Costs and benefits of aerial 1080 possum control operations using carrot baits to North Island robins (

We monitored the behaviour of 62 radio-collared ferrets and 25 radio-collared cats in dry, tussock grassland habitat in New Zealand's South Island. The total home range of adult male ferrets (102 ± 58 ha, mean ± 1 s.d.) was marginally greater than that of females (76 ± 48 ha), and averaged 90 ± 55 ha. Male ferret core ranges (27 ± 15 ha) were larger than those of females (16 ± 8 ha). Adult cat home ranges were similar between sexes, and were larger and more variable than those of ferrets (225 ± 209 ha). Core range size of cats was similar between sexes and averaged 54 ± 24 ha. The upper 95% confidence limits of the mean home range lengths of adult ferrets and cats were 2.7 km and 5.1 km, respectively, indicating the width of buffer zones where predator control should be extended to protect the boundaries of areas targeted for predator control in dry, tussock grasslands. Although core areas were mostly discrete, home ranges were distributed randomly, and animals that shared space neither avoided nor attracted each other. Little evidence of territoriality may be related to high densities of primary prey. Too few cats were monitored to determine territoriality. Ferrets used at least 9.4 ± 3.2 dens, and cats used 11.5 ± 3.0 dens during the study. Although 71% of dens were used only once, some were used up to nine times. Day time resting by ferrets was mostly solitary. If transmission of bovine Tb occurs between adult ferrets, simultaneous sharing of dens during the day is unlikely to be a significant mode of transmission in this habitat. We were unable to determine the extent of den sharing by cats. Cats occupied den sites with more shrubs and rocks compared with ferrets. Predator control stations in dry tussock grassland habitat may therefore be more effective at killing cats than ferrets if placed in shrubby, rocky areas.     

Characterization of transforming growth factors beta1 and 2 in ferrets (Mustela putorius furo)

Unwanted scar tissue after surgical procedures remains a central problem in medicine. Nowhere is this problem more evident than within the pediatric airway, where excess scarring, termed subglottic stenosis, can compromise breathing. Recent advances in molecular biology have focused on ways to decrease scar formation through understanding of the wound repair process. Transforming growth factor beta (TFGbeta) plays a central role in this pathway. Ferrets serve as an ideal model for the pediatric airway, and reproduction of subglottic stenosis in ferrets is possible. However, ferret cytokine profiles have not been established. In this study, we characterized the presence and nucleotide sequence of the TGFbeta1 and 2 genes in ferrets by using total RNA isolated from airways. Amino acid sequence homology between human and ferret was determined to be 96.6% for TGFbeta1 and 99.3% for TGFbeta2. Given the nearly total homology between TGFbetas of ferret and human origin, the ferret may serve as an ideal model for future molecular studies.     

Intraspecific and seasonal differences in the diet of feral ferrets (

This study reports the diet of feral ferrets (Mustela furo) in a pastoral habitat, East Otago, South Island, New Zealand. Rabbits (Oryctolagus cuniculus) were the most common prey of ferrets, occurring in 86.7% of seats, but birds (12.4%) and invertebrates (11.3%) were also frequently eaten. Female ferrets ate more non-lagomorph prey items, especially invertebrates and birds than males. No significant dietary differences were found between juvenile and adult ferrets except in summer when juveniles ate more lagomorph prey. There were seasonal differences in the consumption of rabbits, invertebrates, skinks, possums (Trichosurus vulpecula) and small and large secondary prey items. Seasonal differences in ferret diet are likely to be related to the relative abundance of the various prey items. Lagomorph availability may also be a determinant of the frequency of occurrence of other prey items in the diet. Dietary differences may differentially influence the functional response of adults and juveniles and/or males and females to rabbit control or other manipulations of prey populations. Bovine tuberculosis (Mycobacterium bovis) infections in ferret populations show intraspecific variation with more males than females and more adults than juveniles infected. Intraspecific dietary differences in diet were not observed in the species (possums and hedgehogs (Erinaceus europaeus)) considered to be the main sources of infection for ferrets.     

Denning Chronology and Design of Effective Bear Management Units

Abstract: Reports on the effectiveness of using late fall hunting seasons to reduce the proportion of female black bears (Ursus americanus) in the harvest are limited, and the geographic scale over which the technique functions as intended has not been examined. During 1992-2000, we radio-equipped black bears in New Mexico, USA, obtained estimates of 175 den entry and 137 den emergence dates, and used New Mexico Department of Game and Fish harvest data (1985-2000) to test for differences in proportion of females in the harvest relative to denning chronology. Bears in northern New Mexico entered dens earlier and emerged later than bears in southern New Mexico (P ≤ 0.001). In northern New Mexico bears displayed the typical pattern of earlier entry and later emergence by reproductive females, proportion of females in the harvest varied over time as expected, and late fall seasons were effective (P < 0.10). In contrast, denning chronology did not differ by sexin southern New Mexico, proportion of females in the harvest did not change over time, and late fall seasons were not effective (P ≤ 0.18). Manipulation of hunting season dates to influence female mortality can be an effective tool, however our study provides an example of an area where denning chronology did not differ by sex and late seasons were not effective. We also observed regional differences in timing of entrance and emergence, which suggest that scale of application may be key. In management jurisdictions that encompass ecologically distinct areas, cover a wide range of latitudes, or are mountainous, successful use of the technique may depend on knowledge of denning chronology at multiple locations and appropriate designation of hunting unit boundaries, season dates, and data analysis units.     

Long-term impacts of grazing on indigenous forest remnants on North Island hill country, New Zealand

Small isolated patches of native forest surrounded by extensive pastoral grasslands, characteristic of many New Zealand rural landscapes, represent an important reservoir of lowland biodiversity. Improved management of them is a major focus of biodiversity conservation initiatives in New Zealand. We quantified the long-term impacts of grazing on indigenous forest remnants in hill country at Whatawhata, western Waikato, North Island. Structure and composition were compared between forest fragments grazed for >50 years and nearby ungrazed continuous forest. Grazed fragments had shorter and less shady canopies, sparser understoreys, tree populations with larger mean diameters, and ground layers with lower cover of litter and higher cover of vegetation and bare soil than continuous forest. Fragments also had lower indigenous-plant species richness, especially in sapling and seedling populations, and almost no palatable indigenous shrubs, terrestrial orchids, and ferns that require high humidity (e.g. Hymenophyllum spp.), but contained many indigenous and adventive herbaceous species. A transition appears to be occurring in grazed fragments from tall, long-lived trees like Beilschmiedia tawa and Dysoxylum spectabile to short and shorter-lived trees like Kunzea ericoides, Melicytus ramiflorus, and Dicksonia squarrosa. Because grazing inhibits most regeneration processes, unfenced remnants of conifer–broadleaved forest are unlikely to be maintained in grazed pasture in the long term.     

Daily activity of stoats (

This radio-tracking study reports the daily activity rhythms in autumn and spring of 11 stoats (Mustela erminea) (9 male, 2 female), 20 ferrets (M.furo) (8 m, 12 f) and 11 feral house cats (Felis catus) (7 m, 4 f) resident on coastal grassland, Otago Peninsula, New Zealand. Activity rhythms differed markedly amongst individual stoats in autumn, but little amongst individual cats and ferrets in either season. Stoats were equally active day and night in autumn, but were more active at day than at night in spring. Cats showed moderate day activity, but were mainly active at night in both seasons. Ferrets showed low activity during daylight in autumn and were entirely nocturnal in spring. Overall, stoats were more active during daylight than cats or ferrets; and cats were more active during daylight than ferrets. Therefore, cats and especially stoats may pose the main predation threat to diurnal native species in New Zealand. Effective biological control of rabbits (Oryctolagus cuniculus) may effect the absolute abundance and daily activity of the predators, so is impossible to predict the overall impact of predation on diurnal and nocturnal native species.     

Polar bear (<Emphasis Type="Italic">Ursus maritimus</Emphasis>) maternity den distribution in Svalbard,Norway

The aim of the current study was to identify maternity denning areas and to describe aspects of denning behaviour in polar bears (Ursus maritimus) in Svalbard, Norway. Den observations made during aerial and ground surveys (n = 553), observations of recently emerged family groups made during capture and tagging of bears (n = 206), and dens recorded by satellite telemetry (n = 76 dens) were used to describe the distribution of dens in the Barents Sea region. Data were collected during March, April, and May from 1972 to 2010, and while most dens were abandoned during the first 2 weeks of April, there was substantial variation. The highest number of dens was recorded on the islands in the eastern and northern parts of Svalbard with fewer dens found further west on the island Spitsbergen. Females with cubs-of-the-year or their tracks indicated some denning in southern, eastern, and northern parts of Spitsbergen. Telemetry also revealed that females captured in Svalbard and the Barents Sea den in Franz Josef Land, Russia. The majority of dens (62%) in Svalbard were located on land within ca. 1 km of the shore with the most inland den 19 km from shore. Heavy exploitation of polar bears before 1973, when a hunting moratorium was implemented, likely led to reduced denning in some areas. Our observations of den distribution indicate that denning is now more widespread in the archipelago than 50 years ago and reflects a reestablishment of denning areas following years of protection.     

Issues to consider for preparing ferrets as research subjects in the laboratory

The domestic or European ferret (Mustela putorius furo) has been domesticated for thousands of years. Ferrets have been used for hunting and fur production, as pets, and as models in biomedical research. Despite the relatively small numbers used in the laboratory, ferrets have some unique applications including study of human influenza and severe acute respiratory syndrome (SARS)-associated corona virus. They have served as models for peptic ulcer disease, carotenoid metabolism, cystic fibrosis, and drug emesis screening, among others. Most research ferrets are males, due to estrus-related health problems in females. They may be housed conventionally and are easy to care for when their biology and behavior are understood. Due to the small number of ferret suppliers, animals are often shipped long distances, requiring air transport and intermediate handlers. It is important to minimize shipment stress, especially with weanling and pregnant animals. Additional expertise is required for success with pregnant and whelping ferrets and for rearing of neonates. The animals have specific dietary requirements, and proper nutrition is key. Successful housing requires knowledge of ferret behaviors including social behavior, eating habits, a general inquisitive nature, and a species-typical need to burrow and hide. Regular handling is necessary to maintain well-being. A ferret health care program consists of physical examination, immunization, clinical pathology, and a working knowledge of common ferret diseases. Various research methodologies have been described, from basic procedures such as blood collection to major invasive survival surgery. Ferrets have a distinct niche in biomedical research and are hardy animals that thrive well in the laboratory.     

Factors Predicting Den Use by Maternal Giant Pandas

ABSTRACT We studied the denning ecology of giant pandas (Ailuropoda melanoleuca) in the Foping Nature Reserve, China. We identified 17 used and 21 unused cavities of appropriate size to accommodate denning and measured several variables potentially affecting the suitability of these cavities for panda denning. Principal component analysis, combined with traditional univariate tests, indicated that maternal females preferred deeper cavities with a high interior-to-entrance ratio for height and width, suggesting a preference for narrow entrances and roomy chambers. Microhabitat features, including slope and distance to water, were also useful in predicting den use by maternal females. We believe that the availability of suitable dens may limit population size, especially in areas where tree dens have been eliminated by logging of old growth forests. Conservation managers in giant panda reserves can use our data to determine the number of suitable panda dens that are in an area, estimate whether there are enough for the adult female population to use as birthing dens, and—if needed—construct suitable artificial dens to increase the rate of reproduction.     

Hierarchical Den Selection of Canada Lynx in Western Montana

Abstract We studied den selection of Canada lynx (Lynx canadensis; hereafter lynx) at multiple ecological scales based on 57 dens from 19 females located in western Montana, USA, between 1999 and 2006. We considered 3 spatial scales in this analysis, including den site (11-m-radius circle surrounding dens), den area (100-m-radius circle), and den environ (1-km radius surrounding dens). Lynx denned in preexisting sheltered spaces created by downed logs (62%), root-wads from wind-thrown trees (19%), boulder fields (10%), slash piles (6%), and live trees (4%). Lynx preferentially selected den sites with northeasterly aspects that averaged 248. Average distance between dens of 13 females monitored in consecutive years was 2,248 m, indicating low den site fidelity. Lynx exhibited habitat selection at all 3 spatial scales. Based on logistic regression, den sites differed from the surrounding den areas in having higher horizontal cover and log volume. Abundant woody debris from piled logs was the dominant habitat feature at den sites. Lynx generally denned in mature spruce-fir (Picea-Abies) forests with high horizontal cover and abundant coarse woody debris. Eighty percent of dens were in mature forest stands and 13% in mid-seral regenerating stands; young regenerating (5%) and thinned (either naturally sparse or mechanically thinned) stands with discontinuous canopies (2%) were seldom used. Female lynx selected den areas with greater spruce-fir tree basal area, higher horizontal cover, and larger-diameter trees compared to random locations within their home range. Lynx selected den environs in topographically concave or drainage-like areas, and farther from forest edges than random expectation. Maintaining mature and mid-seral regenerating spruce-fir forests with high horizontal cover and abundant woody debris would be most valuable for denning when located in drainages or in concave, drainage-like basins. Management actions that alter spruce-fir forests to a condition that is sparsely stocked (e.g., mechanically thinned) and with low canopy closure (<50%) would create forest conditions that are poorly suitable for lynx denning.     

Finding the right home: distribution of food resources and terrain characteristics influence selection of denning sites and reproductive dens in arctic foxes

We examined 83 arctic fox (Alopex lagopus) dens on Bylot Island (Canada) during the summers of 2003–2005, to determine how arctic foxes select a denning site among potential sites, and a breeding den among existing dens. We compared denning sites to random locations in a 425 km² study area (landscape scale) and to other potential denning sites in a 100 m radius (local scale). Dens were located on mounds or in slopes and were closer to streams than expected. Sites with low snow cover in spring, high ground temperature, high depth to permafrost, and steep and southerly exposed slopes were preferred. Of the 83 dens, 27 were used at least once for reproduction from 2003 to 2005. We show with a resource selection function analysis that an attractive force (distribution of food resources) and an apparently repulsive one (presence of other dens in the vicinity) affected selection of dens for reproduction. We generate testable hypotheses regarding the influence of food and social factors on the denning ecology of arctic foxes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Dracunculus insignis: experimental infection in the ferret, Mustela putorius furo

The laboratory study of dracunculiasis has suffered from the lack of a suitable, readily available animal model. We have been able to experimentally infect ferrets. Mustela putorius furo, with the North American dracunculid, Dracunculus insignis. Ferrets were inoculated with 75 to 100 infective larvae and were necropsied 90 to 240 days later. Guinea worms were recovered from 10 (56%) of 18 ferrets. A total of 44 worms were recovered, for an average of 4.4 worms per infected ferret. Gravid female worms were recovered as early as 128 days postinoculation. Thirteen (87%) of 15 gravid female worms were recovered from the extremities. Living male worms were recovered at 200 days of age, indicating that not all male worms die shortly after mating. First-stage larvae recovered from gravid females as early as 200 days of age were found to be infective to the copepod, Acanthocyclops vernalis. These observations suggest that the ferret is an excellent laboratory animal for dracunculiasis research.     

Restoration of mountain beech (

Fire occurs relatively frequently in beech (Nothofagus) forest in drought prone eastern areas of the South Island, New Zealand. Because beech is poorly adapted to fire, and is slow to regenerate, forest is normally replaced by scrub or grassland. Seeding was investigated as a means of restoring mountain beech (N. solandri var. cliffortioides) forest after fire destroyed 300 ha of forest at Mt. Thomas, Canterbury, in 1980. A mixture of mountain beech, Leptospermum scoparium and other small tree and shrub species was sown within a year of the fire in the presence and absence of pasture species as a cover crop, and fertiliser. Seeding of mountain beech and L. scoparium was successful, but other species were of limited success. Competition from pasture species inhibited establishment of all native species. Fertiliser increased L. scoparium plant numbers in the first year but had no other beneficial effect on establishment of native species. Leptospermum scoparium provided a dense shrub cover in plots where the native species were sown in the absence of pasture species, but mountain beech had begun to overtop the shrub canopy by 20 years after seeding. Browsing by insects or small animals in the first 2 years is suggested as the main cause of mortality in mountain beech. Mountain beech seeded at 1.4 kg/ha resulted in about 1800 saplings/ha at age 20. It is suggested that seeding the wider burn area more than 2 years after the fire would have been unsuccessful because of competition from herbaceous species, especially Agrostis capillaris, which rapidly invaded the burnt area. A strategy is outlined for establishing mountain beech over large areas when limited quantities of seed are available.     

Landward and eastward shift of Alaskan polar bear denning associated with recent sea ice changes

Polar bears (Ursus maritimus) in the northern Alaska region den in coastal areas and on offshore drifting ice. We evaluated changes in the distribution of polar bear maternal dens between 1985 and 2005, using satellite telemetry. We determined the distribution of maternal dens occupied by 89 satellite collared female polar bears between 137°W and 167°W longitude. The proportion of dens on pack ice declined from 62% in 1985–1994 to 37% in 1998–2004 (P = 0.044) and among pack ice dens fewer occurred in the western Beaufort Sea after 1998. We evaluated whether hunting, attraction to bowhead whale remains, or changes in sea ice could explain changes in den distribution. We concluded that denning distribution changed in response to reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season. In consort, these changes have likely reduced the availability and quality of pack ice denning habitat. Further declines in sea ice availability are predicted. Therefore, we expect the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the Alaska coast in advance of denning.     

Metagenomic Analysis of the Ferret Fecal Viral Flora

Ferrets are widely used as a small animal model for a number of viral infections, including influenza A virus and SARS coronavirus. To further analyze the microbiological status of ferrets, their fecal viral flora was studied using a metagenomics approach. Novel viruses from the families Picorna-, Papilloma-, and Anelloviridae as well as known viruses from the families Astro-, Corona-, Parvo-, and Hepeviridae were identified in different ferret cohorts. Ferret kobu- and hepatitis E virus were mainly present in human household ferrets, whereas coronaviruses were found both in household as well as farm ferrets. Our studies illuminate the viral diversity found in ferrets and provide tools to prescreen for newly identified viruses that potentially could influence disease outcome of experimental virus infections in ferrets.     

The effects of forest fires on polar bear maternity denning habitat in western Hudson Bay

The effects of forest fires on polar bear (Ursus maritimus) maternity denning habitat in western Hudson Bay were determined by comparing the physical characteristics of 48 burned and 101 unburned maternity den sites from September 2001 to October 2003. Fire significantly altered vegetation composition and increased the depth of the active layer, resulting in a decrease in the stability of den sites, the collapse of dens, and degradation of the surrounding habitat. Although bears investigated burned areas, analysis of mark and recapture data, satellite telemetry, radio-telemetry, and field observations all demonstrated that bears did not use burned areas for denning. While peat denning habitat is likely not limiting at this time, the re-use and occupancy of peat den sites during the summer may be an important means of energy conservation for pregnant female bears in western Hudson Bay. Increased energy expenditures in association with increased search times for suitable den sites and the excavation of new dens can potentially affect reproductive success. Predicted increases in forest fire activity as a result of climate change, along with the long-term recovery of denning habitat may reduce the amount of suitable denning habitat in the future. Resource managers need to be aware of the possibility of a shift in the distribution of denning bears and further loss of maternity denning habitat in western Hudson Bay.     

Alopecia attributed to neoplastic ovarian tissue in two ferrets

Ferrets with adrenal gland dysfunction have alopecia as their most common clinical sign of disease. Two cases of alopecia in neutered female ferrets are reported that were associated instead with neoplastic tissue found at the site of an ovarian pedicle. Androstenedione and 17-hydroxyprogesterone, but not estradiol, concentrations were high in both ferrets. Following surgical resection of the abnormal tissue in one ferret, the high hormone values decreased quickly and hair regrowth ensued. In both cases, histologic examination revealed features consistent with classical sex cord-stromal (gonadostromal) tumors: prominent spindle cells, along with polyhedral epithelial cells and cells with vacuolated cytoplasm. Although similiar cell types have been described in the adrenal glands of ferrets with adrenal-associated endocrinopathy, an ovarian origin for the current neoplasms is considered likely on the basis of their anatomic location; accessory adrenal tissue has only been described close to an adrenal gland or in the cranial perirenal fat of ferrets. Immunohistochemical analysis, using an antibody against Mullerian-inhibiting substance, failed to prove definitively the source of the steroidogenic cells.     

Immunoprophylaxis of respiratory syncytial virus infection in the infant ferret.

Infant ferrets can be protected from respiratory syncytical virus challenge at 3 days of age by gestational infection of their mothers. Ferrets acquire their immunity to respiratory syncytial virus postpartum via immunizing products of lactation. The level of protection against viral replication correlates with the maternal serum neutralizing titer or a concomitant factor. Passive administration of adult ferret serum with a neutralizing titer of 1:1024 or greater, either i.p. or orally does not confer immunity. A nonantibody-mediated protective mechanism appears to play an important role in protecting the infant ferret from respiratory syncytial virus replication. Our findings allow the testing of the efficacy of future human vaccines before human clinical trial.     

Black Bears Select Large Woody Structures for Dens in Southeast Alaska

Timber interests target coastal temperate rainforests, and within them stands composed of large trees potentially selected by American black bears (Ursus americanus) for denning. We identified the location of 75 black bear dens (used ≥14 days) in an intensively logged area on Prince of Wales Island, Alaska, USA. We ground-visited a subset (n = 43) of these sites to measure the diameter of living trees and woody structures used by black bears for denning. We contrasted dens with random trees available in the study area in a series of models to characterize black bear den selection. All but 1 of 43 ground-visited dens were located within woody structures, and all but 2 of these structures were >1 m diameter at breast height (dbh). We built resource selection functions (RSFs) to investigate black bear den selection across a range of spatial scales, though estimated selection was generally scale invariant. Black bears strongly selected large-diameter woody structures (dead or alive) as dens at the home-range scale, with the estimated relative strength of selection (RSS) for a 2-m-diameter tree approximately 166 times that of a 1-m-diameter tree. The estimated RSS of logged forest was unexpectedly greater (2.75 times) than that of the remaining commercially valuable old-growth forest. Selection for den structures within stumps in previously logged stands suggests features of the woody structure may be of greater importance to black bears selecting dens than attributes of the surrounding forest. There was no observed correlation between bear den selection and second-growth age, indicating that stumps may persist as suitable dens well after logging. Because denning is an important part of their life history and the denning structures used by black bears on Prince of Wales Island will eventually decay, retaining habitat value for bears in areas intensively managed for timber harvest requires strategies to recruit very large, old trees throughout the landscape. © 2021 The Wildlife Society.