Survival among juvenile ungulates is an important demographic trait affecting population dynamics. In many systems, juvenile ungulates experience mortality from large carnivores, hunter harvest and climate-related factors. These mortality sources often shift in importance both in space and time. While wolves (Canis lupus) predate on moose (Alces alces) throughout all seasons, brown bear (Ursus arctos) predation and human harvest happen primarily during early summer and fall, respectively. Hence, understanding how the mortality of juvenile moose is affected by predation, harvest and climate is crucial to adaptively managing populations and deciding sustainable harvest rates. We used data from 39 female moose in south-central Scandinavia to investigate the mortality of 77 calves in summer/fall and winter/spring, in relation to carnivore presence (defined as wolf presence and bear density), summer productivity, secondary road density, winter severity and migratory strategy (migratory versus resident) using logistic regressions. Summer mortality varied significantly between years but was not correlated to any of our covariates. In winter, calf mortality was higher with deeper snow in areas with wolves compared to areas without and increased more strongly with an increasing proportion of clearcuts/young forests in the presence of wolves compared to when wolves were absent. Lastly, increasing hunting risk was associated with higher calf mortality, and migratory females had higher calf mortality compared to stationary ones. Our study provides useful insight into mortality rates of moose calves coexisting with two large carnivores and with an intensive harvest pressure. Increasing our understanding of the mechanisms driving calf mortality both in summer and winter will become increasingly important if the populations of wolves and bears continue to expand and the moose population declines, and both summers and winters become warmer.
Chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is a major driver of amphibian decline worldwide. The global presence of Bd is driven by a synergy of factors, such as climate, species life history, and amphibian host susceptibility. Here, using a Bayesian data-mining approach, we modelled the epidemiological landscape of Bd to evaluate how the infection varies across several spatial, ecological, and phylogenetic scales. We compiled global information on Bd occurrence, climate, species ranges, and phylogenetic diversity to infer the potential distribution and prevalence of Bd. By calculating the degree of co-distribution between Bd and our set of environmental and biological variables (e.g., climate and species), we identified which factors could potentially be related to Bd presence and prevalence using a geographic correlation metric, epsilon (ε). We fitted five ecological models based on: i) amphibian species identity, ii) phylogenetic species variability values for a given species assemblage, iii) temperature, iv) precipitation, and v) all variables together. Our results extend the findings of previous studies by identifying the epidemiological landscape features of the presence of Bd. This ecological modelling framework allowed us to generate explicit spatial predictions for Bd prevalence at global scale and a ranked list of species with high/low probability of Bd presence. Our geographic model was able to identify areas with high potential for Bd prevalence as potential risk areas and areas with low potential Bd prevalence as potential refuges (free Bd). At the amphibian assemblage level, we found a non-relationship with amphibian phylogenetic signals, but a significantly negative correlation between observed species richness and Bd prevalence indicated a potential dilution effect at the landscape scale. Our model may identify potential susceptible species and areas at risk of Bd presence which could be used to prioritize regions for amphibian conservation efforts and assess species and assemblage risk
Monitoring population dynamics is of fundamental importance in conservation but assessing trends in abundance can be costly, especially in large and rough areas. Obtaining trend estimations from counts performed in only a portion of the total area (sample counts) can be a cost-effective method to improve the monitoring and conservation of species difficult to count. We tested the effectiveness of sample counts in monitoring population trends of wild animals, using as a model population the Alpine ibex (Capra ibex) in Gran Paradiso National Park (Italy), both with computer simulations and using historical census data collected over the last 65 years. Despite sample counts could fail to correctly estimate the true population abundance, sampling half of the target area could reliably monitor the trend of the target population. In case of strong changes in abundance, an even lower proportion of the total area could be sufficient to identify the direction of the population trend. However, when there is a high yearly trend variability, the required number of samples increases and even counting in the entire area can be ineffective to monitor population dynamics. Lastly, the effect of other parameters (such as which portion of the area is sampled or the detectability) was marginal, but these should be tested case by case. Sample counts could therefore constitute a viable alternative to assess population trends, allowing for important, cost-effective improvements in the monitoring of wild animals of conservation interest.
A study aimed at assessing the structure of rodent and shrew assemblages inhabiting a degradation gradient while considering rainfall patterns, was conducted in one of few remaining lowland tropical forests in Eastern Africa. We collected a unique dataset of rodents and shrews, representing 24 species (19 rodents, 5 shrews). The most abundant species alternated in dominance as species abundance significantly fluctuated across the study period following a degradation gradient (F2,33 = 5.68, p = 0.007). While only generalist species were observed near the degraded forest edge, habitat specialists such as Deomys ferrugineus, Malacomys longipes and Scutisorex congicus, were observed in the primary forest interior suggesting a significant (X2 = 1165.329, P<0.001) association between species and their associated habitats and habitat attributes. There was also an observed correlation between rainfall patterns and species abundance. Capturing more species in adjacent fallows and along the degraded forest edge suggests that many species are able to live in degraded habitats that offer a variety of food resources. The continued pressure on forest resources, however, may lead to changes in habitat structure. This, coupled with the dependence of forest ecological functions on rainfall, which is typically not the case, may ultimately cause the local extinction of highly specialized but less adaptable species.
The civil war in Côte d’Ivoire between 2002 and 2010 led to a hike in human disturbances and the disappearance of African lions (Panthera leo) from the Comoé National Park (CNP). After the crisis, many efforts to conserve and restore this ecosystem and its biodiversity have been made and the management authority is considering the reintroduction of lions. We assessed the acceptance of the reintroduction of the lions by the local populations; through a sociological survey, we administered questionnaires to 307 people in 23 villages bordering CNP. A large majority (71%, n=218) were in favor of the return of the lions, with significant variation among ethnic groups. A general linear model analysis (GLM) revealed that apart from ethnic group, profession and origin (village) are significantly determinant for the acceptance of lion reintroduction to CNP. Most respondents had knowledge of the species (96%, n=296). The majority of respondents (81%, n=250) acknowledged having coexisted with lions, with previous conflicts with lions reported by 16% (n = 49) of respondents and a willingness to coexist with future lions reported by 81% (n = 248) of respondents. More than 84% (n=260) of respondents believed that there would be benefits associated with lion return to CNP and 52% (n=161) and 14% (n=44) of respondents believed that the potential benefits would be greater and less than the possible risks associated with lion return. Just under half of respondents (42%; n=129) confirmed the current participatory management of CNP while the majority (91%; n=280) confirmed the possibility of taking own precautions to prevent attacks from future lion. We recommend the improvement of the involvement of indigenous communities in any reintroduction and the implementation of environmental education projects as a condition for the potential reintroduction of lions.