Juan Mario Vargas
University of Málaga
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Featured researches published by Juan Mario Vargas.
Landscape Ecology | 2011
Pelayo Acevedo; Miguel Angel Farfán; Ana Luz Márquez; Miguel Delibes-Mateos; Raimundo Real; Juan Mario Vargas
In recent decades, Mediterranean landscapes have been experiencing more rapid changes in land use than usual, which have affected the ecology of the species inhabiting this biodiversity hotspot. Some studies have assessed the effect of such changes on biodiversity, but most of these were diachronic studies of population dynamics, or synchronic studies of species habitat selection, whereas few studies have simultaneously taken into account temporal changes in habitat composition and changes in species distribution. This study analysed the effects of land-use changes on the distribution of wild ungulates (Capreolus capreolus, Capra pyrenaica, Cervus elaphus and Sus scrofa). Using favourability function and Markov chain analysis combined with cellular automata, we addressed the following objectives: (i) to examine the environmental determinants of ungulate distribution in the past (1960s) and present (1990s), (ii) to model land use for 2040 to forecast future species distributions and (iii) to assess the biogeographical differences between the above-mentioned study periods (past–present and present–future). Species favourability was predicted to be more widely distributed in the present than in the past, but this increase varied across species. Areas predicted to be favourable in the present should remain stable in the future, but in addition there will be more new favourable areas not previously occupied by these species. The results are discussed from the perspective of the socio-economic relevance of wild ungulates in relation to some unfavourable areas of Mediterranean regions.
European Journal of Wildlife Research | 2006
Juan Mario Vargas; José Carlos Guerrero; Miguel Angel Farfán; Ana Márcia Barbosa; Raimundo Real
The red-legged partridge is a small game species widely hunted in southern Spain. Its commercial use has important socioeconomic effects in rural areas where other agrarian uses are of marginal importance. The aims of the present work were to identify areas in Andalusia (southern Spain) where game yields for the red-legged partridge reach high values and to establish the environmental and land use factors that determine them. We analysed 32,134 annual hunting reports (HRs) produced by 6,049 game estates during the hunting seasons 1993/1994 to 2001/2002 to estimate the average hunting yields of red-legged partridge in each Andalusian municipality (n=771). We modelled the favourability for obtaining good hunting yields using stepwise logistic regression on a set of climatic, topographical, land use and vegetation variables that were available as digital coverages or tabular data applied to municipalities. Good hunting yields occur mainly in plain areas located in the Guadalquivir valley, at the bottom of Betic Range and in the Betic depressions. Favourable areas are related to highly mechanised, low-elevation areas mainly dedicated to intensive dry crops. The most favourable areas predicted by our model are mainly located in the Guadalquivir valley.
Environmental Management | 2009
Miguel Delibes-Mateos; Miguel Angel Farfán; Jesús Olivero; Ana Luz Márquez; Juan Mario Vargas
Agricultural change has transformed large areas of traditional farming landscapes, leading to important changes in the species community assemblages in most European countries. We suspect that the drastic changes in land-use that have occurred in Andalusia (southern Spain) over recent decades, may have affected the distribution and abundance of game species in this region. This article compares the distribution of the main game species in Andalusia during the 1960s and 1990s, using data from maps available from the Mainland Spanish Fish, Game and National Parks Service and from recent datasets on hunting yield distributions, respectively. Big-game and small-game species were significantly segregated in southern Spain during the 1990s, as two clearly independent chorotypes (groups of species whose abundances are similarly distributed) were obtained from the classification analysis. In contrast, big-game and small-game species were not significantly segregated several decades ago, when there was only one chorotype consisting of small-game species and wild boar. The other three ungulates did not constitute a significant chorotype, as they showed positive correlations with some species in the group mentioned above. These changes seem to be a consequence of the transformations that have occurred in the Iberian Mediterranean landscape over the last few decades. The abandoning of traditional activities, and the consequent formation of dense scrubland and woodland, has led to an expansion of big-game species, and a decrease of small-game species in mountain areas. Moreover, agricultural intensification has apparently depleted small-game species populations in some agricultural areas. On the other hand, the increasingly intensive hunting management could be artificially boosting this segregation between small-game and big-game species. Our results suggest that the conservation and regeneration of traditional agricultural landscapes (like those predominating in the 1960s) should be a priority for the conservation of small-game species.
Biodiversity and Conservation | 2009
Miguel Angel Farfán; Juan Mario Vargas; Jesús Duarte; Raimundo Real
Wind farming is a relatively new form of obtaining energy that does not cause air pollution or other forms of environmental degradation associated with fossil fuel technologies. However, their use impacts on the environment, and the current rate at which they are being put into operation, combined with poor understanding of their medium- and long-term impact, is a cause of concern. Wind farms represent a new source of impact and disturbance for birds that adds to the long list of disturbance factors caused by human activity, such as power lines, radio and television towers, highways, glass windows, the practice of poisoning, illegal hunting and overexploitation. Due to the precarious situation of several bird species and their decline, any additional cause of mortality may be significant and should give rise to increased attention and research. The aim of the present work is to analyse the effect of the “Sierra de Aguas” wind farm on bird density and abundance, flight behaviour, and bird mortality. Mortality rates did not increase due to the presence of the wind turbines. The results suggest that the presence and operation of the wind turbines did not have a clearly negative effect on passerine birds present in the region where wind farm is located. However, raptors used the space around the wind farm with lower frequency than prior to its existence, which represented a displacement of the home range of these species.
Scientific Reports | 2015
John E. Fa; Jesús Olivero; Raimundo Real; Miguel Angel Farfán; Ana Luz Márquez; Juan Mario Vargas; Stefan Ziegler; Martin Wegmann; Brown D; Margetts B; Robert Nasi
We studied links between human malnutrition and wild meat availability within the Rainforest Biotic Zone in central Africa. We distinguished two distinct hunted mammalian diversity distributions, one in the rainforest areas (Deep Rainforest Diversity, DRD) containing taxa of lower hunting sustainability, the other in the northern rainforest-savanna mosaic, with species of greater hunting potential (Marginal Rainforest Diversity, MRD). Wild meat availability, assessed by standing crop mammalian biomass, was greater in MRD than in DRD areas. Predicted bushmeat extraction was also higher in MRD areas. Despite this, stunting of children, a measure of human malnutrition, was greater in MRD areas. Structural equation modeling identified that, in MRD areas, mammal diversity fell away from urban areas, but proximity to these positively influenced higher stunting incidence. In DRD areas, remoteness and distance from dense human settlements and infrastructures explained lower stunting levels. Moreover, stunting was higher away from protected areas. Our results suggest that in MRD areas, forest wildlife rational use for better human nutrition is possible. By contrast, the relatively low human populations in DRD areas currently offer abundant opportunities for the continued protection of more vulnerable mammals and allow dietary needs of local populations to be met.
Environmental Conservation | 2010
Miguel Delibes-Mateos; Miguel Angel Farfán; Jesús Olivero; Juan Mario Vargas
European rabbits (Oryctolagus cuniculus), a multifunctional keystone species in the Iberian Peninsula, have drastically declined over past decades. Rabbit decline has been frequently attributed to the arrival of two viral diseases. However, decline was apparently ongoing before the arrival of the diseases, as a consequence of habitat loss and fragmentation. In this paper, the effect on rabbit populations of land-use changes during recent decades in Andalusia (southern Spain) is analysed. Areas favourable for rabbits both at present and during the 1960s are identified, and the environmental and land-use factors that determine these areas established. In areas where the favourability for rabbits has changed during recent decades, main land use changes are assessed to identify possible factors explaining rabbit favourability in these areas. Areas favourable to rabbits are currently determined by factors similar to those during the 1960s; these areas have undergone geographic changes in recent decades, apparently as a consequence of land-use changes in Andalusia. The percentages of the variables that were positively associated with rabbit favourability in both models (current and 1960s) have declined in Andalusia as a whole, and in areas where rabbit favourability has decreased; hence environments suitable for rabbits have become impoverished. Conversely, in both models, environments suitable for rabbits increased in municipalities, where rabbit favourability also increased. The preservation of rabbit-friendly habitats should be a priority for the conservation of this key species in the western Mediterranean.
Wildlife Research | 2007
Juan Mario Vargas; Miguel Angel Farfán; José Carlos Guerrero; Ana Márcia Barbosa; Raimundo Real
In Andalusia, southern Spain, each game estate applies its own rules and presents its results in annual hunting reports, which have been mandatory for Spanish game estates since 1989. We used the information about hunting yields, included in 32 134 annual hunting reports produced during the period 1993/94 to 2001/02 by 6049 game estates, to determine the current distribution of hunting yields of big and small game species in Andalusia. Using generalised linear models and a geographic information system, we determined the most favourable municipalities to big and small game, respectively, and delimited potential areas to attain good hunting yields for big and small game at a 1-km2 resolution. Municipalities and areas favourable to big game are mainly located in the Sierra Morena and the westernmost fringe of the Betic Range, while those favourable to small game occupy the upper Guadalquivir River valley. There is a clear segregation between big and small game species according to the physiography and land uses of the territory. Big game species are typical of Mediterranean woodland areas, while the most emblematic small game species prefer agricultural areas. Our results provide a territorial ordination of hunting yields in southern Spain and have several potential applications in strategic planning for hunting activities and biodiversity conservation in Andalusia that can be extrapolated to other regions.
Italian Journal of Zoology | 2008
Miguel Angel Farfán; Juan Mario Vargas; José Carlos Guerrero; Ana Márcia Barbosa; Jesús Duarte; Raimundo Real
In this work we used the information of the Annual Hunting Reports (AHRs) to obtain a high‐resolution model of the potential favourableness for wild rabbit harvesting in Andalusia (southern Spain), using environmental and land‐use variables as predictors. We analysed 32,134 AHRs from the period 1993/2001 reported by 6049 game estates to estimate the average hunting yields of wild rabbit in each Andalusian municipality (n = 771). We modelled the favourableness for obtaining good hunting yields using stepwise logistic regression on a set of climatic, orographical, land use, and vegetation variables. The favourability equation was used to create a downscaled image representing the favourableness of obtaining good hunting yields for the wild rabbit in 1×1 km squares in Andalusia, using the Idrisi Image Calculator. The variables that affected hunting yields of wild rabbit were altitude, dry wood crops (mainly olive groves, almond groves, and vineyards), temperature, pasture, slope, and annual number of frost days. The 1×1 km squares with high favourableness values are scattered throughout the territory, which seems to be caused mainly by the effect of vegetation. Finally, we obtained quality categories for the territory by combining the probability values given by logistic regression with those of the environmental favourability function.
Bird Conservation International | 2017
Miguel Angel Farfán; Jesús Duarte; John E. Fa; Raimundo Real; Juan Mario Vargas
Wind power, as an alternative to fossil fuels, is increasingly common, and is expanding worldwide. Wind farms cause mortality of flying animals through collision with moving rotor blades, and from electrocution on associated power lines. Avian mortality rates have been estimated from birds collected under turbines over varying time intervals. However, without adequate and frequent monitoring, dead birds may be removed by scavengers and thus cause an underestimation of fatalities. In this paper, we tested experimentally for possible errors arising in avian mortality caused by the removal of carcasses by scavengers. At two different wind farms and associated power lines in southern Spain, we placed pigeon and quail carcasses to determine their disappearance rate. All dead pigeons were radio-tagged to estimate distances taken by scavengers. We found significant differences in carcass disappearance rates of pigeons and quails, and between wind farms and power lines but not between habitats. All quails and 45% of pigeon carcasses had disappeared by the third and fourteenth day, respectively. Less than half (40%) of the carcasses were found < 100 m from where they were deposited. While scavenging losses may vary according to the location of the wind farm or power line, here we propose a method to estimate correctly the number of fatalities at any wind farm and power line. Using this method, we can improve our understanding of the real impact of wind structures on adjacent bird communities, and adopt appropriate measures to ensure their conservation.
Pest Management Science | 2018
Miguel Delibes-Mateos; Miguel Angel Farfán; Carlos Rouco; Jesús Olivero; Ana Luz Márquez; John E. Fa; Juan Mario Vargas; Rafael Villafuerte
BACKGROUND Numerous small and medium-sized mammal pests cause widespread and economically significant damage to crops all over the globe. However, most research on pest species has focused on accounts of the level of damage. There are fewer studies concentrating on the description of crop damage caused by pests at large geographical scales, or on analysis of the ecological and anthropogenic factors correlated with these observed patterns. We investigated the relationship between agricultural damage by the European rabbit (Oryctolagus cuniculus) and environmental and anthropogenic variables throughout Spain. RESULTS Rabbit damage was mainly concentrated within the central-southern regions of Spain. We found that rabbit damage increased significantly between the early 2000s and 2013. Greater losses were typical of those areas where farming dominated and natural vegetation was scarce, where main railways and highways were present, and where environmental conditions were generally favourable for rabbit populations to proliferate. CONCLUSION From our analysis, we suggest that roads and railway lines act as potential corridors along which rabbits can spread. The recent increase in Spain of such infrastructure may explain the rise in rabbit damage reported in this study. Our approach is valuable as a method for assessing drivers of wildlife pest damage at large spatial scales, and can be used to propose methods to reduce human - wildlife conflict.