Spatial variance-mass allometry of population density in felids from camera-trapping studies worldwide

Power laws are cornerstone relationships in ecology and evolutionary biology. The density-mass allometry (DMA), which predicts an allometric scaling of population abundance, and Taylor's law (TL), which predicts a decrease in the population abundance variation along with a decrease in population density, have enhanced our knowledge of inter- and intra-specific variation in population abundance. When combined, these two power laws led to the variance-mass allometry (VMA), which states that larger species have lower spatial variation in population density than smaller species. The VMA has been predicted through theoretical models, however few studies have investigated if this law is also supported by empirical data. Here, to formally test the VMA, we have used the population density estimates obtained through worldwide camera trapping studies for an emblematic and ecologically important carnivorous taxa, the Felidae family. Our results showed that the VMA law hold in felids, as well as the TL and the DMA laws; bigger cat species showed less variation for the population density than smaller species. These results have important implications for the conservation of wildlife population and confirm the validity of important ecological concepts, like the allometric scaling of population growth rate and the slow-fast continuum of life history strategies

Habitat fragmentation and anthropogenic factors affect wildcat Felis silvestris silvestris occupancy and detectability on Mt Etna

International audienceKnowledge of patterns of occupancy is crucial for planning sound biological management and for identifying areas which require paramount conservation attention. The European wildcat Felis silvestris is an elusive carnivore and is classified as ‘least concern' on the IUCN red list, but with a decreasing population trend in some areas. Sicily hosts a peculiar wildcat population, which deserves conservation and management actions, due to its isolation from the mainland. Patterns of occupancy for wildcats are unknown in Italy, and especially in Sicily. We aimed to identify which ecological drivers determined wildcat occurrence on Mt Etna and to provide conservation actions to promote the wildcats’ long-term survival in this peculiar environment. The genetic identity of the wildcat population was confirmed through a scat-collection which detected 22 different wildcat individuals. We analysed wildcat detections collected by 91 cameras using an occupancy frame work to assess which covariates influenced the detection (p) and the occupancy (ψ) estimates. We recorded 70 detections of the target species from 38 cameras within 3377 trap-days. Wildcat detection was positively influenced by the distance to the major paved roads and negatively affected by the presence of humans. Wildcat occupancy was positively associated with mixed forest and negatively influenced by pine forest, fragmentation of mixed forest and altitude. A spatially explicit predicted occupancy map, validated using an independent dataset of wildcat presence records, showed that higher occupancy estimates were scattered, mainly located on the north face and at lower altitude. Habitat fragmentation has been claimed as a significant threat for the wildcat and this is the first study that has ascertained this as a limiting factor for wildcat occurrence. Conservation actions should promote interconnectivity between areas with high predicted wildcat occupancy while minimising the loss of habitat

Prognostic factors of lung cancer in lymphoma survivors (the LuCiLyS study)

Background Second cancer is the leading cause of death in lymphoma survivors, with lung cancer representing the most common solid tumor. Limited information exists about the treatment and prognosis of second lung cancer following lymphoma. Herein, we evaluated the outcome and prognostic factors of Lung Cancer in Lymphoma Survivors (the LuCiLyS study) to improve the patient selection for lung cancer treatment. Methods This is a retrospective multicentre study including consecutive patients treated for lymphoma disease that subsequently developed non-small cell lung cancer (NSCLC). Data regarding lymphoma including age, symptoms, histology, disease stage, treatment received and lymphoma status at the time of lung cancer diagnosis, and data on lung carcinoma as age, smoking history, latency from lymphoma, symptoms, histology, disease stage, treatment received, and survival were evaluated to identify the significant prognostic factors for overall survival. Results Our study population included 164 patients, 145 of which underwent lung cancer resection. The median overall survival was 63 (range, 58–85) months, and the 5-year survival rate 54%. At univariable analysis no-active lymphoma (HR: 2.19; P=0.0152); early lymphoma stage (HR: 1.95; P=0.01); adenocarcinoma histology (HR: 0.59; P=0.0421); early lung cancer stage (HR: 3.18; P<0.0001); incidental diagnosis of lung cancer (HR: 1.71; P<0.0001); and lung cancer resection (HR: 2.79; P<0.0001) were favorable prognostic factors. At multivariable analysis, no-active lymphoma (HR: 2.68; P=0.004); early lung cancer stage (HR: 2.37; P<0.0001); incidental diagnosis of lung cancer (HR: 2.00; P<0.0001); and lung cancer resection (HR: 2.07; P<0.0001) remained favorable prognostic factors. Patients with non-active lymphoma (n=146) versus those with active lymphoma (n=18) at lung cancer diagnosis presented better median survival (64 vs. 37 months; HR: 2.4; P=0.02), but median lung cancer specific survival showed no significant difference (27 vs. 19 months; HR: 0.3; P=0.17). Conclusions The presence and/or a history of lymphoma should not be a contraindication to resection of lung cancer. Inclusion of lymphoma survivors in a lung cancer-screening program may lead to early detection of lung cancer, and improve the survival

Agriculture intensity and landscape configuration influence the spatial use of wildcats across Europe

Land use intensification is increasing worldwide and affects wildlife movements, particularly of specialist carnivores. Resource availability and anthropogenic activities drive the extent and shape of home range size. Wildlife may respond to decreased resource availability under intensification scenarios by increasing their home ranges; however they may be less affected when inhabiting sustainable agricultural landscapes. We investigate whether agricultural practices and landscape configuration influence the spatial behaviour of wildcats, a medium-sized specialist carnivore inhabiting landscapes with different degrees of agricultural presence across Europe. We focus on the effect of the proportions of high impact and low impact agriculture, forest integrity and forest edge density on wildcat home range size. We found that wildcat home range increased along with the proportion of high impact agriculture and the forest integrity, whereas it decreased when forest edge density increased. Forest edge density buffered the detrimental effects caused by high impact agriculture. To enhance the long term conservation of wildcats in Europe it is crucial to protect the sustainable mosaic-structured landscapes and prevent its conversion to homogenous intensified agricultural landscapes.HRV is beneficiary of a PhD scholarship “Severo Ochoa” from the Regional Government of Principality of Asturias. JVLB was supported by a Ramón y Cajal research contract (RYC-2015-18932) from the Spanish Ministry of Economy, Industry and Competitiveness. F. Díaz-Ruiz was supported by a postdoctoral contract from the University of Málaga (I Plan Propio de Investigación y Transferencia, call 2020).Peer reviewe

Genetic integrity of European wildcats: Variation across biomes mandates geographically tailored conservation strategies

Hybridisation between domestic and wild taxa can pose severe threats to wildlife conservation, and human-induced hybridisation, often linked to species' introductions and habitat degradation, may promote reproductive opportunities between species for which natural interbreeding would be highly unlikely. Using a biome-specific approach, we examine the effects of a suite of ecological drivers on the European wildcat's genetic integrity, while assessing the role played by protected areas in this process. We used genotype data from 1217 putative European wildcat samples from 13 European countries to assess the effects of landcover, disturbance and legal landscape protection on the European wildcat's genetic integrity across European biomes, through generalised linear models within a Bayesian framework. Overall, we found European wildcats to have genetic integrity levels above the wildcat-hybrid threshold (ca. 83%; threshold = 80%). However, Mediterranean and Temperate Insular biomes (i.e., Scotland) revealed lower levels, with 74% and 46% expected genetic integrity, respectively. We found that different drivers shape the level of genetic introgression across biomes, although forest integrity seems to be a common factor promoting European wildcat genetic integrity. Wildcat genetic integrity remains high, regardless of landscape legal protection, in biomes where populations appear to be healthy and show recent local range expansions. However, in biomes more susceptible to hybridisation, even protected areas show limited effectiveness in mitigating this threat. In the face of the detected patterns, we recommend that species conservation and management plans should be biome- and landscape-context-specific to ensure effective wildcat conservation, especially in the Mediterranean and Temperate Insular biomes.Thanks are due to FCT/MCTES for the financial support to cE3c (UIDB/00329/2020), through national funds, and the co-funding by the FEDER, within the PT2020 Partnership Agreement and Compete 2020. PM was supported by UID/BIA/50027/2021 with funding from FCT/MCTES through national funds. FDR was supported by a postdoctoral contract from the University of Málaga (I Plan Propio de Investigación y Transferencia, call 2020). This study was partly funded by research projects CGL2009-10741, funded by the Spanish Ministry of Science and Innovation and EU-FEDER, and OAPN 352/2011, funded by the Organismo Autónomo Parques Nacionales (Spain). Luxembourg sample collection has been co-funded by the Ministry of Environment, Climate and Sustainable Development of Luxembourg. We would like to thank the Bavarian Forest National Park Administration for the approval and support in collecting samples.Peer reviewe

Survival and cause-specific mortality of European wildcat (Felis silvestris) across Europe

Humans have transformed most landscapes across the globe, forcing other species to adapt in order to persist in increasingly anthropogenic landscapes. Wide-ranging solitary species, such as wild felids, struggle particularly in such landscapes. Conservation planning and management for their long-term persistence critically depends on understanding what determine survival and what are the main mortality risks. We carried out the first study on annual survival and cause-specific mortality of the European wildcat with a large and unique dataset of 211 tracked individuals from 22 study areas across Europe. Furthermore, we tested the effect of environmental and human disturbance variables on the survival probability. Our results show that mortalities were mainly human-caused, with roadkill and poaching representing 57% and 22% of the total annual mortality, respectively. The annual survival probability of wildcat was 0.92 (95% CI = 0.87–0.98) for females and 0.84 (95% CI = 0.75–0.94) for males. Road density strongly impacted wildcat annual survival, whereby an increase in the road density of motorways and primary roads by 1 km/km2 in wildcat home-ranges increased mortality risk ninefold. Low-traffic roads, such as secondary and tertiary roads, did not significantly affect wildcat's annual survival. Our results deliver key input parameters for population viability analyses, provide planning-relevant information to maintain subcritical road densities in key wildcat habitats, and identify conditions under which wildcat-proof fences and wildlife crossing structures should be installed to decrease wildcat mortality.This research was funded by: the German Federal Ministry of Transport and Digital Infrastructure (BMVI) as part of the mFund project “WilDa—Dynamic Wildlife–Vehicle Collision warning, using heterogeneous traffic, accident and environmental data as well as big data concepts” grant number 19F2014B; the Deutscher Akademischer Austauschdienst (DAAD) Research Grants, Short-Term Grants, 2020 (57507441); the Deutsche Wildtier Stiftung (DeWiSt). The data from Cabañeros National Park were collected in the frame of the project OAPN 352/2011 funded by Organismo Autónomo Parques Nacionales. MM was supported by a research contract Ramón y Cajal from the MINECO (RYC-2015-19231). FDR was supported by a postdoctoral contract funded by the University of Málaga through the grants program “Ayudas para la Incorporación de Doctores del I Plan Propio de Investigación de la Universidad de Málaga (Call 2019)”. PM was supported by UIDB/50027/2020 with funding from FCT/MCTES through national funds.Peer reviewe

Camera-trapping provides insights into adult sex ratio variability in felids

Adult sex ratio (ASR) plays a pivotal role in many ecological processes, such as population dynamics in time and space, extinction risk and reproductive success, but few patterns in the variability in ASR have been found across species. Due to the socio-spatial structure and polygynous mating system found in felids, ASR is expected to be female-biased in felids in a finite area; however, ASR is also commonly found to be either balanced or male-biased in this taxonomic group. Therefore, investigating ecological correlates of the pattern of ASR variability in felids is of prime importance both for a better understanding of evolutionary ecology and for a more evidence-based conservation of these threatened taxa. The aim of this review was to investigate whether the expected female-biased ASR occurs in felids, and whether ASR is influenced by the size of the study area, the species' body mass and the population density, taking into account the species-specific home-range requirements. We reviewed the camera-trapping literature on felids to build a large global multi-species data set on ASR variation. We used general linear mixed models to investigate ecological correlates of ASR. In small study areas, the ASR was balanced for all species, but in large areas the ASR was female-biased for large and medium cats and male-biased for small cats; sampling designs that are unsuitable for small cats (due to gaps' within the trapping grid) might explain this latter finding. Moreover, in large study areas, an increase in cat density was associated with more females, whereas in small areas the reverse was true. Our study provides a scientifically sound background for management and conservation actions of these flagship-threatened taxa of carnivores, by indicating the importance of the study area on ASR in felids. Large areas can promote the recovery of large and medium cats, as more females can be hosted

Experiences obtained from camera trapping the European Wildcat in Sicily (Italy)

The wildcat is an elusive species that is threatened with extinction in many areas of its European distribution. In Sicily the wildcat lives in a wide range of habitats and this work was done on the Etna volcano. In the 2006, after an exploration of the study area, we used camera traps with the aim to obtain pictures of the wildcat. We conducted our experiment during two periods (April 11 to August 8 - September 26 to December 16) and we used an attractant only in the first period. Twelve of the eighteen trapping stations provided a total of 24 pictures of wildcats. 9 different wildcats were identified using natural-coat marking system and morphological criteria on an area of 660 ha. Our work remarks the goodness of the camera trapping in the monitoring of wildcat’s population, as it has been successfully used for many other felids in recent years

Population density estimation of the European wildcat (Felis silvestris silvestris) in Sicily using camera trapping

The wildcat is an elusive species that is threatened with extinction in many areas of its European distribution. In Sicily the wildcat lives in a wide range of habitats; this study was done on Mount Etna. Previous camera trap monitoring was conducted in 2006 (pilot study) and in 2007 (first estimation of wildcat population size by using camera trapping with capture-recapture analyses) in the same study area. In 2009 digital camera traps in pairs were used at each station with the aim of determining the density of the wildcat’s population by using capture–recapture analyses. The coat-colour and markings system was used to determine both the taxonomical status of the photographed cat and the individual identification. Two trap-lines adjacent to each other were run in two consecutive data collection periods. Camera traps worked together for 1080 trap-days and we obtained 42 pictures of wildcats from 32 events of photographic capture, from which 10 individuals (excluding four kittens) were identified. The history capture of each individual was constructed and the software CAPTURE (model heterogeneity) was used to generate an estimation of the population density (0.28 ± 0.1 wildcat/1 Km2) by using the Full Mean Maximum Distance Moved for wildcats caught more than once to calculate the effective sampled area. The wildcat’s population density on Mount Etna falls within the medium/ high range of those found throughout Europe. Recaptures of the same individual and reproductions events have been recorded across the years. Comparison with previous studies suggested that wildcat’s density in our study area might be stable

Density of wild felids in Sonora, Mexico: a comparison of spatially explicit capture-recapture methods

Estimates of population density are crucial for wild felid conservation and are commonly conducted using camera trapping. Spatially explicit capture-recapture (SCR) survey designs often use two cameras per station to photograph both flanks of a spotted felid to confirm identities. However, if the sampling grid is inadequate, and detector devices are unable to capture an animal's complete movements, density may be overestimated. Density analyses incorporating identification inputs from both flanks derived from unpaired camera stations may offer a cost-effective solution by doubling the number of stations available to researchers. During 2008, we surveyed 164 sites for jaguars, ocelots, and bobcats using unpaired camera stations (mean trap nights per camera = 32.66, inter-trap distance = 800 m) on private ranching lands in Sonora, Mexico. We obtained 15, 52, and 229 detections of jaguars, ocelots, and bobcats from 9, 35, and 87 stations, respectively. SCR density estimates (individuals/100 km(2)) derived from a maximum likelihood multi-session model and a Bayesian spatial partial identity model (SPIM) were similar: 4.61 and 1.54 (jaguar), 4.66 and 4.33 (ocelot), and 15.22 and 15.88 (bobcat), respectively. Due to insufficient recaptures of jaguars, only SPIM provided a credible estimate of jaguar density. Jaguar density was one of the lowest reported across their distribution, which was expected given Sonora's location at the periphery of the jaguar's range. However, ocelot and bobcat populations appear to be healthy in Sonora, even within unprotected ranchlands. We recommend the use of SPIM to estimate the density of spotted felids with any dataset containing few recaptures in unpaired camera surveys