Galvan I.,University Paris - Sud |
Aguilera E.,CSIC - Donana Biological Station |
Atienzar F.,University of Valencia |
Barba E.,University of Valencia |
And 16 more authors.
Journal of Avian Biology | Year: 2012
Feather mites are arthropods that live on or in the feathers of birds, and are among the commonest avian ectosymbionts. However, the nature of the ecological interaction between feather mites and birds remains unclear, some studies reporting negative effects of feather mites on their hosts and others reporting positive or no effects. Here we use a large dataset comprising 20 189 measurements taken from 83 species of birds collected during 22 yr in 151 localities from seven countries in Europe and North Africa to explore the correlation between feather mite abundance and body condition of their hosts. We predicted that, if wing-dwelling feather mites are parasites, a negative correlation with host body condition should be found, while a mutualistic interaction should yield positive correlation. Although negative relationships between feather mite abundance and host body condition were found in a few species of birds, the sign of the correlation was positive in most bird species (69%). The overall effect size was only slightly positive (r =0.066). The effect of feather mite abundance explained <10% of variance in body condition in most species (87%). Results suggest that feather mites are not parasites of birds, but rather that they hold a commensalistic relationship where feather mites may benefit from feeding on uropygial gland secretions of their hosts and birds do not seem to obtain a great benefit from the presence of feather mites. © 2012 The Authors.
Sos T.,Milvus Group
North-Western Journal of Zoology | Year: 2011
High spot polymorphism and a high frequency of blue spotted morph is reported from an Anguis colchica population in Romania (Rupea, Braşov County). Although the blue-spotted morph is mostly exhibited in males, the morph was recorded in females also - feature characteristic to the eastern clades. The blue-spotted morph in females here seems to be size-related. The blue-spotted females are larger, thus older females. The appearance of the blue spots is considered connected to the maturation process in the lizard. © 2011 NwjZ, Oradea, Romania.
Bancila R.I.,Ovidius University |
Ozgul A.,University of Zurich |
Hartel T.,Luneburg University |
Sos T.,Milvus Group |
Schmidt B.R.,University of Zurich
Ecography | Year: 2015
Understanding population dynamics is critical for the management of animal populations. Comparatively little is known about the relative importance of endogenous (i.e. density-dependent) and exogenous (i.e. density-independent) factors on the population dynamics of amphibians with complex life cycles. We examined the potential effects of density-dependent and -independent (i.e. climatic) factors on population dynamics by analyzing a 15-yr time series data of the agile frog Rana dalmatina population from Târnava Mare Valley, Romania. We used two statistical models: 1) the partial rate correlation function to identify the feedback structure and the potential time lags in the time series data and 2) a Gompertz state-space model to simultaneously investigate direct and delayed density dependence as well as climatic effects on population growth rate. We found evidence for direct negative density dependence, whereas delayed density dependence and climate did not show a strong influence on population growth rate. Here we demonstrated that direct density dependence rather than delayed density dependence or climate determined the dynamics of our study population. Our results confirm the findings of many experimental studies and suggest that density dependence may buffer amphibian populations against environmental stress. Consequently, it may not be easy to scale up from individual-level effects to population-level effects. © 2015 The Authors.
Vali T.,Uppsala University |
Vali T.,Estonian University of Life Sciences |
Dombrovski V.,National Academy of Sciences of Belarus |
Treinys R.,Institute of Ecology of Nature Research Center |
And 10 more authors.
Biological Journal of the Linnean Society | Year: 2010
Hybridization is a significant threat for endangered species and could potentially even lead to their extinction. This concern applies to the globally vulnerable Greater Spotted Eagle Aquila clanga, a species that co-occurs, and potentially interbreeds, with the more common Lesser Spotted Eagle Aquila pomarina in a vast area of Eastern Europe. We applied single nucleotide polymorphism (SNP) and microsatellite markers in order to study hybridization and introgression in 14 European spotted eagle populations. We detected hybridization and/or introgression in all studied sympatric populations. In most regions, hybridization took place prevalently between A. pomarina males and A. clanga females, with introgression to the more common A. pomarina. However, such a pattern was not as obvious in regions where A. clanga is still numerous. In the course of 16 years of genetic monitoring of a mixed population in Estonia, we observed the abandonment of A. clanga breeding territories and the replacement of A. clanga pairs by A. pomarina, whereby on several occasions hybridization was an intermediate step before the disappearance of A. clanga. Although the total number of Estonian A. clanga × A. pomarina pairs was twice as high as that of A. clanga pairs, the number of pairs recorded yearly were approximately equal, which suggests a higher turnover rate in interbreeding pairs. This study shows that interspecific introgressive hybridization occurs rather frequently in a hybrid zone at least 1700-km wide: it poses an additional threat for the vulnerable A. clanga, and may contribute to the extinction of its populations. © 2010 The Linnean Society of London.
Fehervari P.,Szent Istvan University |
Fehervari P.,Red footed Falcon Conservation Working Group |
Solt S.,Red footed Falcon Conservation Working Group |
Palatitz P.,Red footed Falcon Conservation Working Group |
And 6 more authors.
Animal Conservation | Year: 2012
The red-footed falcon Falco vespertinus is an enigmatic colonial raptor of high international conservation concern. One of the identified threatening factors responsible for the recent worldwide population decline is the shortage of suitable colonial nesting sites. In theory, this problem can easily be resolved by establishing artificial colonies. However, the key to a successful large scale nest-box scheme is to provide these artificial colonies in habitats suitable for the species. A Hungarian-Serbian project aimed to establish such nesting facilities in northern Serbia, although the lack of recent full-scale habitat surveys hindered the designation of the locations of these artificial nesting sites. We used five different species distribution models to model the distribution of nest sites on a 10×10km grid in Hungary and in Romania. We then used the ensemble predictions of the best performing models to project the probability of red-footed falcon nest site presence in northern Serbia (predicted area). The models showed that three variables (grasslands, pastures and broad-leaved forests) had the highest importance in describing the spatial pattern of nest sites in the modelling area. The extent of grasslands and pastures had positive effects, while broad-leaved forests had negative impact on the probability of nest site presence. The predictions classified all the currently known colonies in the predicted area correctly. Our results suggest that the potential breeding distribution in Serbia is similar to that of two decades ago, thus large-scale land use changes are presumably not responsible for the reported population decline. We have also reduced the extent of conservation target areas to 11.5%, allowing to pinpoint locations for these future nest box colonies, and also provided a basis for future conservation measures like allocating monitoring efforts and designating future Natura 2000 sites in Serbia. Animal Conservation © 2012 The Zoological Society of London.