Francisco José Purroy

Lack of scientific evidence and precautionary principle in massive release of rodenticides threatens biodiversity: old lessons need new reflections

Pesticides are widely used throughout the world to control agricultural pests. Owing to their well identified side-effects on wildlife, the release of high quantities of pesticides to the environment should always require responsible use of both science-based information and the precautionary principle, however decision making in wildlife management and conservation is not systematically supported by scientific evidence. This is particularly worrying when decision making involves release of toxic substances to the environment, as often occurs in rodent plague control. Poorly-informed management decisions to control a rodent plague can adversely affect wildlife, especially when chemical-based treatments are generically designed and applied on a broad scale, with high economic cost. Evidence-based and environmentally sustainable management should be used to control rodent plagues in Spain.

Food Habits of Brown Bears (Ursus arctos) in the Cantabrian Mountains, Spain

The diet of the European brown bear ( Ursus arctos ) was studied in the Cantabrian Mountains, Spain, by analyzing the frequency of occurrence and percent volume of 929 feces collected 1983–1988. Plant material was the predominant food during spring and summer (84.1 and 44.8% of total volume, respectively) until more nutritious foods became available. During autumn and winter, hard mast formed the greatest part of the diet constituting 61.5 and 49.9% of the total volume, respectively. Livestock and wild ungulates were supplementary foods for bears, usually obtained by scavenging rather than predation. Insects were consumed year-round, ranging from 19.5% volume in summer to 0.1% in winter. Remnant deciduous forests and upland creek drainages were prime feeding areas of bears.

Habitat assessment of a relict brown bear Ursus arctos population in northern Spain

Abstract We assess the habitat quality of a small remnant population of Eurasian brown bears Ursus arctos in northern Spain based on a habitat evaluation procedure and analysis of bear distribution and road density. Habitat evaluation was based on our knowledge of bear habitat requirements using a combination of radiolocation and sign data and analysis of four variables (forest cover, elevation, distance to nearest village, distance to nearest roadway). Herein, we use those results to calculate habitat suitability indices for 1 km 2 UTM cells over 3500 km 2 of bear range, by summing scores (from 0 to 1) for each variable. Roughly 15% of the study area was classified as high-quality bear habitat. In secondary bear range (sporadic presence) the average unpaved road density was more than twice as high compared to that in primary, year-round, range, and was highest in areas outside of the bear range. The applicability of our habitat evaluation procedure to other small remnant Eurasian bear populations is proposed.

Sign surveys for estimating trend of a remnant brown bear Ursus arctos population in northern spain

Brown bears Ursus arctos in Spains Cantabrian Mountains are continuing to decline in numbers despite their protected status. Recovery plans for this population stress the need for monitoring of occupied habitat using non-intrusive methods. A population monitoring program to estimate bear abundance indices by quantifying tracks and scats (sign surveys) along a network of survey routes was designed. Each route was divided into consecutive 1,6-km segments, which comprised the basic sampling unit, and were assumed to provide independent observations. During a 3-year pilot study surveys were run twice per year, totaling 70 routes, including 950 segments, and covering over 1,500 km annually. Averages of 0.06 sign per segment were observed; only 4% of the segments had sign. It is concluded that the present sampling scheme does not provide enough statistical power to accurately detect significant declines in population level. The difficulties of monitoring trends of low density populations using surveys are recognized. However, by increasing the sampling intensity, more reliable information and greater precision of the population trend estimate should be obtainable. Thus, a future monitoring strategy should be based on increasing sampling intensity and closely monitoring bear distribution and occurrence.

The role of fallow in habitat use by the Lesser Kestrel during the post-fledging period: inferring potential conservation implications from the abolition of obligatory set-aside

The maintenance of fallows has been shown to prevent the loss of farmland biodiversity caused by agricultural intensification. These are mainly introduced as part of both obligatory and voluntary set-aside schemes. However, the obligatory set-aside has recently been abolished by the Common Agricultural Policy Health Check. In this study, we examine the role of fallow in fine-grained habitat use by a threatened farmland bird (Lesser Kestrel) during summer in northwestern Spain. To analyze Lesser Kestrel occurrence, we used generalized linear models, a theoretic-information approach and a hierarchical partitioning analysis. The best AIC-based models explaining occurrence of Lesser Kestrels showed that fallow was the more important habitat type followed, to a lesser extent, by dry cereal stubble and field margin. In contrast, irrigated crops negatively influenced occurrence. Heterogeneity of crop mosaic was not important in explaining occurrence of Lesser Kestrel. Fallows, like dry cereal stubbles and field margins, seem to be suitable for foraging given the abundance of high food resources and their availability due to shorter vegetation cover. The abolition of the obligatory set-aside could reduce the total surface of fallow land (approximately 40.9%), likely affecting habitat use by Lesser Kestrel through an increase of other non-preferred crops (e.g., irrigated crops) or by decreasing food resources. Agri-environment schemes focusing on the maintenance of low-intensive farming systems with a mosaic of crops and semi-natural habitats interspersed should be promoted in premigratory areas to maintain Lesser Kestrel.

La integración del conocimiento sobre la Cordillera Cantábrica: hacia un observatorio inter-autonómico del cambio global

Delgado L.A. 2018. Landscape Heterogeneity and tree species diversity in a tropical forest. Development and validation of a methodological proposal. Ecosistemas 27(1): 105-115. Doi.: 10.7818/ECOS.1475 Many landscapes exist as unstable spatial-temporal mosaics where changes in patterns of biodiversity are affected by nature processes and the dynamic interaction between social and ecological factors. It is a consequence of the natural dynamics of socio-economic systems that regulate man-made tropical forests. However, a significant proportion of studies have made generalizations about the relative values of biodiversity, without taking into account the high levels of internal heterogeneity in the biophysical properties and land uses of each site. The purpose of this study is to propose and validate a methodology to delimit the heterogeneity of the landscape based on criteria that integrate the coupling of human-ecological systems such as: space-time dynamics of deforestation and fragmentation; complexity of the landscape structure; current and historical land use and biophysical variability. For this, the use of satellite images, landscape metrics, field work, documentary review and multivariate analysis were combined. The proposed methodology is intended to help guide the empirical delimitation of landscape heterogeneity as a prerequisite for the selection of similar landscapes and forest patches in studies of the diversity of tree species, in order to provide an opportunity to control the possible difficulties caused by variability in the proportion of forests, landscape configuration and successional states, in estimating its effects on forest richness and floristic composition.