origins (mainland incursions or in situ breeding) of new stoats captured in a control zone. We present Bayesian modelling techniques used to determine the probability of stoat persistence on the island after the initial population reduction, when individual stoats are no longer captured in traps. We also provide details on an effective level of monitoring and trapping effort required to maintain a comfortable level of confidence that stoats no longer persist on the island. Improving these techniques adds to variety of valuable tools for management of invasive mammal species in a range of natural environments worldwide.     

Food habits of British stoats (Mustela ermined) and weasels (Mustela nivalis)

Information on the food habits of stoats and weasels was obtained chiefly from gut analyses of carcasses sent from various parts of Britain. Lagomorphs, small rodents and birds form the bulk of the food taken by these predators. The three food classes appear to be equally important to stoats, whereas weasels obtain nearly half of their food from small rodents. Microtus was the most important small rodent in the diet of both stoats and weasels. Game birds were taken more by stoats than weasels; the chief bird prey of the latter was passerines.     

Daily activity timing in the Anthropocene

Animals are facing novel ‘timescapes’ in which the stimuli entraining their daily activity patterns no longer match historical conditions due to anthropogenic disturbance. However, the ecological effects (e.g., altered physiology, species interactions) of novel activity timing are virtually unknown. We reviewed 1328 studies and found relatively few focusing on anthropogenic effects on activity timing. We suggest three hypotheses to stimulate future research: (i) activity-timing mismatches determine ecological effects, (ii) duration and timing of timescape modification influence effects, and (iii) consequences of altered activity timing vary biogeographically due to broad-scale variation in factors compressing timescapes. The continued growth of sampling technologies promises to facilitate the study of the consequences of altered activity timing, with emerging applications for biodiversity conservation.     

Trapping tunnel design incorporating behavioural preferences of stoats

Abstract

Stoats (Mustela erminea) are introduced pests in New Zealand, and there is an urgent need for effective trapping systems that kill the animal in a humane manner. A treadle trap was designed, the Dominus trap, that utilised an earlier‐proven humane killing system enhanced by the addition of a treadle plate trigger. This system enabled the trap to be classified as a Class A trap under the National Animal Welfare Advisory Committee (NAWAC) guidelines for animal kill traps, by successfully rendering 10/10 animals unconscious within 30 s. The Dominus trap mimics a tunnel, which by its very shape entices the animal to enter, but weighs only 600 g. Atrial at Flea Bay, on Banks Peninsula, used 35 Dominus traps placed alternately between 35 Fenn Mk VI traps set over 3150 trap nights (TN). The trial was conducted from March to May 2007 and was repeated for a further 7740 trap nights from January to March 2008, using 20 Dominus traps. The Dominus trap caught stoats consistently at the rate of 0.22 stoats/100 TN in both years, compared with 0 and 0.14/100 TN in Fenn traps, so potentially provides a humane alternative to the Fenn.