Impact of Wolf on livestock in Northern Italy and prediction of predation risk

Mortality 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

The 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

Diet of wolves and selection of wild ungulates in an area of Northern Italy

The trophic ecology of wolves was studied in a mountainous area of the Italian Northern Apennines from 2007 to 2012. We defined the selection process of wild ungulates to highlight seasonal variations in dietary habits of the wolf in relation to prey abundance. During the study period we collected wolf scats and recorded signs of prey and competitor presence along a network of transects randomly chosen and representative of the different habitats in the area. The results of this study were expressed as frequencies of occurrence and mean percent volumes of prey species. We analysed wolf scats to identify the main food groups consumed by the predator in every season and we compared the proportions of biomass of wild ungulate species in the diet with those calculated with the signs of presence. Annual and seasonal variations in mean percent volumes of food categories and wild and domestic ungulate species were analyzed using nonparametric multivariate analysis of variance. We calculated Levins’ B index to assess wolf diet breadth; in particular, the index was calculated for every season summing up years and for every year summing up seasons. In order to assess the pattern of selection of wild ungulates we calculated the Manly a index. We observed a decrease of diet breadth in the study period, with an increasing use of wild ungulates and a decreasing consumption of livestock, depending on the increase in the availability of wild prey species. Significant seasonal variations were observed in trophic habits of the wolf, but generally there was a wide use of wild ungulates (63.6% in volume summing up years and seasons), especially >1-year-old wild boars. Livestock (20.6% in volume summing up years and seasons) was mainly taken in summer, which corresponds to the period of greater presence of domestic ungulates on pastures. The analyses of selection patterns showed that wolves use either the available prey species, exploiting each species in relation to its abundance and accessibility. Considering the four years of study, it is possible to hypothesize the existence of functional responses of wolves to changes in abundance of the main prey species. The highlighted change in wolf diet, towards a greater use of wild ungulates and a strong decrease of the impact on animal husbandry, is an important step in the process of recovery and conservation of the wolf