We combine model results with field data for a system of wolves ( Canis lupus ) that prey on wild boar ( Sus scrofa ), a wildlife reservoir of tuberculosis, to examine how predation may contribute to disease control in multi-host systems. Results show that predation can lead to a marked reduction in the prevalence of infection without leading to a reduction in host population density since mortality due to predation can be compensated by a reduction in disease induced mortality. A key finding therefore is that a population that harbours a virulent infection can be regulated at a similar density by disease at high prevalence or by predation at low prevalence. Predators may therefore provide a key ecosystem service which should be recognised when considering human-carnivore conflicts and the conservation and re-establishment of carnivore populations.

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Canine adenovirus type 1 (CAdV-1) is responsible for infectious canine hepatitis. The disease has been described in captive American black bear (Ursus americanus) and European brown bear (Ursus arctos arctos), with just one recently reported case in a cub of a free-ranging brown bear (Ursus arctos horribilis) from Alaska. The aim of this work is to summarize findings related to presence and associated mortality of CAdV-1 in 21 free-ranging Cantabrian brown bears (Ursus arctos arctos) submitted to necropsy in Asturias and Castilla y León (northwestern Spain) from 1998 to 2018. On the basis of the anatomopathological findings and laboratory results three free-ranging brown bears died due to infectious canine hepatitis, which is to our knowledge the first description of death due to this disease in free-ranging bears in Europe. Gross lesions consisted of petechial haemorrhages and congestion in different internal organs, haemorrhagic fluid in internal cavities, friable and yellowish liver and thickening of gall bladder. Microscopic lesions were observed mainly in liver, kidney and brain and consisted of multifocal necrosis of cells with presence of basophilic intranuclear inclusions. Immunohistochemical (IHC) and real-time polymerase chain reaction (qPCR) techniques were used to assess the presence of CAdV-1 in paraffin-embedded liver samples. Viral antigens were detected by IHC labelling within hepatocytes and Küppfer cells in the three animals. The presence of viral DNA was confirmed by qPCR in one of them. In order to evaluate the circulation of CAdV-1 in brown bears, a retrospective study was performed using both IHC and qPCR techniques in 11 and 12 additional brown bears, respectively. An extra brown bear was found positive by IHC. This study shows that CAdV-1 surveillance of brown bears and sympatric carnivores should be considered as major concern for the monitoring the population evolution throughout time in this endangered species.

Reliable methods to measure stress-related glucocorticoid responses in free-ranging animals are important for wildlife management and conservation. Such methods are also paramount for our ability to improve our knowledge of the ecological consequences of physiological processes. The brown bear (Ursus arctos) is a large carnivore of ecological and cultural importance and is important for management. Here, we provide a physiological validation for an enzyme immunoassay (EIA) to quantify glucocorticoid metabolites in brown bear feces. We also provide an evaluation of the effects of sample exposure to ambient temperature on measured fecal glucocorticoid metabolite (fGCM) concentrations. We evaluated three EIA systems: a cortisol assay, an 11oxoetiocholanolone assay, and an 11b-hydroxyetiocholanolone assay. Of these, the cortisol assay provided the best discrimination between peak fGCM concentrations detected 1-4 d after injections of synthetic adrenocorticotrophic hormone and preinjection baseline concentrations in four individual brown bears. The time of exposure to ambient temperature had substantial but variable effects on measured fGCM concentrations, including variation both between samples from the same individual and among samples from different bears. We propose that the validated EIA system for measuring fGCM concentrations in the brown bear could be a useful noninvasive method to monitor stress in this species. However, we highlight that this method requires that fecal samples be frozen immediately after defecation, which could be a limitation in many field situations.

The number of wild animals threatened or at risk of extinction constantly increases and, as a result, biodiversity decreases. Therefore, it is necessary to set in motion proceedings to preserve the genetic variability and to overcome factors leading to this situation. Banks of cryopreserved cells, such as skin fibroblasts, from wild animals could be used both for genetic studies and as a cell source for technologies able to reproduce individuals. In this study we report that a single basic protocol provides a method for obtaining, culturing, and cryopreserving skin fibroblasts from a wide range of wild animals. Skin biopsies were taken in Cantabria (Spain) from live, anesthetized brown bear (Ursus arctos, n = 4), and in Asturias (Spain) from carcasses of accidentally killed individuals from the following species: grey wolf (Canis lupus, n = 1), red fox (Vulpes vulpes, n = 1), eurasian badger (Meles meles, n = 1), ermine (Mustela erminea, n = 1), fallow deer (Dama dama, n = 7), pyrenean chamois (Rupicapra pyrenaica, n = 1), western roe deer (Capreolus capreolus, n = 1), wild boar (Sus scrofa, n = 1), striped dolphin (Stenella coeruleoalba, n = 1) and one avian species, capercaillie (Tetrao urogallus, n = 1). Once obtained and transported to the laboratory, all samples were processed identically. Tissue samples were manually cut into small pieces and enzymatically digested with 0.05% trypsin-EDTA (Sigma-Aldrich, Madrid, Spain) for 30 min, and then with collagenase (300 units/mL) (Sigma) for 14 h at 38°C. Disaggregated cells were centrifuged at 1600 rpm for 10 min and the pellet was diluted with D-MEM (Sigma) containing 10% FBS. Cells were counted and a minimum of 3 × 105 cells were placed in a 25 cm2 flask for culture under 5% CO2 in air and high humidity at 37°C (red fox, badger, ermine, western roe deer) or 38°C (brown bear, grey wolf, fallow deer, pyrenean chamois, wild boar, striped dolphin, capercaillie). Confluent fibroblast monolayers were obtained after 5–7 days in culture except for the striped dolphin whose sample was contaminated. Two to three passages were performed using 75 cm2 flasks before freezing fibroblasts in D-MEM containing 10% DMSO (Sigma) and 10% FBS. Total cell yield from a confluent flask was 5–11 × 106 cells, depending on the animal species. Fibroblasts recovered from all thawed samples grew to confluence, and karyotypes were performed at this step. It was possible to obtain, culture, freeze, and thaw skin fibroblasts successfully from all the above-mentioned land species. Although more research is needed, preliminary data suggest that the above-described procedure can be applied to mammals and birds, thus helping to preserve genetic material of wild animals. Grant Support: Consejería de Medio Ambiente, Ordenación del Territorios e Infraestructuras, Asturias, SPAIN. The authors acknowledge CEPESMA, Luarca, Asturias, SPAIN.