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Rebelo H.,University of Bristol | Rebelo H.,Institute Ciencias Agrarias Of Vairao | Jones G.,University of Bristol
Journal of Applied Ecology | Year: 2010

We evaluated the accuracy of presence-only modelling for predicting the distribution of rare species, when data are scarce and usually collected with sampling biases. We modelled the potential distribution in Portugal of one of the rarest European bats Barbastella barbastellus and subsequently ground-validated predictions by using acoustic transects. We used ecological niche factor analysis (ENFA) and maximum entropy (Maxent) modelling to build distribution models of B. barbastellus, and determined which ecological factors were more relevant for each model. As ENFA only accepts continuous variables, we built one Maxent model using the same variables as ENFA and another using land cover as a categorical variable. Ecological niche factor analysis and both Maxent models predicted similar areas of occurrence in central and northern regions of Portugal, although ENFA predicted suitable habitat over a wider range. Conversely, there was substantial disagreement on the location of high-suitability areas in the south. This could be a consequence of a different choice of important variables made by each model. Native woodland and average temperature were the most relevant variables for Maxent, while in ENFA B. barbastellus was linked to higher altitudes although avoiding production forests and infrastructures. Threshold-independent and -dependent statistics showed that Maxent models outperformed ENFA, probably as a consequence of divergent predictions in the new areas of occurrence. Overall, 15 new B. barbastellus sites were discovered and known distribution was extended c. 100 km to the south. Synthesis and applications. Our results support the use of presence-only modelling as an indispensible tool for survey design as shown by the discovery of B. barbastellus populations outside of the previously known range. ENFA seems to be more suited to determining a species' potential distribution, although failing to extrapolate it. In contrast, Maxent is better suited to determining a species' realized distribution. It was successful in predicting occurrence in previously unsurveyed areas and can be recommended as a technique for determination of a conservative distribution for a species. Maxent modelling would greatly aid biodiversity conservation, especially when it is necessary to develop survey plans or first assessments of a species' distribution. © 2010 The Authors. Journal compilation © 2010 British Ecological Society. Source


Torres J.,University of Porto | Brito J.C.,Institute Ciencias Agrarias Of Vairao | Vasconcelos M.J.,Instituto Investigacao Cientifica Tropical | Catarino L.,Instituto Investigacao Cientifica Tropical | Honrado J.,University of Porto
Biological Conservation | Year: 2010

Pan troglodytes verus is considered one of the most endangered primates in the world due to habitat loss or degradation, and it is considered extinct in several regions of West-Africa. This study aims at developing a model that predicts habitat suitability for chimpanzee under different land cover scenarios and supports a multi-temporal analysis of the recent habitat evolution in southern Guinea-Bissau. The model, built using a maximum entropy framework, is spatially explicit, uses eco-geographic variables derived from landscape compositional, structural and functional attributes, and is based on nest location data collected in the field. The results show that the developed model has good levels of reliability and the map produced through its application reveals a current extension of 752 km2 of adequate habitat in a 2723 km2 study area. Forest related EGVs (ecogeographical variables) had the higher importance for the model production. Habitat suitability maps produced for three dates in the last three decades show that there has been a marked decrease in habitat extension and in connectivity to neighbouring regions. We analyse the implications of these results in possible strategies for the conservation of chimpanzees in Guinea-Bissau. © 2009 Elsevier Ltd. All rights reserved. Source


Amorim F.,University of Evora | Amorim F.,Lda. Rua de Ansiao | Rebelo H.,Institute Ciencias Agrarias Of Vairao | Rebelo H.,University of Bristol | Rodrigues L.,Instituto da Conservacao da Natureza e da Biodiversidade
Acta Chiropterologica | Year: 2012

Our study aims to determine how different climatic variables influence bat activity and mortality at wind farms in Portugal. The study was conducted from March to October 2007 at a wind farm with 20 turbines located in Northern Portugal. Bat activity was determined by ground bounded acoustic sampling, while mortality was assessed through fatality searches around each turbine. Sampling occurred weekly and activity was measured the night before fatality search. The highest activity and mortality rates were from Nyctalus leisleri and Pipistrellus pipistrellus. The majority of activity and mortality (95% and 94% in that order) occurred from August to October and both were significantly correlated with wind speed, temperature and relative humidity; mortality also appeared to be influenced by wind direction. Our results show that it is possible to establish a relationship between ground bounded activity and mortality. Our results are relevant for the implementation of effective minimization measures and, therefore, for bat conservation in the Mediterranean region. Specifically, our results show that nearly all (94%) of bat mortality at wind farms happens from August to October, at temperatures higher than 13.O°C, and wind speeds lower than 5.0 m.s-1. © Museum and Institute of Zoology PAS. Source


Roads are one the most important human agents of transformation, producing direct non natural, negative effects in wildlife. This work quantified road mortality on amphibian and reptile species in the Hoces del Alto Ebro y Rudrón Natural Park (north of Spain). In 2005, two types of roads (seven secondary and one main road) were sampled by car in order to detect road-killed specimens. Geographical Information Systems (GIS) and G-tests were used for analysing data, and mortality indexes (MI, number of specimens / 100 km sampled) were used as descriptors of the mortality risk on wild species. A total of 291 specimens was recorded, 115 amphibians belonging to four species and 176 reptiles belonging to 13 species. Bufo bufo represented more than 88% of the amphibians with MI peaks in spring and autumn. Natrix maura, Vipera aspis and V. latastei were the most frequently found road-killed reptiles (54.5%), presenting the two viper species MI peaks in spring. The number of road-kills was significantly higher in secondary roads than in the main one and also significantly high in well-preserved habitats. Three sections of high mortality were identified, all located in secondary roads that go through the Natural Park, enhancing the importance of habitat fragmentation as a major threat in biodiversity conservation. Management actions to reduce and/or eliminate the intensity of road mortality should be addressed in the Natural Park's management plan and detailed studies should be performed to evaluate the effectiveness of installing traffic signs, road barriers and/or under-road passages. Source


Rebelo H.,University of Bristol | Rebelo H.,Institute Ciencias Agrarias Of Vairao | Tarroso P.,Institute Ciencias Agrarias Of Vairao | Jones G.,University of Bristol
Global Change Biology | Year: 2010

There has been considerable recent interest concerning the impact of climate change on a wide range of taxa. However, little is known about how the biogeographic affinities of taxa may affect their responses to these impacts. Our main aim was to study how predicted climate change will affect the distribution of 28 European bat species grouped by their biogeographic patterns as determined by a spatial Principal Component Analysis. Using presence-only modelling techniques and climatic data (minimum temperature, average temperature, precipitation, humidity and daily temperature range) for four different climate change scenarios (IPCC scenarios ranging from the most extreme A1FI, A2, B2 to the least severe, B1), we predict the potential geographic distribution of bat species in Europe grouped according to their biogeographic patterns for the years 2020-2030, 2050-2060 and 2090-2100. Biogeographic patterns exert a great influence on a species' response to climate change. Bat species more associated with colder climates, hence northern latitudes, could be more severely affected with some extinctions predicted by the end of the century. The Mediterranean and Temperate groups seem to be more tolerant of temperature increases, however, their projections varied considerably under different climate change scenarios. Scenario A1FI was clearly the most detrimental for European bat diversity, with several extinctions and declines in occupied area predicted for several species. The B scenarios were less damaging and even predicted that some species could increase their geographical ranges. However, all models only took into account climatic envelopes whereas available habitat and species interactions will also probably play an important role in delimiting future distribution patterns. The models may therefore generate 'best case' predictions about future changes in the distribution of European bats. © 2009 Blackwell Publishing Ltd. Source

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