Francisco Guil

Minimising mortality in endangered raptors due to power lines: the importance of spatial aggregation to optimize the application of mitigation measures.

Electrocution by power lines is one of the main causes of non-natural mortality in birds of prey. In an area in central Spain, we surveyed 6304 pylons from 333 power lines to determine electrocution rates, environmental and design factors that may influence electrocution and the efficacy of mitigation measures used to minimise electrocution cases. A total of 952 electrocuted raptors, representing 14 different species, were observed. Electrocuted raptors were concentrated in certain areas and the environmental factors associated with increased electrocution events were: greater numbers of prey animals; greater vegetation cover; and shorter distance to roads. The structural elements associated with electrocutions were shorter strings of insulators, one or more phases over the crossarm, cross-shaped design and pylon function. Of the 952 carcasses found, 148 were eagles, including golden eagle (Aquila chrysaetos), Spanish imperial eagle (Aquila adalberti) and Bonellis eagle (Aquila fasciata). Electrocuted eagles were clustered in smaller areas than other electrocuted raptors. The factors associated with increased eagle electrocution events were: pylons function, shorter strings of insulators, higher slopes surrounding the pylon, and more numerous potential prey animals. Pylons with increased string of insulators had lower raptor electrocution rates than unimproved pylons, although this technique was unsuccessful for eagles. Pylons with cable insulation showed higher electrocution rates than unimproved pylons, both for raptors and eagles, despite this is the most widely used and recommended mitigation measure in several countries. To optimize the application of mitigation measures, our results recommend the substitution of pin-type insulators to suspended ones and elongating the strings of insulators.

Factors influencing the presence of the cinereous vulture Aegypius monachus at carcasses: food preferences and implications for the management of supplementary feeding sites

Abstract We studied the factors that determine the presence of the cinereous vulture Aegypius monachus at 134 carcasses experimentally distributed in Special Protection Areas for Birds (SPA) in western and central Spain. Our goals were to assess the use of these carcasses and by-products in order to find out the cinereous vultures food preferences and thus provide recommendations for the management of specific vulture restaurants for this species. Our results suggest that the number of cinereous vultures that come to feed on the carcasses is related to the quantity of biomass present and to the types of pieces of the provided food. Cinereous vultures prefer individual, medium-sized muscular pieces and small peripheral scraps of meat and tendon. The time that elapses before the cinereous vultures begin to consume a carcass depends on the biomass delivered, the number of pieces into which it is divided, and the type categories of the provided food. The population density of the species in our study area and the breeding stage seem to determine the time invested in feeding at the carcasses. These results may help managers to optimise the creation of vulture restaurants and favour their use by cinereous vultures.

Provision of artificial warrens as a means to enhance native wild rabbit populations: what type of warren and where should they be sited?

In Spain, wild rabbits are essential for some highly endangered species, and, therefore, many actions have been undertaken to increase their populations. In the present study, artificial warrens are provided as a means to increase shelter for native wild rabbit populations in a given area. We evaluate the use of three types of warrens by rabbits and the effect on that use of five habitat characteristics at two spatial scales (500 × 500-m grids and 25-m plots). To evaluate that use, we identified pre-established signs at the entrances to each warren, and based on this, we calculated occupancy rate and activity. Our results indicate that rabbit abundance within a grid is the only variable which simultaneously explains both the greater occupancy and the higher activity in the artificial warrens located in that grid. Some 73.2% of the grids showed signs of rabbit use at the time of the evaluation. However, the pre-existing rabbit populations within the grids were not quantified and, hence, we cannot state that the warrens contributed to an increase in the rabbit abundance. Regarding the habitat, our results reveal that warrens should be situated in grids with food coverage of less than 50%, while the use of each individual refuge is greater where food availability in the immediate surroundings is at least 20% and shelter at least 50%. The tube warrens showed significantly greater rabbit use than the other types while there was little difference between the stone and pallet warrens in terms of use.

The role of ponds as feeding habitat for an umbrella species: best management practices for the black stork Ciconia nigra in Spain

To establish recommendations for wetland man- agement that promote wildlife diversity in Mediterranean habitats we examined the factors that determine feeding habitat selection by the black stork Ciconia nigra in ponds. The black stork is considered an umbrella species because it is threatened, requires large foraging ranges in priority areas, is selective in its choice of diet and nesting sites, and inhabits a characteristic biological community with endemic and threatened taxa. Eighty-five ponds were monitored in central and western Spain to detect the stork feeding. At the same time, pond variables that could affect black stork feeding preferences were periodically evaluated. Generalized linear mixed models were used to analyse principal components obtained from groups of factors related to structural, location and ecological conditions. The black stork selects ponds distant from roads, with a large surface area, high water level, shallow shores, low turbidity, few traces of wild ungulates on the shores, a high diversity of fish and amphibian species, and a vegetated perimeter, in flat and open areas. Potential factors affecting feeding behaviour are discussed. We suggest measures for pond construction and management that could favour this species in particular and biodiversity in general in the Mediterranean environment.

Wildfires as collateral effects of wildlife electrocution: An economic approach to the situation in Spain in recent years

The interaction between wildlife and power lines has collateral effects that include wildfires and Carbon Dioxide (CO2) emissions. However, currently available information is scarce and so new approaches are needed to increase our understanding of this issue. Here, we present the first analysis of wildfires and their incidence as a result of this interaction in Spain during the period 2000-2012. Amongst the 2788 Power-Line Mediated Wildfires (PLMW recorded) during this period, 30 records of Fauna Mediated Wildfires (FMW) were found, with an average affected vegetation cover of 9.06ha. Our findings suggest that no significant differences were observed between the amount of affected surface area due to fauna mediated wildfires and power-line mediated wildfires. In both cases, a space-grouping trend was observed. In terms of changing trends over time, after the first incident detected in 2005, the number of incidents increased until 2008, year in which the percentage of wildfires caused by wildlife stabilized at approximately 2.4% of all power-line-induced wildfires. Population density and road abundance were variables that better explained PLMW whereas for FMW, the models that included land use and raptor abundance. In the multivariate model, FMW emergence was positively related with population density, percentage of grazing areas and Natura 2000 cover, and predatory abundance; and negatively with the percentage of forested area. No significant differences were observed between the species of birds that caused wildfires and the species of ringed birds killed by electrocution. The economic and environmental impact due to necessary repairs, the loss of biodiversity and CO2 emissions represent an estimated net value of €7.6-12.4M for the period 2000-2012, which indicates the importance of the economic and environmental costs associated with wildfires.