Situació actual de l'ós bru als Pirineus Centrals. Evolució de la població des de la reintroducció i perspectives de futur. L'ós, reintroducció sense diàleg

Una reintroducció és el restabliment d’una espècie a un territori on havia viscut en temps històrics i que havia desaparegut principalment per causes antròpiques. El projecte ‘Ós bru’ va ser un programa pilot. Aquest es va fer amb la captura, l’alliberament i el seguiment de tres exemplars d’ós bru a partir de l’any 1996. Després en va haver altres. El primer objectiu va ser estudiar i comprovar l’adaptació dels óssos a l’hàbitat dels Pirineus. El segon objectiu va ser comprovar la resposta de la població local a la presència dels óssos. Paraules clau: ós, conflicte, diàleg, Estat, administració, Espanya, Catalunya, Franç

Invasive crayfish reduce food limitation of alien American mink and increase their resilience to control

Trophic relationships between invasive species in multiply invaded ecosystems may reduce food limitation relative to more pristine ecosystems and increase resilience to control. Here, we consider whether invasive predatory American mink Neovison vison are trophically subsidized by invasive crayfish. We collated data from the literature on density and home range size of mink populations in relation to the prevalence of crayfish in the diet of mink. We then tested the hypothesis that populations of an invasive predator reach higher densities and are more resilient to lethal control when they have access to super-abundant non-native prey, even in the absence of changes in density dependence, hence compensatory capacity. We found a strong positive relationship between the proportion of crayfish in mink diet and mink population density, and a negative relationship between the proportion of crayfish in mink diet and mink home range size, with crayfish contribution to mink diet reflecting their abundance in the ecosystem. We then explored the consequence of elevated mink density by simulating a hypothetical eradication program with a constant harvest in a Ricker model. We found that mink populations were more resilient to harvest in the presence of crayfish. As a result, the simulated number of mink harvested to achieve eradication increased by 500 % in the presence of abundant crayfish if carrying capacity increased by 630 %. This led to a threefold increase in time to eradication under a constant harvest and an approximately 20-fold increase in the cumulative management cost. Our results add to evidence of inter-specific positive interactions involving invasive species, and our simple model illustrates how this increases management cost

Spatial mixing of mitochondrial lineages and greater genetic diversity in some invasive populations of the American mink (Neovison vison) compared to native populations

The genetic characteristics of introduced populations have a relevant impact on their ability to establish and spread. The American mink (Neovison vison), native to North America, is an important invasive species in the Iberian Peninsula. Here, we used mitochondrial DNA sequences data to investigate the genetic diversity and phylogeographic structure of invasive versus native populations of this species. We also evaluated whether genetic diversity in invasive populations could be explained by the genetic characteristics of the native sources from which they derived. Phylogenetic analysis revealed two major lineages in the native range, which indicated a clear separation between western and eastern populations. On the contrary, we found no evidence of genetic structure in the invasive range. This was probably the result of the diverse origins of the released specimens and the rapid expansion and encounters of the introduced populations. We detected spatial mixing of both North American lineages in several sampling localities of the north central area of the Iberian Peninsula, giving rise to high levels of genetic diversity in some areas compared to North American populations. This could potentially lead to higher fitness of these individuals and thus increase the population viability and invasiveness of this species. These results point to the need to better study the populations in which lineages mix and, if necessary, intensify control efforts in them

Dieta otoño-invernal de tres carnívoros, visón europeo (Mustela lutreola), nutria euroasiática (Lutra lutra)

This study describes the autumn-winter diet of three carnivores (Mustela lutreola, Lutra lutra and Genetta genetta) in northern Spain. Diet composition was analysed from 85 European mink, 156 otter and 564 spotted genet fecal samples The European mink diet was based on small mammals (relative frequency of occurrences 38.1%), fish (30.9%) and birds (16.7%). Spotted genet consumed mainly small mammals, birds and fruits, whilst otter predated practically only fish (95%). Using Levins’ index, trophic-niche widths in European mink, small–spotted genet and Eurasian otter were 3.76, 3.77 and 1.10, respectively. The trophic niche overlap by Pianka index for autumn-winter was 0.77 for European mink vs. Small-spotted genet, and 0.60 for European mink vs. otter. The average size of brown trout taken by otter was larger than those consumed by European mink. Key words: European mink (Mustela lutreola), Eurasian otter (Lutra lutra), Small–spotted genet (Genetta genetta), Diet, Spain.This study describes the autumn-winter diet of three carnivores (Mustela lutreola, Lutra lutra and Genetta genetta) in northern Spain. Diet composition was analysed from 85 European mink, 156 otter and 564 spotted genet fecal samples The European mink diet was based on small mammals (relative frequency of occurrences 38.1%), fish (30.9%) and birds (16.7%). Spotted genet consumed mainly small mammals, birds and fruits, whilst otter predated practically only fish (95%). Using Levins’ index, trophic-niche widths in European mink, small–spotted genet and Eurasian otter were 3.76, 3.77 and 1.10, respectively. The trophic niche overlap by Pianka index for autumn-winter was 0.77 for European mink vs. Small-spotted genet, and 0.60 for European mink vs. otter. The average size of brown trout taken by otter was larger than those consumed by European mink. Key words: European mink (Mustela lutreola), Eurasian otter (Lutra lutra), Small–spotted genet (Genetta genetta), Diet, Spain.Se describe la dieta otoño-invernal de tres carnívoros (Mustela lutreola, Lutra lutra y Genetta genetta) en el norte de España. La dieta fue analizada a partir de 85 muestras de visón europeo, 156 de nutria euroasiática y 564 de gineta común. El visón europeo basó su dieta en micromamíferos (38,1% de frecuencia relativa), peces (30,9%) y aves (16,7%). La gineta común consumió principalmente micromamíferos, aves y frutos, mientras la nutria predó casi exclusivamente peces (95%). Los índices de Levins de la anchura del nicho trófico del visón europeo, la gineta común y la nutria fueron 3,76, 3,77 y 1,10 respectivamente. Los solapamientos del nicho trófico durante otoño-invierno del visón europeo (índice de Pianka) respecto a la gineta común y la nutria euroasiática fueron 0,77 y 0,60, respectivamente. El tamaño medio de las truchas consumidas por las nutrias fue mayor que el de las consumidas por el visón europeo. Palabras clave: Visón europeo (Mustela lutreola), Nutria euroasiática (Lutra lutra), Gineta común (Genetta genetta), Dieta, España

Resposta positiva de la fauna a la millora en els contaminants bioacumulables: el cas dels peixos i de la llúdriga com a bioindicadors

Es presenten els resultats sobre els nivells de compostos bioacumulables (PCB, pesticides i metalls pesants) en els teixits de conills, peixos i depredadors (llúdriga i visons). Els nivells són menors en els organismes terrestres que en els aquàtics i han anat disminuint a la biosfera. Els animals han respost positivament, en diversos casos, estan recuperant la seva distribució antiga. Això té, a més, implicacions positives per als humans i per a una vida de més qualitat ambiental

Interacciones montaña-llanura frente al cambio global: desafíos y oportunidades en la gestión del territorio y de los recursos hídricos en Riegos del Alto Aragón

The transformation of rainfed agriculture lands into irrigated lands in the central sector of the Ebro Depression has represented a spectacular change in the cultivation conditions of a semi-arid territory affected by scarce and irregular precipitation. However, the new irrigation systems faced serious structural problems from the beginning due to the peculiar design of the irrigation system, the limitations of its objectives, the slow pace with which the infrastructures were built (reservoirs, canals and secondary ditches) and the conditioning of cultivated fields. This work focuses on the study of the limitations faced by Riegos del Alto Aragón due to the trend shown by water resources and their seasonal distribution as a result of the evolution of temperature and precipitation, the expansion of woody vegetation in mountain areas and the progressive silting up of the reservoirs. For this, the information available on Global Change in the Pyrenees has been reviewed and climatic and hydrological models have been applied. The necessary modernization has improved the irrigation systems and water use efficiency, and has allowed the expansion of much more productive and profitable crops. Paradoxically, modernization has also increased the water demand, and has made necessary to increase the system’s internal reserves through the construction of small reservoirs and ponds. This greater water demand coincides with a decreasing trend in water resources availability, due not only to the increase in average temperature, but also to changes in snowpack accumulation and melting dynamics in the Pyrenean headwaters and to forest expansion in old abandoned fields in the Pyrenean valleys, which reduces runoff generation and streamflow. It is foreseeable that most of these processes will continue or even accentuate in the medium- to long-term due to climate change. In addition, the progressive silting up of the reservoirs reduces the water storage capacity year after year. These processes, which highlight the interactions between mountain areas and the lowlands, will force in the medium term to reorganize the management of resources and irrigation procedures, as well as the progressive incorporation of crops with increasing added value that offset the rise in production costs linked to a stronger dependence of irrigation with respect to energy.La transformación del secano en regadío en el sector central de la Depresión del Ebro ha representado un cambio espectacular en las condiciones de cultivo de un territorio de características semiáridas y precipitaciones muy irregulares. Sin embargo, los nuevos regadíos se enfrentaron desde un principio a graves problemas estructurales debido al peculiar diseño del sistema de regadío, las limitaciones de sus objetivos, la lentitud con que se fueron construyendo las infraestructuras necesarias (embalses, canales y acequias secundarias) y el acondicionamiento de los campos de cultivo. Este trabajo se centra en el estudio de las limitaciones a que se enfrentan los regadíos de Riegos del Alto Aragón (R.A.A.) debido a la tendencia que muestran los recursos hídricos y su distribución estacional como consecuencia de la evolución de temperaturas y precipitaciones, la expansión de la superficie forestal y de matorrales en áreas de montaña y el progresivo aterramiento a que se enfrentan los embalses. Para ello se ha revisado la información disponible sobre el Cambio Global en el Pirineo y se han aplicado diversos modelos climáticos e hidrológicos. La necesaria modernización ha mejorado los sistemas de riego, ha incrementado la eficiencia en el uso de los recursos hídricos, y ha permitido la introducción de nuevos cultivos mucho más productivos y rentables. Paradójicamente, la modernización también ha conllevado un aumento del consumo de agua y ha obligado a incrementar las reservas internas del sistema mediante la construcción de pequeños embalses y balsas. Esta mayor demanda de agua coincide con una progresiva reducción en la disponibilidad de recursos hídricos, debida no solo al incremento de la temperatura media sino también a los cambios en la dinámica de la acumulación y fusión de nieve en alta montaña y a la expansión de bosques y matorrales en antiguos campos de cultivo abandonados en los valles pirenaicos, lo que reduce la capacidad de generación de escorrentía y los caudales fluviales. Se prevé que estas tendencias se acentúen en el medio y largo plazo como consecuencia del cambio climático. Además, el progresivo aterramiento de los embalses reduce año tras año la capacidad de almacenamiento de agua. Estos procesos, que ponen de manifiesto la importancia de las interacciones entre las áreas de montaña y las regiones de piedemonte, obligarán a medio plazo a reorganizar la gestión de los recursos y de los procedimientos de regadío, así como la progresiva incorporación de cultivos de mayor valor añadido que compensen el incremento de los costes de producción ligados a una mayor dependencia de los regadíos respecto de la energía

High trophic niche overlap between a native and invasive mink does not drive trophic displacement of the native mink during an invasion process

The pressure elicited by invasive species on native species significantly increases with the increase of the overlap of their ecological niches. Still, the specific mechanisms of the trophic displacement of native species during the invasion process are unclear. The effects of the invasive American mink (Neovison vison) on the critically endangered European mink (Mustela lutreola) was assessed by analyses of diet and niche overlap during the invasion process. To do this, the isotopic composition (δ13C and δ15N) of both species of mink and their four main types of prey was analysed. Significant trophic overlap between the native European mink and invasive American mink was found when they coexisted in sympatry. Furthermore, both mink species were characterised by significant individual variation in diet and no obvious change in diet of the native species in response to the arrival of the introduced species was observed. High niche overlap registered between both species in sympatry with no displacement in diet of the native mink in response to the arrival of the invasive mink is expected to have important consequences for the viability and conservation of the native mink populations, as it suggests high competitive pressure

Patterns and correlates of claims for brown bear damage on a continental scale

Wildlife damage to human property threatens human-wildlife coexistence. Conflicts arising from wildlife damage in intensively managed landscapes often undermine conservation efforts, making damage mitigation and compensation of special concern for wildlife conservation. However, the mechanisms underlying the occurrence of damage and claims at large scales are still poorly understood. Here, we investigated the patterns of damage caused by brown bears Ursus arctos and its ecological and socio-economic correlates at a continental scale. We compiled information about compensation schemes across 26 countries in Europe in 2005-2012 and analysed the variation in the number of compensated claims in relation to (i) bear abundance, (ii) forest availability, (iii) human land use, (iv) management practices and (v) indicators of economic wealth. Most European countries have a posteriori compensation schemes based on damage verification, which, in many cases, have operated for more than 30 years. On average, over 3200 claims of bear damage were compensated annually in Europe. The majority of claims were for damage to livestock (59%), distributed throughout the bear range, followed by damage to apiaries (21%) and agriculture (17%), mainly in Mediterranean and eastern European countries. The mean number of compensated claims per bear and year ranged from 0·1 in Estonia to 8·5 in Norway. This variation was not only due to the differences in compensation schemes; damage claims were less numerous in areas with supplementary feeding and with a high proportion of agricultural land. However, observed variation in compensated damage was not related to bear abundance. Synthesis and applications. Compensation schemes, management practices and human land use influence the number of claims for brown bear damage, while bear abundance does not. Policies that ignore this complexity and focus on a single factor, such as bear population size, may not be effective in reducing claims. To be effective, policies should be based on integrative schemes that prioritize damage prevention and make it a condition of payment of compensation that preventive measures are applied. Such integrative schemes should focus mitigation efforts in areas or populations where damage claims are more likely to occur. Similar studies using different species and continents might further improve our understanding of conflicts arising from wildlife damage