1,720,989 research outputs found
Impact of Wolf on livestock in Northern Italy and prediction of predation risk
No full textMortality due to illegal killing by humans is still today one of the main risk factors for the wolf (Canis lupus) and the effective management of conflict between wolves and livestock breeding is a great concern for species conservation. We assessed the impact of wolf on livestock in an area of Northern Apennines analyzing data provided by the Provincial Administration of Piacenza and additional data directly collected through interviews to farmers during the period 2005-2012. We recorded : i) the number of farms that have suffered predation (classified by : livestock species, productive orientation, rearing method, level of surveillance and preventive methods), ii) the number of predation events and the number of preyed animals. The effects of management factors were evaluated by Likelihood Ratio (exact test with permutation) as regard the frequencies of predation and by Multifactorial Analysis of Variance as regard the average number of heads preyed upon for each event of predation. By Regression and Curve-fit Analyses we evaluated the relationships between the number of predation events and of the number of animals preyed and 21 variables characterizing the grazing areas. Then we formulated a predictive model of the predation probability,
through a forward stepwise Binary Logistic Regression Analysis with pasture characteristics as predictors. Livestock species, productive orientation, rearing and preventive methods resulted the most important factors affecting the frequency of predation events and the number of preyed animals. The average number of preyed heads per event increased during the study period and was greater for sheep than other species. The number of predation events showed significant
relationship with the pasture slope, the percentage of mixed deciduous forest, the percentage of total deciduous forest and the distance from villages. The number of preyed animals was significantly related with the pasture exposure and with the percentage of mixed deciduous forests.
In the model of predation risk entered the rearing methods, the shape index and the percentage of coniferous forest cover, both with a negative effect on the predation probability, whereas exposure
had a positive effect. 33.3% of the pastures resulted at low predation risk (Probability of predation = 0.0 - 0.3), 4.2% at medium predation risk (Probability of predation = 0.3 - 0.6), and 62.5% at high
predation risk (Probability of predation > 0.6). Overall, 64.6% of the pastures were potentially at risk of predation (Probability of predation > 0.5)
Wolf habitat suitability in an area of Northern Apennines : a multimodel approach
No full textThe Italian wolf population was near to the extinction at the beginning of the seventies of the past century, owing to indiscriminate hunting and poisoning. In 1972 the wolf was named protected species and since this moment the recolonization of the Italian Peninsula has begun, starting
from the remaining part of the range in Southern and Central Italy and reaching the Northern Apennines (N-Italy) during the eighties. This study was aimed to individuate suitable areas for wolves in the provinces of Pavia and Piacenza, that include a trait of the Apennines chain that
links the more extended wolf areas in Emilia-Romagna and Tuscany to those of Liguria and Western Alps and where wolves suffer a high mortality due to illegal killings and accidents. From August 2011 to August 2012 we searched for wolf and wild ungulate signs of presence on 25 transect (total length 168 km) covered once a season and randomly located in an 860 km2 study area. We split the study area in 4-km2 cells by a grid spaced of 2 km and in each cell we measured the variables concerning altimetry, exposure, slope, and land use. We classified the cells crossed by transects as presence cells if wolf signs were found at least in a season and absence ones if no signs were found. We formulated habitat suitability models following an approach use vs.
availability by Binary Logistic Regression Analysis (BLRA), Ecological Niche Factor Analysis (ENFA) and Maximum Entropy algorithm (MaxEnt) and by comparing presence cells with an equal number of randomly selected ones. Moreover we formulated a habitat suitability model
following an approach presence vs. absence by BLRA, using only the cells crossed by transects and comparing presence cells with absence ones. For the first approach only the environmental variables were used, while for the second we used also the abundance of wild ungulates. We
validated all the models by the K-Fold cross validation and ROC curves. The best model was that resulting from BLRA with presence vs. availability approach, and it was used to create a suitability map for the whole hill and mountainous area of the two provinces (2408 km2). Potential wolf range was 736 km2, i.e. 30.5% of available area. The suitability map can be used to the accomplishment of the actions to awaken public opinion towards the cohabitation with wolves
and to plan the methods and interventions of damage prevention to the animal husbandry, so reducing the conflicts between human activities and wolf presence. Moreover on the basis of the habitat suitability map a network of protected areas can be designed to improve wolf protection
and conservation policy
Range expansion and redefinition of a crop-raiding rodent associated with global warming and temperature increase
No full textSince the 1970s, the crested porcupine Hystrix cristata has shown a marked range expansion in Italy. A web page has been created to collect occurrences of this species to monitor its distribution redefinition. Thus, aims of this work were (i) to identify the main predictors promoting the distribution of this large rodent in Italy and (ii) to predict its potential expansion under future climate change scenarios. A total of 1674 locations were used for this analysis, i.e., all those collected through the web page, with the exception of recently introduced populations (Sardinia, Western Liguria and Province of Varese). The current distribution of the crested porcupine covers a total of 135,177 km2, as estimated through ensemble predictions. Future climate change scenarios for 2050 and 2070 show that a further range expansion by this species would occur up to 225,576 km2, mainly towards areas where the species was historically absent. The increase of isothermality (i.e., the ratio between the mean diurnal and the annual temperature range) and the mean temperature of the driest months would help crested porcupines to reach high altitudes, e.g., in the Alps. In mountain habitats, the ongoing global warming is shifting the distribution of European forests to high elevations, thus potentially providing porcupines with suitable habitats. A reduction in snow cover and the snow period at ground level would remove an important barrier to the range expansion of the crested porcupine in Italy, and thus facilitate digging and food search by this large rodent. Despite being protected at national and international levels, the crested porcupine is reported to be an introduced species to Italy and, therefore, monitoring its range expansion is required. Furthermore, there are complaints about crop damage in agriculture ecosystems, and the species is still widely poached, thus additional management practices are required. Thus, given the conservation interest of this large rodent, an integrated and constantly updated monitoring system that sustains an addressed set of decision-making tools is recommended
Modeling a Red deer population reintroduced in an area of Northern Apennines (N-Italy)
No full textAt the beginning of the past Century only two remnant populations of red deer (Cervus elaphus) were present in Italy : one in the Eastern Alps (Monastero and Venosta valleys) and the other in the Po Plain near the coast of Adriatic Sea (Mesola Forest). The present Alpine population was originated by immigration from Switzerland, Austria, and Slovenia (Central and Eastern Alps) and by reintroductions (Western Alps), whereas in the Apennines red deer was reintroduced since 1960-70. At present Apennine populations are fragmented and isolated even if an increasing trend of density and occupied range was recorded. We monitored from 2002 to 2012 a protected population of red deer reintroduced in late eighties in the hilly and mountainous areas of the Piacenza province (Northern Apennines), in order to detect changes
of population size and range, and to formulate a model of habitat suitability for the prediction of future expansion of population. We carried out counts of roaring males in September of each year and collected systematic observations all year round to define population structure and
reproductive success. We used species locations, to define yearly ranges and core areas by Kernel Analyses (KA) at 99% and 50%, curve fit regression to detect trend of the population and its range, and Ecological Niche Factor Analysis (ENFA) to model habitat suitability and potential range. For ENFA we subdivided the study area in 4-km2 cells and in each cell we measured the altimetry, exposure, slope, and land use variables; the cells where at least one observation was collected in the study period were considered as presence ones. Finally we carried out Population Viability Analyses (PVA) to predict population trend and to explore the
harvesting possibility. Deer population showed a slow increasing trend (from 4 roaring males in 2002 to 70 in 2012). Only KA50% resulted in a low increasing trend (F=13.78; df=1; P=0.014; R2=0.73). ENFA showed a global marginality of 0.53 and a tolerance of 0.71. The main variables positively related to the marginality were broad-leaved and conifer forests, pastures, East aspect, altitudes from 1000 to 1800 m a.s.l., and slopes between 10° and 30°. The model provided a habitat suitability map that defined a potential red deer range of 580 km2 (22.4% of the Piacenza province). K-Fold cross validation and ROC curves showed a high predictive power of the model (Rho=0. 96; P<0.0001; AUC=0.99; P<0.0001). PVAs showed an increasing trend of the population without harvest from 300 to 900 individuals in 30 years (survival probability=1), an increase with a harvest equal to 5% (from 300 to 825 individuals;
survival probability=0.99), and a stability but with a low survival probability (0.63) with a harvest equal to10%. Red deer is an important big game species and it has a high conservation value being a selected prey by wolves; however if populations reach high densities they can
have a heavy impact on agriculture causing damages in particular on vineyards and orchards. Consequently it is important to maintain populations at sustainable densities by a slight harvesting
Noninvasive sampling and genetic variability, pack structure, and dynamics in an expanding wolf population
No full textAfter centuries of population decline and range contraction, gray wolves (Canis lupus) are now expanding in Europe. Understanding wolf social structure and population dynamics and predicting their future range expansion is mandatory to design sound conservation strategies, but field monitoring methods are difficult or exceedingly expensive. Noninvasive genetic sampling offers unique opportunities for the reliable monitoring of wolf populations. We conducted a 9-year-long monitoring program in a large area (approximately 19,171 km 2) in northern Italy, aiming to identify individuals, estimate kinship, reconstruct packs, and describe their dynamics. Of 5,065 biological samples (99% scats), we genotyped and sexed 44% reliably using 12 unlinked autosomal microsatellites, 4 Y-linked microsatellites, and a diagnostic mitochondrial DNA control-region sequence. We identified 414 wolves, 88 dogs, and 16 wolf × dog hybrids. Wolves in the study area belonged to at least 42 packs. We reconstructed the genealogy of 26 packs. The mean pack size was 5.6 ± 2.4 SD, including adoptees, with a mean minimum pack home range of 74 km2 ± 52 SD. We detected turnovers of breeding pairs in 19% of the packs. Reproductive wolves were unrelated and unrelated dispersers founded new packs, except for 1 pack founded by a brother-sister pair. We did not detect multiple breeding females in any packs. Overall, the population was not inbred. We found significant isolation by distance and spatial autocorrelation, with nonrandom genetic structure up to a distance of approximately 17 km. We detected 37 dispersers, 14 of which became breeders in new or already existing packs. Our results can be used to model habitat use by wolves, to estimate survival rates, to predict future expansion of the wolf population, and to build risk maps of wolf-human conflicts. © 2014 American Society of Mammalogists
Selection of wild ungulates by wolves Canis lupus (L. 1758) in an area of the Northern Apennines (North Italy)
No full textWe investigated the patterns of wild ungulate selection by wolves in an 860 km 2 study area of the Northern Apennines (North Italy), in order to detect seasonal variation in wolf diet and changes of feeding habits in relation to the increased abundance of wild ungulates. From June 2007 to May 2008 we collected wolf scats and recorded the signs of presence of wild ungulate species along 25 transects, representative of the different habitat types within the study area. We analysed the scats to identify the main food items used by wolves in each season and we compared the proportions of biomass of wild ungulate species in the diet (use) to those calculated from the signs of presence (availability). We recorded significant seasonal changes in wolf feeding habits, but the main food items were wild ungulates, mainly wild boars, and medium-sized mammals. Livestock (sheep, goats, and calves) were used only in summer and early autumn, during the grazing period, in small quantities. Comparing the current diet of wolves to that recorded in the past in the same study area highlighted significant differences for wild ungulates and livestock, the former being more used nowadays and the latter less. Our study showed that, in the Northern Apennines, the feeding behaviour of wolves has evolved towards a greater use of wild prey, so reducing the impact on livestock and consequently wolf-human conflicts. Moreover, predation by wolves was directed towards the most abundant species of wild ungulates. © 2012 Copyright 2011 Dipartimento di Biologia Evoluzionistica dell'Università, Firenze, Italia
Combining climate, land use change and dispersal to predict the distribution of endangered species with limited vagility
Full text linkAim Many rare species are dispersal-limited; their colonization capacity can be impacted by land use and climate changes. Most ecological niche models predict the distribution of species under future climate and land use change scenarios without incorporating species-specific dispersal abilities. Here we investigate the effect of climate and land use change on low vagile species accounting for their dispersal capacity and define accessible areas in the future.Location Europe.Taxon Saproxylic beetles.Methods We used the current (2007-2012) occurrences of six endangered saproxylics to develop ecological niche models using current climate and land use conditions. We projected species distributions under four future climate and land use change scenarios to estimate their potential occurrences. Finally, accounting for species-specific dispersal, we limited their distributions to accessible areas in 2040-2050.Results Without accounting for dispersal abilities we found a strong and positive impact of climate change on the distribution of Cerambix cerdo, Cucujus cinnaberinus, Morimus funereus and Rosalia alpina and a positive effect of land use change on the distribution of Lucanus cervus and Osmoderma eremita. When species-specific dispersal was included, we found a strong and positive impact of land use change on the distribution of all the species. In this case climate change had a lower but positive effect on the distribution of C. cerdo, C. cinnaberinus, L. cervus and R. alpina, and a negative effect on the distribution of O. eremita.Main conclusion We found that climate change would promote the expansion of saproxylic beetles only in the unrealistic case of unlimited dispersal. Accounting for dispersal abilities, the expansion of our species would be mainly conditioned by the effect of land use change. Thus, we encourage researchers to combine climate and land use change with dispersal when projecting species distribution under future scenarios to accurately identify areas with fundamental species-specific resources
Does habitat use and ecological niche shift over the lifespan of wild species? Patterns of the bearded vulture population in the Western Alps
No full textWe analysed bearded vulture (Gypaetus barbatus) occurrences collected through long-term monitoring (from 1993 to 2010) in the Western Alps (1) to test whether ecological niches shift due to individual development and (2) to verify whether these patterns could reflect their spatial distribution. Thus, we compared the distribution patterns of three age classes ('young', 'sub-adults' and 'adults') through the K-select analysis. We then computed ten species distribution models (SDMs) and their average prediction to test for differences in age class distribution. The K-select analysis showed highly significant differences in the ecological niche among all the age classes and we also found highly significant differences in all the SDMs among the three age classes considered. Our results quantitatively showed that target species exhibits age specific shifts in the ecological niche and changes in the spatial distribution of individuals. Our methods are potentially widely applicable for testing differences among age classes of other species and thus, defining the best conservation actions (such as re-introduction) by taking into account different requirements in different stages of the individuals' life
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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