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The study of the competitive interactions between predators has traditionally been approached within the context of predatory behavior. By using a quasi‐experimental, non‐intrusive approach, we go beyond the classical view that predators only compete for living prey and disentangle the mechanisms of exploitative and interference competition between two charismatic apex predators, lions Panthera leo and spotted hyaenas Crocuta crocuta, at carcasses other than their own kills. Carcasses of different sizes were monitored in two study areas of South Africa: one with both lions and hyaenas and the other with hyaenas only. We found evidence of both symmetric exploitative competition and asymmetric interference competition. Interactions were strongly conditioned by carcass size, and co‐occurrence was mostly recorded at large ungulate carcasses. Interference competition seemed to dominate interspecific interactions, with lions having preferential access. However, interference while feeding did not exert any cost on the subordinate hyaenas, in terms of amount of ingested food and consumption rate, probably thanks to the reward provided by large carcasses in the form of abundant carrion, the use of lions to detect carcasses, and spatiotemporal segregation at the carcass‐scale. Securing a diverse carrion supply in terms of carcass size, including megaherbivore carcasses, may favor the coexistence of the largest African carnivores, especially in small protected areas. Overall, our study reveals mechanisms related to both the food resource heterogeneity and the competitor behavior that allow the coexistence of strongly interacting species. [ABSTRACT FROM AUTHOR]

Lead is highly toxic for wildlife, with pernicious consequences especially in long-lived predators. The causes of lead ammunition ingestion in Bonelli's eagle ( Aquila fasciata ) and its effects on breeding success were studied in one of the most important populations of this endangered species in Europe. Regurgitated pellets belonging to different pairs from 2004 to 2014 were analyzed, both in the breeding (1363 pellets from 12 territories) and non-breeding (172 pellets from 9 territories) seasons. From these territories, 57 molted feathers to study lead contamination were analyzed, and breeding success was monitored for 41 breeding attempts. The occurrence of lead shots in pellets was detected using X-ray photographs. Pellets were also used to describe eagle diet. Lead shots in pellets were present in 83.3% of the territories. The frequency of occurrence of lead shots in pellets (2.81% in spring and 1.31% in autumn) was primarily related to the consumption of red-legged partridge in the breeding season (when partridges are hunted from blinds using calling lures), and secondarily to rabbit consumption in the non-breeding season (coinciding with the main hunting season). Thus, our results indicate that injured small-game were the main source of lead contamination in the Bonelli's eagle. For the first time for a raptor species, a positive relationship between the frequency of occurrence of lead shots in pellets and lead concentration in eagles' feathers has been documented. Lead concentration in feathers (mean ± SD: 816 ± 426 μg kg − 1 , with no sex-related differences) was high for a species that rarely eats carrion or aquatic birds (the main prey-related lead source for raptors). This had negative effects on breeding success, which could jeopardize Bonelli's eagles in other European populations that are sustained by juvenile dispersal from the study population. Our work shows that some game modalities pose a potential threat to endangered raptors. [ABSTRACT FROM AUTHOR]

The author discusses the ongoing conservation efforts for the Iberian lynx, which was declared critically endangered by the International Union for the Conservation of Nature (IUCN) in 2002. It mentions the study conducted by Palomares and colleagues in 2011 which criticized conservation efforts for lacking continuity and being applied over a very small area. Information on the European Union's LIFE project for the conservation of Iberian lynx in Andalusia (ILLP) in Spain is presented.

Abstract: Monitoring of the age of mates, a method proposed to detect early warning signals for demographic trends in long-lived bird populations, showed different patterns when the study was performed on a single Bonelli’s eagle subpopulation of Andalusia (South of Spain) than when the whole region is taken into account. In this respect, we discuss the role of the spatial scale, the origin of reduction in non-natural mortality and the definition of the used age classes. For a correct monitoring of the age of mates in the Bonelli’s eagle, we propose the two age classes previously suggested, adult and non-adult, but paying particular attention to the late subadult individuals, specially when the monitoring is performed in a wide region by different field work groups. Likewise, it is necessary for monitoring age of breeders in long-lived species with deferred maturity to collect data from a sample well distributed over space, taking regularly into account pairs from the edge and from the centre of population. Besides, it is important to monitor those subpopulations with different known threats, providing them their relative importance among the whole population. Finally, conventional monitoring of the age of mates seems to generally be a reliable way to predict viability changes of bird populations, except when adult by adult replacements take place by reduction in juvenile mortality. [Copyright &y& Elsevier]

We analyse the factors influencing breeding success in a healthy population of Bonelli’s eagle (Hieraaetus fasciatus) from south–east Spain, a raptor that has suffered a serious decline in Europe. Between 18 and 33 pairs were annually monitored during the period 1994–2002. Several factors that may affect four breeding parameters were studied, namely human presence, vegetation, relief, climatic factors, intra- and inter-specific relationships, diet, prey abundance, nest building, adult mortality and age of reproduction. A consistently high breeding success was registered during the study period (productivity=1.43, SD=0.11), which was probably the result of high adult survival, adequate prey availability and mild weather conditions. However, a certain vulnerability to the presence of golden eagles (Aquila chrysaetos) and to human disturbance was observed. One interesting result was the reduced survival of young chicks on north-facing cliffs owing to colder conditions, which may partially explain the decline of the Bonelli’s eagle populations along its European distribution limits. We discuss the role of this healthy subpopulation in an Iberian metapopulation context, and propose that the potential interference of golden eagles should be taken into account when designing management strategies for Bonelli’s eagles. Finally, we pinpoint some conservation priorities and the importance of reducing the main causes of adult mortality (i.e. shooting and electrocution) to assure successful reproduction and survival of this species. [Copyright &y& Elsevier]

The former and present distribution of white clawed crayfish (Austropotamobius pallipes) in the province of Granada (southern Spain) is studied. Before 1980 it was widely distributed but at present only 16 populations exist. The decline is related to the presence of the freshwater red-swamp crayfish (Procambarus clarkii), an American species, vector of the aphanomycosis disease, introduced to the Iberian Peninsula in 1974 and now widely distributed in the watercourses and marshes of southern Spain. To establish an appropriate conservation policy for A. pallipes at its southernmost distribution limit, we studied watercourses from two river basins, Genil and Guadiana Menor, (tributaries of the Guadalquivir River). P. clarkii inhabits the medium to lower reaches of these two river basins (with its upper limit at 820 m a.s.l.). The distribution of this species was best explained by the effect of three of the 12 analyzed variables: altitude, water-current and minimum winter temperatures. From our results, the repopulation of the native crayfish is almost impossible in those reaches inhabited by P. clarkii. However, based on the habitat selection study, it is clear that upper reaches are unsuitable for the red-swamp crayfish, where the native white-clawed crayfish may have greater survival possibilities, and these sites can be used for future restocking projects. [Copyright &y& Elsevier]

In recent decades, intensive techniques of livestock raising have flourished, which has largely replaced traditional farming practices such as transhumance. These changes may have affected scavengers' behaviour and ecology, as extensive livestock is a key source of carrion. This study evaluates the spatial responses of avian scavengers to the seasonal movements of transhumant herds in south-eastern Spain. We surveyed the abundance of avian scavengers and ungulates, and analysed the factors affecting the space use by 30 GPS-tracked griffon vultures (Gyps fulvus). Griffons' foraging activity increased in the pasturelands occupied by transhumant herds, which implied greater vulture abundance at the landscape level during the livestock season. In contrast, facultative scavengers were more abundant without transhumant livestock herds, and the abundance of wild ungulates did not change in relation to livestock presence. We conclude that fostering transhumance and other traditional farming systems, to the detriment of farming intensification, could favour vulture conservation. [ABSTRACT FROM AUTHOR]

Background: Predation may potentially lead to negative effects on both prey (directly via predators) and predators (indirectly via human persecution). Predation pressure studies are, therefore, of major interest in the fields of theoretical knowledge and conservation of prey or predator species, with wide ramifications and profound implications in humanwildlife conflicts. However, detailed works on this issue in highly valuable -in conservation terms- Mediterranean ecosystems are virtually absent. This paper explores the predator-hunting conflict by examining a paradigmatic, Mediterranean-wide (endangered) predator-two prey (small game) system. Methodology/Principal Findings: We estimated the predation impact ('kill rate' and 'predation rate', i.e., number of prey and proportion of the prey population eaten, respectively) of Bonelli's eagle Aquila fasciata on rabbit Oryctolagus cuniculus and red-legged partridge Alectoris rufa populations in two seasons (the eagle's breeding and non-breeding periods, 100 days each) in SE Spain. The mean estimated kill rate by the seven eagle reproductive units in the study area was c. 304 rabbits and c. 262 partridges in the breeding season, and c. 237 rabbits and c. 121 partridges in the non-breeding period. This resulted in very low predation rates (range: 0.3-2.5%) for both prey and seasons Methodology/Principal Findings: We estimated the predation impact ('kill rate' and 'predation rate', i.e., number of prey and proportion of the prey population eaten, respectively) of Bonelli's eagle Aquila fasciata on rabbit Oryctolagus cuniculus and red-legged partridge Alectoris rufa populations in two seasons (the eagle's breeding and non-breeding periods, 100 days each) in SE Spain. The mean estimated kill rate by the seven eagle reproductive units in the study area was c. 304 rabbits and c. 262 partridges in the breeding season, and c. 237 rabbits and c. 121 partridges in the non-breeding period. This resulted in very low predation rates (range: 0.3-2.5%) for both prey and seasons [ABSTRACT FROM AUTHOR]

Hybridisation between domestic cats, Felis catus, and wildcats, Felis silvestris, could lead to the genetic extinction of the latter; therefore, checking hybridisation rates in wild populations is of vital conservation importance. However, detecting hybridisation in the field is particularly challenging. Here, we aim to test the success of morphological-based procedures for discriminating wildcats from their hybrids and domestic cats, against genetic methods. We checked 17 putative Spanish wildcats by using two different classification systems based on coat patterns. None of the putative wildcats analysed in this study seemed to have an admixed genotype. Concordance between genetic and pelage approaches was almost total: only one coat classification produced mixed results with detection of one potential hybrid. Assignment was worse when performed in the field after a rapid examination of coat characters. We conclude that classification systems using coat traits could serve as surrogates of genetic approaches, but only after careful examination of those characters with more discriminatory power. Thus, the control of hybrid populations in the field as a management tool to preserve the genetic identity of wild forms is problematic if based on crude approaches or incomplete classification systems. [ABSTRACT FROM AUTHOR]

1. A long-standing question in ecology is how natural populations respond to a changing environment. Emergent optimal foraging theory-based models for individual variation go beyond the population level and predict how its individuals would respond to disturbances that produce changes in resource availability. 2. Evaluating variations in resource use patterns at the intrapopulation level in wild populations under changing environmental conditions would allow to further advance in the research on foraging ecology and evolution by gaining a better idea of the underlying mechanisms explaining trophic diversity. 3. In this study, we use a large spatio-temporal scale data set (western continental Europe, 1968-2006) on the diet of Bonelli's Eagle Aquila fasciata breeding pairs to analyse the predator trophic responses at the intrapopulation level to a prey population crash. In particular, we borrow metrics from studies on network structure and intrapopulation variation to understand how an emerging infectious disease [the rabbit haemorrhagic disease (RHD)] that caused the density of the eagle's primary prey (rabbit Oryctolagus cuniculus) to dramatically drop across Europe impacted on resource use patterns of this endangered raptor. 4. Following the major RHD outbreak, substantial changes in Bonelli's Eagle's diet diversity and organisation patterns at the intrapopulation level took place. Dietary variation among breeding pairs was larger after than before the outbreak. Before RHD, there were no clusters of pairs with similar diets, but significant clustering emerged after RHD. Moreover, diets at the pair level presented a nested pattern before RHD, but not after. 5. Here, we reveal how intrapopulation patterns of resource use can quantitatively and qualitatively vary, given drastic changes in resource availability. 6. For the first time, we show that a pathogen of a prey species can indirectly impact the intrapopulation patterns of resource use of an endangered predator. [ABSTRACT FROM AUTHOR]

An important issue in population ecology is to disentangle different density-dependent mechanisms that may limit or regulate animal populations. This goal is further complicated when studying long-lived species for which experimental approaches are not feasible, in whose cases density-dependence hypotheses are tested using long-term monitored populations. Here we respond to some criticisms and identify additional problems associated with these kinds of observational studies. Current caveats are related to the temporal and spatial scales covered by population monitoring data, which may question its suitability for density-dependence tests, and to statistical flaws such as the incorrect control for confounding variables, low statistical power, the distribution of demographic variables, the interpretation of spurious correlations, and the often used stepwise series of univariate analyses. Generalised linear mixed models are recommended over other more traditional approaches, since they help to solve the above statistical problems and, more importantly, allow to properly test several hypotheses simultaneously. Finally, several management actions aimed to recover endangered species, such as supplementary feeding, might be considered as field experiments for further testing density-dependence hypotheses in long-lived study models. We expect these opportunities, together with the most adequate statistical tools now available, will help to better our understanding of density-dependent effects in wild populations. [ABSTRACT FROM AUTHOR]

Density-dependent breeding performance due to habitat heterogeneity has been shown to regulate populations of territorial species, since the progressive occupation of low quality territories as breeding density increases may cause a decline in the mean per capita fecundity of a population while variation in fecundity increases. Although the preemptive use of sites may relegate low quality individuals to sites of progressively lower suitability, few studies on density dependence have tried to separate the effects of territory quality from individual quality, and none have simultaneously considered the effects of heterospecific competitors. Using two long-term monitored populations, we assessed the relative contribution of habitat heterogeneity and bird quality (in terms of age) on the productivity of sympatric golden Aquila chrysaetos and Bonelli's eagles Hieraaetus fasciatus under different scenarios of intra- and inter-specific competition. Productivity (number of offspring fledged) varied among territories and average annual productivity was negatively related to its variability in both species and populations, thus giving some support to the habitat heterogeneity hypothesis. However, the effect of habitat heterogeneity on productivity became non-significant when parental age and local density estimators were included in multivariate analyses. Therefore, temporal changes in bird quality (age) combined with intra- and interspecific competition explained variability in territory productivity rather than habitat heterogeneity among territories per se. The recruitment of subadult breeders, a surrogate of mortality in eagles, strongly varied among territories. Habitat heterogeneity in productivity may thus arise not because sites differ in suitability for reproduction but because of differences in factors affecting survival. Territories associated with high mortality risks have a higher probability of being occupied by young birds, whose lower quality, interacting with the density competitors, leads to a reduction of productivity. Site-dependent variability in adult survival and interspecific competition may be extensive, but so far largely overlooked, factors to be seriously considered for the site-dependent population regulation framework. [ABSTRACT FROM AUTHOR]