Sharing space with large carnivores on a human-dominated continent like Europe results in multiple conflictful interactions with human interests, of which depredation on livestock is the most ...widespread. We conducted an analysis of the impact by all four European large carnivores on sheep farming in 10 European countries, during the period 2010–2015. We ran a hierarchical Simultaneous Autoregressive model, to assess the influence of several ecological factors on the reported depredation levels. About 35,000 (SD = 4110) sheep kills were compensated in the ten countries as caused by large carnivores annually, representing 0.5% of the total sheep stock. Of them, 45% were recognized as killed by wolves, 24% by wolverines, 19% by lynx and 12% by bears. We found a positive relationship between wolf distribution and the number of compensated sheep, but not for the other three species. Depredation levels were lower in the areas where large carnivore presence has been continuous compared to areas where they disappeared and returned in the last 50 years. Our study shows that a few large carnivores can produce high damage, when the contribution of environmental, social, and economic systems predisposes for it, whereas large populations can produce a limited impact when the same components of the system reduce the probability that depredations occur. Time of coexistence plays in favour of a progressive reduction in the associated costs, provided that the responsible agencies focus their attention both on compensation and co-adaptation.
Non-invasive genetic sampling (NGS) is increasingly used to estimate the abundance of rare or elusive species such as the wolf (
Canis lupus
), which cannot be directly counted in forested mountain ...habitats. Wolf individual and familial home ranges are wide, potentially connected by long-range dispersers, and their populations are intrinsically open. Appropriate demographic estimators are needed, because the assumptions of homogeneous detection probability and demographic closeness are violated. We compiled the capture–recapture record of 418 individual wolf genotypes identified from ca. 4,900 non-invasive samples, collected in the northern Italian Apennines from January 2002 to June 2009. We analysed this dataset using novel capture–recapture multievent models for open populations that explicitly account for individual detection heterogeneity (IDH). Overall, the detection probability of the weakly detectable individuals, probably pups, juveniles and migrants (
P
= 0.08), was ca. six times lower than that of the highly detectable wolves (
P
= 0.44), probably adults and dominants. The apparent annual survival rate of weakly detectable individuals was lower (Φ = 0.66) than those of highly detectable wolves (Φ = 0.75). The population mean annual finite rate of increase was λ = 1.05 ± 0.11, and the mean annual size ranged from
N
= 117 wolves in 2003 to
N
= 233 wolves in 2007. This procedure, combining large-scale NGS and multievent IDH demographic models, provides the first estimates of abundance, multi-annual trend and survival rates for an open large wolf population in the Apennines. These results contribute to deepen our understanding of wolf population ecology and dynamics, and provide new information to implement sound long-term conservation plans.
Both evolutionary ecologists and wildlife managers make inference based on how fitness and demography vary in space. Spatial variation in survival can be difficult to assess in the wild because (1) ...multisite study designs are not well suited to populations that are continuously distributed across a large area and (2) available statistical models accounting for detectability less than 1.0 do not easily cope with geographical coordinates. Here we use penalized splines within a Bayesian state-space modeling framework to estimate and visualize survival probability in two dimensions. The approach is flexible in that no parametric form for the relationship between survival and coordinates need be specified a priori. To illustrate our method, we study a game species, the Eurasian Woodcock
Scolopax rusticola
, based on band recovery data (5000 individuals) collected over a >50 000-km
2
area in west-central France with contrasted habitats and hunting pressures. We find that spatial variation in survival probability matches an index of hunting pressure and creates a mosaic of population sources and sinks. Such analyses could provide guidance concerning the spatial management of hunting intensity or could be used to identify pathways of spatial variation in fitness, for example, to study adaptation to changing landscape and climate.
1. Industrial longline fishing has been suspected to impact upon black-footed albatross populations Phoebastria nigripes by increasing mortality, but no precise estimates of bycatch mortality are ...available to ascertain this statement. We present a general framework for quantifying the relationship between albatross population and longline fishing in absence of reliable estimates of bycatch rate. 2. We analysed capture-recapture data of a population of black-footed albatross to obtain estimates of survival probability for this population using several alternative models to adequately take into account heterogeneity in the recapture process. Instead of trying to estimate the number of birds killed by using various extrapolations and unchecked assumptions, we investigate the potential relationship between annual adult survival and several measures of fishing effort. Although we considered a large number of covariates, we used principal component analysis to generate a few uncorrelated synthetic variables from the set and thus we maintained both power and robustness. 3. The average survival for 1997-2002 was 92%, a low value compared to estimates available for other albatross species. We found that one of the synthetic variables used to summarize industrial longline fishing significantly explained more than 40% of the variation in adult survival over 11 years, suggesting an impact by longline fishing on albatross' survival. 4. Our analysis provides some evidence of non-linear variation in survival with fishing effort. This could indicate that below a certain level of fishing effort, deaths due to incidental catch can be partially or totally compensated for by a decrease in natural mortality. Another possible explanation is the existence of a strong interspecific competition for accessing the baits, reducing the risk of being accidentally hooked. 5. Synthesis and applications. The suspicion of a significant impact of longline fishing on the black-footed albatross population was supported by the combination of a low estimate of adult survival for the study period, and a significant relationship between adult survival and a synthetic measure of fishing effort. This study highlights the sensitivity of the black-footed albatross to commercial longline fishing, and should exhort fishery management authorities to find adequate seabirds avoidance methods and to encourage their employment.
Great apes are threatened with extinction, but precise information about the distribution and size of most populations is currently lacking. We conducted orangutan nest counts in the Malaysian state ...of Sabah (North Borneo), using a combination of ground and helicopter surveys, and provided a way to estimate the current distribution and size of the populations living throughout the entire state. We show that the number of nests detected during aerial surveys is directly related to the estimated true animal density and that a helicopter is an efficient tool to provide robust estimates of orangutan numbers. Our results reveal that with a total estimated population size of about 11,000 individuals, Sabah is one of the main strongholds for orangutans in North Borneo. More than 60% of orangutans living in the state occur outside protected areas, in production forests that have been through several rounds of logging extraction and are still exploited for timber. The role of exploited forests clearly merits further investigation for orangutan conservation in Sabah.
Abstract Understanding how populations respond to variability in environmental conditions and interspecific interactions is one of the biggest challenges of population ecology, particularly in the ...context of global change. Although many studies have investigated population responses to climate change, very few have explicitly integrated interspecific relationships when studying these responses. In this study, we aimed to understand the combined effects of interspecific interactions and environmental conditions on the demographic parameters of a prey–predator system of three sympatric seabird populations breeding in Antarctica: the south polar skua ( Catharacta maccormicki ) and its two main preys during the breeding season, the Adélie penguin ( Pygoscelis adeliae ) and the emperor penguin ( Aptenodytes forsteri ). We built a two‐species integrated population model (IPM) with 31 years of capture–recapture and count data and provided a framework that made it possible to estimate the demographic parameters and abundance of a predator–prey system in a context where capture–recapture data were not available for one species. Our results showed that predator–prey interactions and local environmental conditions differentially affected south polar skuas depending on their breeding state of the previous year. Concerning prey–predator relationships, the number of Adélie penguin breeding pairs showed a positive effect on south polar skua survival and breeding probability, and the number of emperor penguin dead chicks showed a positive effect on the breeding success of south polar skuas. In contrast, there was no evidence for an effect of the number of south polar skuas on the demography of Adélie penguins. We also found an important impact of sea ice conditions on both the dynamics of south polar skuas and Adélie penguins. Our results suggest that this prey–predator system is mostly driven by bottom‐up processes and local environmental conditions.
•An integrated predator–prey model is designed using a nonlinear MPM framework.•It combines capture–recapture, reproduction and count data into a single model.•The data combination allows to estimate ...interactions when count-only data cannot.•We compare the efficiency of several data availability scenarios.•Reproduction data substantially improve model estimation at little cost.
Inferring interactions between populations of different species is a challenging statistical endeavour, which requires a large amount of data. There is therefore some incentive to combine all available sources of data into a single analysis to do so. In demography and single-population studies, Integrated Population Models combine population counts, capture–recapture and reproduction data to fit matrix population models. Here, we extend this approach to the community level in a stage-structured predator–prey context. We develop Integrated Community Models (ICMs), implemented in a Bayesian framework, to fit multispecies nonlinear matrix models to multiple data sources. We assessed the value of the different sources of data using simulations of ICMs under different scenarios contrasting data availability. We found that combining all data types (capture–recapture, counts, and reproduction) allows the estimation of both demographic and interaction parameters, unlike count-only data which typically generate high bias and low precision in interaction parameter estimates for short time series. Moreover, reproduction surveys informed the estimation of interactions particularly well when compared to capture–recapture programs, and have the advantage of being less costly. Overall, ICMs offer an accurate representation of stage structure in community dynamics, and foster the development of efficient observational study designs to monitor communities in the field.
Estimating eco-epidemiological parameters in free-ranging populations can be challenging. As known individuals may be undetected during a field session, or their health status uncertain, the ...collected data are typically "imperfect". Multi-event capture-mark-recapture (MECMR) models constitute a substantial methodological advance by accounting for such imperfect data. In these models, animals can be "undetected" or "detected" at each time step. Detected animals can be assigned an infection state, such as "susceptible" (S), "infected" (I), or "recovered" (R), or an "unknown" (U) state, when for instance no biological sample could be collected. There may be heterogeneity in the assignment of infection states, depending on the manifestation of the disease in the host or the diagnostic method. For example, if obtaining the samples needed to prove viral infection in a detected animal is difficult, this can result in a low chance of assigning the I state. Currently, it is unknown how much uncertainty MECMR models can tolerate to provide reliable estimates of eco-epidemiological parameters and whether these parameters are sensitive to heterogeneity in the assignment of infection states. We used simulations to assess how estimates of the survival probability of individuals in different infection states and the probabilities of infection and recovery responded to (1) increasing infection state uncertainty (i.e., the proportion of U) from 20 to 90%, and (2) heterogeneity in the probability of assigning infection states. We simulated data, mimicking a highly virulent disease, and used SIR-MECMR models to quantify bias and precision. For most parameter estimates, bias increased and precision decreased gradually with state uncertainty. The probabilities of survival of I and R individuals and of detection of R individuals were very robust to increasing state uncertainty. In contrast, the probabilities of survival and detection of S individuals, and the infection and recovery probabilities showed high biases and low precisions when state uncertainty was >50%, particularly when the assignment of the S state was reduced. Considering this specific disease scenario, SIR-MECMR models are globally robust to state uncertainty and heterogeneity in state assignment, but the previously mentioned parameter estimates should be carefully interpreted if the proportion of U is high.
We assessed spatial and temporal variation in reporting probability of banded Greater Snow Geese (Chen caerulescens atlantica) shot by hunters in eastern North America and evaluated potential ...residual biases in kill rate estimation. Adult Greater Snow Geese were marked with reward (value: US$10, $20, $30, $50, and $100) and standard bands ($0, control) in the Canadian Arctic from 2003 to 2005. We used a spatially explicit multinomial model based on 200 direct recoveries from 4256 banded geese to estimate reporting rate and harvest rate. We found that reporting rate for standard bands varied over time whereas harvest rate was higher in Canada than in the U.S. The reporting probability increased from 0.40 + or - 0.11 in the first year of the study to 0.82 + or - 0.14 and 0.84 + or - 0.13 the second and third years, respectively. Overall, these reporting rates are higher than two previous estimates for this population, which leads to lower estimates of kill rate. However, the large annual differences in reporting rates found in this study lead to uncertainty in the estimation of kill rate. We suggest that the increase in reporting rate in the last two year of the study may be due to the dissemination of information among hunters regarding the presence of reward bands on birds, resulting in increased reporting rate for all bands. This raises issues about the need to adequately inform the public in such large-scale studies to avoid undesirable temporal trends over the course of the study.Original Abstract: Nous avons determine la variabilite spatiale et temporelle de la probabilite de retourner des bagues de Grandes Oies des neiges (Chen caerulescens atlantica) recoltees par les chasseurs dans l'Est de l'Amerique du Nord, et evalue les biais inherents potentiels dans l'estimation du taux de recolte. Les oies adultes ont ete marquees a l'aide de bagues recompense (d'une valeur de 10, 20, 30, 50 ou 100 $ US) et standards (0 $ US, temoin) dans l'Arctique canadien de 2003 a 2005. Afin d'estimer le taux de retour de bagues par les chasseurs et le taux de recolte, nous avons utilise un modele multinomial spatialement explicite fonde sur 200 recuperations directes de bagues provenant d'un ensemble de 4256 oies baguees. Nos resultats indiquent que le taux de retour par les chasseurs pour les bagues standards a varie au cours du temps, tandis que le taux de recolte etait plus eleve au Canada qu'aux Etats-Unis. La probabilite de retour de bagues par les chasseurs a augmente de 0,40 + or - 0,11 la premiere annee de l'etude a 0,82 + or - 0,14 et 0,84 + or - 0,13 les deuxieme et troisieme annees, respectivement. Ces taux de retour de bagues sont superieurs a ceux estimes precedemment pour cette population, entrainant des estimations du taux de recolte plus faibles. Toutefois, la forte variation interannuelle dans les taux de retour de bagues par les chasseurs observee dans la presente etude engendre une grande incertitude pour l'estimation du taux de recolte. Nous suggerons que l'augmentation du taux de retour de bagues observee au cours des deux dernieres annees de notre etude pourrait etre attribuable a la dissemination de l'information au sein des chasseurs quant a l'existence de bagues recompense sur les oiseaux, conduisant ainsi a une augmentation du taux de retour pour tout type de bagues. Cette etude souligne l'importance des informations a transmettre au public lors d'etudes a grande echelle afin d'eviter des tendances temporelles indesirables au cours de celles-ci.
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