Large Birds of Prey, Policies That Alter Food Availability and Air Traffic: a Risky Mix for Human Safety

Raptors are considered to pose one of the greatest aviation bird strike risk. We investigated raptor bird strikes reported at the largest Spanish airport (Adolfo Suárez Madrid Barajas; AS-MB) from 2009 to 2016 to determine the factors contributing to the increased incidences and develop recommendations to mitigate the risks. We hypothesized that increased raptor bird strikes resulted from changes in foraging and dispersal patterns of Iberian Peninsula vultures (Aegypius spp. and Gyps spp.) after 2004-2005. We used information on raptor bird strikes obtained from official databases and published studies, reported incidences of raptor bird strikes and their characteristics (i.e., time, location, species involved), data collected about raptor flight heights, and estimates of relative abundance of large raptors and their prey species obtained through standardized surveys conducted in the high priority aviation area around the airport to assess bird strike risks. Our field work was conducted from June 2014 to May 2016. We confirmed a direct relationship between the relative abundance of the raptors studied and their prey species in the priority aviation areas. Raptor bird strike risks increased during spring and summer when food sources were abundant in locations where flight altitudes of aircraft werenew, scarcer, and more distant food sources, enhancing the likelihood of overlap with air traffic corridors. Although further studies on aviation risk are needed, our results suggest the need implement immediate remedial management actions to alter vulture habitat quality by reducing food sources in sensitive areas, and providing alternative food resources at distances sufficiently far from commercial airports

Is it necessary managing carnivores to reverse the decline of endangered prey species? Insights from a removal experiment of mesocarnivores to benefit demographic parameters of the pyrenean capercaillie

This is an open access article distributed under the terms of the Creative Commons Attribution License.-- et al.Mesopredator control has long been used to alleviate the effect of elevated predation pressure on vulnerable, threatened or valuable species. However, the convenience of using mesopredator controls is technically questionable and scientifically-sound research is therefore required to evaluate the impact of predation on prey case by case. In this study we evaluated the effect of the alteration of terrestrial mesopredator dynamics on the demographic parameters of a relict capercaillie Tetrao urogallus aquitanicus population currently in decline for which the impact of predation has not previously been assessed. We used a six-year mesocarnivore removal experiment (2008-2013) together with seven-years of previous demographic information on capercaillies (1999-2007) within a before-after controlimpact (BACI) design to evaluate the effect of mesocarnivore removal on capercaillie demographic parameters and on spatial behaviour of the most frequent predatory mesocarnivores of the capercaillie (Martes spp. and red fox Vulpes vulpes). Using a dynamic siteoccupancy approach, the reduction of mesocarnivore population levels as a result of removal was clear for marten species, mainly during key months for capercaillie reproduction, but not for the red fox. Our results show that the breeding success of capercaillies was enhanced in areas where carnivores were removed and was inversely related to the occupation level of the studied mesocarnivores, although being only significant for Martes spp. Moreover, capercaillie predation rates were lower and adult survival seemingly higher in treatment during the removal phase. Cost-effective, long-term management interventions to ensure the recovery of this threatened capercaillie population are discussed in the light of the results. At our study area, the decision for implementing predation management should be included within a broader long-term conservation perspective. In this regard, a more feasible and sustainable management intervention in ecological and economic terms may be to balance the impact of mesocarnivores on capercaillies through the recovery of apex predators.The present work was commissioned by the Spanish Ministry of Environment, and the GALLIPYR-POCTEFA 2007 cofunded by the Generalitat de Catalunya and the European Union, who provided support in the form of salaries for authors [RM-O, IA, JP, JM-I], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. JVLB received a postdoctoral grant “Juan de la Cierva” from the Spanish Ministry of Economy and Competitiveness.”Peer Reviewe

Larger size and older age confer competitive advantage: dominance hierarchy within European vulture guild hierarchy within European vulture guild

Competition for limiting natural resources generates complex networks of relationships between individuals, both at the intra- and interspecifc levels, establishing hierarchical scenarios among diferent population groups. Within obligate scavengers, and especially in vultures, the coevolutionary mechanisms operating during carrion exploitation are highly specialized and determined in part by agonistic behavior resulting in intra-guild hierarchies. This paper revisits the behavioral and hierarchical organization within the guild of European vultures, on the basis of their agonistic activities during carrion exploitation. We used a dataset distilled from high-quality videorecordings of competitive interactions among the four European vulture species during feeding events. We found a despotic dominance gradient from the larger species to smaller ones, and from the adults to subadults and juveniles, following an age and body size-based linear pattern. The four studied species, and to some extent age classes, show despotic dominance and organization of their guild exerting diferential selection to diferent parts of the carrion. The abundance of these parts could ultimately condition the level of agonistic interactions. We discuss the behavioral organization and the relationship of hierarchies according to the feeding behavior and prey selection, by comparing with other scavenger guilds

Reconciling the conservation of endangered species with economically important anthropogenic activities: interactions between cork exploitation and the cinereous vulture in Spain

Limitation of disturbing activities around the breeding areas of protected species is not always possible, if these activities are economically important and have, in addition, positive effects on protecting the habitats of those protected species. Searching for optimal solutions making commercial exploitation of natural resources compatible with biodiversity conservation is thus of concern to managers and policy makers. This is the case of the cinereous vulture Aegypius monachus, breeding primarily in cork-oak woodland, and cork exploitation, a traditional socio-economic activity carried out in several Mediterranean countries, and critical for the maintenance of this important habitat. We studied the effects of this anthropogenic activity on the behaviour and breeding success of breeding cinereous vultures in Spain. For the adults, the probability of nest abandonment was dependent on the distance of workers from the nest and the level of noise; activities within 500m from the nest were likely to cause abandonment of the nest by adults, if the level of noise was intermediate or loud. Neither the size of the working group nor the use of machines per se, had any effect on the probability of nest abandonment. Pairs in an area of the colony exposed to intrusive anthropogenic activity had 20% lower breeding success than those in the same colony that were not exposed to these disturbances. If the application of buffer zones of 500m is not possible (as is likely given the economic losses involved), several alternatives are recommended based on our results to minimize the impact of these activities, in particular to diminish the noise level of cork extraction activities. Observational studies like this help understanding the magnitude of the problem and finding alternative solutions for harmonizing conservation and economic development.This study was carried out within the framework of the monitoring programme of the LIFE 03/NAT/E/0050 project ‘Conservation of the Spanish imperial eagle, cinereous vulture and black stork’, implemented by the Fundacion CBD-Habitat in conjunction with the autonomous communities of Castilla-La Mancha, Extremadura and Madrid and the Ministerio de Medio Ambiente, Medio Rural y Marino.Peer Reviewe

Fumarel Cariblanco, Chlidonias hibrida

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Effect of Methodological and Ecological Approaches on Heterogeneity of Nest-Site Selection of a Long-Lived Vulture

The application of scientific-based conservation measures requires that sampling methodologies in studies modelling similar ecological aspects produce comparable results making easier their interpretation. We aimed to show how the choice of different methodological and ecological approaches can affect conclusions in nest-site selection studies along different Palearctic meta-populations of an indicator species. First, a multivariate analysis of the variables affecting nest-site selection in a breeding colony of cinereous vulture (Aegypius monachus) in central Spain was performed. Then, a meta-analysis was applied to establish how methodological and habitat-type factors determine differences and similarities in the results obtained by previous studies that have modelled the forest breeding habitat of the species. Our results revealed patterns in nesting-habitat modelling by the cinereous vulture throughout its whole range: steep and south-facing slopes, great cover of large trees and distance to human activities were generally selected. The ratio and situation of the studied plots (nests/random), the use of plots vs. polygons as sampling units and the number of years of data set determined the variability explained by the model. Moreover, a greater size of the breeding colony implied that ecological and geomorphological variables at landscape level were more influential. Additionally, human activities affected in greater proportion to colonies situated in Mediterranean forests. For the first time, a meta-analysis regarding the factors determining nest-site selection heterogeneity for a single species at broad scale was achieved. It is essential to homogenize and coordinate experimental design in modelling the selection of species' ecological requirements in order to avoid that differences in results among studies would be due to methodological heterogeneity. This would optimize best conservation and management practices for habitats and species in a global context

The Cantabrian capercaillie: A population on the edge

The capercaillie Tetrao urogallus - the world's largest grouse- is a circumboreal forest species, which only two remaining populations in Spain: one in the Cantabrian mountains in the west and the other in the Pyrenees further east. Both have shown severe declines, especially in the Cantabrian population, which has recently been classified as “Critically Endangered”. To develop management plans, information on demographic parameters is necessary to understand and forecast population dynamics. We used spatial capture-recapture (SCR) modeling and non-invasive DNA samples to estimate the current population size in the whole Cantabrian mountain range. In addition, for the assessment of population status, we analyzed the population trajectory over the last 42 years (1978–2019) at 196 leks on the Southern slope of the range, using an integrated population model with a Dail-Madsen model at its core, combined with a multistate capture-recapture model for survival and a Poisson regression for productivity. For 2019, we estimate the size of the entire population at 191 individuals (95% BCI 165–222) for an estimated 60 (48–78) females and 131 (109–157) males. Since the 1970s, our study estimates a shrinkage of the population range by 83%. The population at the studied leks in 2019 was at about 10% of the size estimated for 1978. Apparent annual survival was estimated at 0.707 (0.677–0.735), and per-capita recruitment at 0.233 (0.207–0.262), and insufficient to maintain a stable population. We suggest work to improve the recruitment (and survival) and manage these mountain forests for capercaillie conservation. Also, in the future, management should assess the genetic viability of this population.Ministerio para la Transición Ecológica y el Reto Demográfico (18MNES002 and 19MNES001); Junta de Castilla y León (EN-16/19); Gobierno del Principado de Asturias (SCP025/2019)].Peer reviewe

Minimising Mortality in Endangered Raptors Due to Power Lines: The Importance of Spatial Aggregation to Optimize the Application of Mitigation Measures

Electrocution by power lines is one of the main causes of non-natural mortality in birds of prey. In an area in central Spain, we surveyed 6304 pylons from 333 power lines to determine electrocution rates, environmental and design factors that may influence electrocution and the efficacy of mitigation measures used to minimise electrocution cases. A total of 952 electrocuted raptors, representing 14 different species, were observed. Electrocuted raptors were concentrated in certain areas and the environmental factors associated with increased electrocution events were: greater numbers of prey animals; greater vegetation cover; and shorter distance to roads. The structural elements associated with electrocutions were shorter strings of insulators, one or more phases over the crossarm, cross-shaped design and pylon function. Of the 952 carcasses found, 148 were eagles, including golden eagle (Aquila chrysaetos), Spanish imperial eagle (Aquila adalberti) and Bonelli's eagle (Aquila fasciata). Electrocuted eagles were clustered in smaller areas than other electrocuted raptors. The factors associated with increased eagle electrocution events were: pylons function, shorter strings of insulators, higher slopes surrounding the pylon, and more numerous potential prey animals. Pylons with increased string of insulators had lower raptor electrocution rates than unimproved pylons, although this technique was unsuccessful for eagles. Pylons with cable insulation showed higher electrocution rates than unimproved pylons, both for raptors and eagles, despite this is the most widely used and recommended mitigation measure in several countries. To optimize the application of mitigation measures, our results recommend the substitution of pin-type insulators to suspended ones and elongating the strings of insulators

Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species

13 Pág.Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constrains symbiont populations. We parameterized metabolic theory equations to investigate how bird species' body size and the body size of their feather mites relate to mite abundance according to four potential energy (uropygial gland size) and space constraints (wing area, total length of barbs and number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance across 106 passerine bird species (26,604 individual birds sampled), using phylogenetic modelling and quantile regression. Feather mite abundance was strongly constrained by host space (number of feather barbs) but not by energy. Moreover, feather mite species' body size was unrelated to the body size of their host species. We discuss the implications of our results for our understanding of the bird-feather mite system and for symbiont abundance in general.Funding was provided by the Ministry of Science and Innovation (research project CGL2011-24466 to R.J., and CGL2015-69650-P to R.J. and D.S.). Manecorro Ringing Station (ICTS-RBD-CSIC) received economic support from Junta de Andalucía. We thank Doñana National Park for the authorizations and support during the preparation of the ringing programmes. We thank all the ringers who helped us measure the primaries at Manecorro Ringing Station. J.D. was supported by the European Commission (H2020-MSCA-IF-2019, INTROSYM:886532). S.F.-G. was supported by the Spanish Ministry of Economy and Competitiveness (CGL2010-15734/BOS). L.Z.G. was supported by a found from the National Research, Development, and Innovation Office—NKFIH (K-135841). O.G. was supported by the Spanish Ministry of Economy (Ref. CGL2014-56041-JIN). M.M.L. was supported by ‘la Caixa’ Foundation (grant ID100010434). H.C.P. was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant. J.C.S. was supported by funds from the Ministry of Science and Innovation (CGL-2020 PID2020- 114907GB-C21). C.I.V. was supported by the Romanian Ministry of Research, Innovation and Digitization (CNCS-UEFISCDI; project no. PN-III-P1-1.1-TE-2021-0502). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe