Non-invasive surveillance of shared pathogens in the Eurasian brown bear (Ursus arctos) human interface.

Multi-host communities are perfect scenarios for the emergence and spread of pathogens, threatening the recovery of endangered, isolated, or inbred populations, such as the brown bear (Ursus arctos) in northwestern Spain. The population recovery in recent years has forced bears to occupy highly anthropized areas, increasing their interaction with human and domestic animals, with potential consequences for global health. During 2022-2023 a survey of parasites, bacteria and viruses shared between wildlife, domestic animals and humans was performed in this population using non-invasive surveillance, i.e., bear fecal samples (n = 73) and sponge-based sampling of trees (n = 42; 14 rubbed trees and 28 control trees). Pathogen detection rates were defined as the percentage of qPCR or culture-positive samples. Generalized linear models were fitted to assess their relationship with environmental variables including dispersion of the human population, and percentage of agricultural and periurban habitats in a 6 km-buffer around each sample. Canine Adenovirus type 1 (45.2%), Giardia spp. (15.1%), Salmonella spp. (12.3%), and extended-spectrum-beta-lactamases (ESBL) Escherichia coli (1.4%) were identified in fecal samples. In contrast, only five sponges from three rubbed and two control trees resulted positive to E. coli (14.3%). The results suggest that several pathogens are common in the Cantabrian brown bear population and that anthropization of the territory modulates their prevalence and richness. The effective design of management programs for bear conservation will require a one-health approach, in which genetic analysis of non-invasive samples can be key tools for the sanitary surveillance at the wildlife-livestock-human interface.

Modelling the creation of friends and foes groups in small real social networks.

Although friendship networks have been extensively studied, few models and studies are available to understand the reciprocity of friendship and foes. Here a model is presented to explain the directed friendship and foes network formation observed in experiments of Mexican and Hungarian schools. Within the presented model, each agent has a private opinion and a public one that shares to the group. There are two kinds of interactions between agents. The first kind represent interactions with the neighbors while the other represents the attitude of an agent to the overall public available information. Links between agents evolve as a combination of the public and private information available. Friendship is defined using a fitness function according to the strength of the agent's bonds, clustering coefficient, betweenness centrality and degree. Enmity is defined as very negative links. The model allows us to reproduce the distribution of mentions for friends and foes observed in the experiments, as well as the topology of the directed networks.

New threats in the recovery of large carnivores inhabiting human-modified landscapes: the case of the Cantabrian brown bear (Ursus arctos).

Understanding mortality causes is important for the conservation of endangered species, especially in small and isolated populations inhabiting anthropized landscapes where both natural and human-caused mortality may hinder the conservation of these species. We investigated the mortality causes of 53 free-ranging brown bears (Ursus arctos) found dead between 1998 and 2023 in the Cantabrian Mountains (northwestern Spain), a highly human-modified region where bears are currently recovering after being critically threatened in the last century. We detected natural traumatic injuries in 52.63% and infectious diseases in 39.47% of the 38 bears for which the mortality causes were registered, with 21.05% of these cases presenting signs of both infectious diseases and traumas. More specifically, almost 30% of the bears died during or after intraspecific fights, including sexually selected infanticide (10.53%). In addition, primary infectious diseases such as infectious canine hepatitis, distemper, clostridiosis and colibacillosis caused the death of 15.79% of the bears. The number of direct human-caused deaths (i.e., shooting, poisoning, snare) decreased over the study period. This study also reveals three new mortality causes triggered by pathogens, two of which-Clostridium novyi and verotoxigenic Escherichia coli-not previously described in ursids, and the other one, canine distemper virus, never reported in brown bears as cause of death. New management strategies for the conservation of Cantabrian bears, which are urgently needed due to the rapid expansion of the population, should consider the mortality causes described in this study and must promote further research to elucidate how the high prevalence of infectious diseases may threaten the current recovery of the population.

Mortality Causes in Captive Cantabrian capercaillie (Tetrao urogallus cantabricus) in Spain.

The Cantabrian capercaillie (Tetrao urogallus cantabricus) is one of the most severely threatened subspecies of capercaillie. Its current population range is restricted to a small area of the Cantabrian Mountains (northwestern Spain), with only around 200 individuals remaining. As part of the national strategy for the conservation of the subspecies, the Cantabrian capercaillie Captive Breeding Center of Sobrescobio opened in 2009. Here, we use the information provided by the necropsies performed in this facility on 29 individuals (11 males, 13 females and 5 undetermined; 16 chicks and 13 adults) in order to describe the main mortality causes of captive-bred Cantabrian capercaillies. After necropsy, tissue samples were taken for evaluation using standard methods in histology and microbiology. The majority of the captive animals (18/29, 62.07%) died due to infectious diseases, mainly due to Escherichia coli, Clostridium perfringens, or Aspergillus fumigatus infection. The remaining 11 animals died due to stress-related processes (i.e., rupture of the heart apex and cardiomyopathy or neurogenic shock) (8/29, 27.59%), duodenal obstruction and coelomitis (1/29, 3.45%), perforation of the proventriculus and heart with a briar branch (1/29, 3.45%) or euthanasia due to a valgus leg deformity that prevented proper animal welfare (1/29, 3.45%). Young animals (i.e., younger than 2 months) died mainly due to infectious diseases (14/16, 87.5%), while stress-related causes were responsible for most adult deaths (7/13, 53.85%). We additionally report that two free-ranging adult males died due to exertional myopathy. This study provides relevant information for reducing mortality in captive capercaillies and improving both living conditions in captivity and the adaptation of these animals to the wild.

Congruence between the prioritisation of conservation problems at the local and national scale: an evaluation by environmental scientists in Poland.

The anthropogenic pressure on the environment depends on the spatial scale. It is crucial to prioritise conservation actions at different spatial scales to be cost-efficient. Using horizon scanning with the Delphi technique, we asked what the most important conservation problems are in Poland at local and national scales. Twenty-six participants, PhD students, individually identified conservation issues important at the local and national scales. Each problem was then scored and classified into broader categories during the round discussions. Text mining, cross-sectional analyses, and frequency tests were used to compare the context, importance scores, and frequency of identified problems between the two scales, respectively. A total of 115 problems were identified at the local scale and 122 at the national scale. Among them, 30 problems were identical for both scales. Importance scores were higher for national than local problems; however, this resulted from different sets of problems identified at the two scales. Problems linked to urbanisation, education, and management were associated with the local scale. Problems related to policy, forestry, and consumerism were more frequent at the national scale. An efficient conservation policy should be built hierarchically (e.g. introducing adaptive governance), implementing solutions at a national scale with the flexibility to adjust for local differences and to address the most pressing issues.

The role of the brown bear Ursus arctos as a legitimate megafaunal seed disperser.

Megafaunal frugivores can consume large amounts of fruits whose seeds may be dispersed over long distances, thus, affecting plant regeneration processes and ecosystem functioning. We investigated the role of brown bears (Ursus arctos) as legitimate megafaunal seed dispersers. We assessed the quantity component of seed dispersal by brown bears across its entire distribution based on information about both the relative frequency of occurrence and species composition of fleshy fruits in the diet of brown bears extracted from the literature. We assessed the quality component of seed dispersal based on germination experiments for 11 fleshy-fruited plant species common in temperate and boreal regions and frequently eaten by brown bears. Across its distribution, fleshy fruits, on average, represented 24% of the bear food items and 26% of the total volume consumed. Brown bears consumed seeds from at least 101 fleshy-fruited plant species belonging to 24 families and 42 genera, of which Rubus (Rosaceae) and Vaccinium (Ericaceae) were most commonly eaten. Brown bears inhabiting Mediterranean forests relied the most on fleshy fruits and consumed the largest number of species per study area. Seeds ingested by bears germinated at higher percentages than those from whole fruits, and at similar percentages than manually depulped seeds. We conclude that brown bears are legitimate seed dispersers as they consume large quantities of seeds that remain viable after gut passage. The decline of these megafaunal frugivores may compromise seed dispersal services and plant regeneration processes.