Standing out from the crowd: are patagial wing tags a potential predator attraction for harriers (Circus spp.)?

et al.Wing tags have been used on many bird species to facilitate individual recognition, although tags are not only conspicuous for humans but may also attract the attention of potential predators. During a Peregrine Falcon Falco peregrinus monitoring program (1997-2011) we collected prey remains from the nests of 37 Peregrine territories in the Basque Country, Northern Spain. We identified 3,127 prey items representing 132 bird species. In the 2009 breeding season, we found, for the first time, four Hen Harrier Circus cyaneus remains and the two wings with orange wing tags of a Montagu's Harrier Circus pygargus in one nest, 1 year later we found in the same nest eight Montagu's Harrier remains, one of them with wing tags, and in 2011 we found eight more Montagu's Harriers, one of them marked. Simultaneously, in the breeding season of 2010, the remains of another Montagu's Harrier were found in other Peregrine nest and two wings with orange and blue wing tags in the perch of a third pair. Our data thus shows an increase of predation rate of harriers by Peregrines; we discuss whether this could be related to the increasing use of wing tags in this species, and thus whether wing tags may have potential negative effects on the birds. We argue that further studies about the impact of identification techniques, and wing-tags in particular, on the survival of target species should be carried out.Peer Reviewe

Azor común – Accipiter gentilis (Linnaeus, 1758)

Aves - Orden Falconiformes - Familia Accipitridae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/.A comprehensive review of the natural history of the Northern Goshawk Accipiter gentilis in Spain.Peer reviewe

Halcón peregrino – Falco peregrinus Tunstall, 1771

Aves - Orden Falconiformes - Familia Falconidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/. Versiones anteriores: 21-06-2005; 8-03-2007; 10-03-2008; 30-07-2012A comprehensive review of the natural history of the Peregrine falcon Falco peregrinus in Spain.Peer reviewe

Effect of nest composition, experience and nest quality on nest-building behaviour in the Bonelli's Eagle.

In bi-parentally built nests, there is evidence to suggest that nests are extended phenotypic signals that accurately indicate the quality of the building parent/s. Raptors often use a variety of materials to build their nests (natural, such as branches, but also non-natural objects), presumably due to their insulating properties, their suitability to advertise occupancy of the nest, and to decrease pathogen and parasite loads. However, in raptors where both sexes collaborate in nest construction, it is unclear whether nest building (taking the amount of material carried to the nest as the potential predictor) is an indicator of parental quality, and whether the effort expended by both sexes could constitute an honest signal of parental quality to their partners. Between 2011 and 2016, we monitored 16 nests of Bonelli's Eagles (Aquila fasciata), and we examined data on sex, type of material brought to the nest, breeding experience, nest quality, timing, and nest-building investment prior to egg-laying from 32 identifiable Bonelli's Eagles during the pre-laying period to investigate the relative contribution of the sexes to the amount of nest material gathered. Our results indicate that sex is not a determining factor in nest-building effort, and that females did not increase their parental effort in response to the male's contribution, and supply of materials did not increase during the pre-laying period. In contrast, our models showed that: (1) the type of material supplied to the nest by both sexes varied significantly throughout the pre-laying period and (2) nest-building effort was determined by individual experience and nest quality. Therefore, our study suggests that male nest-building behaviour and investment by Bonelli's Eagles cannot be considered as an extended phenotypic signal. The differential use of hard and green material by both sexes in the early and late stages of nest-building period, and the fact that the more experienced individuals contributed a larger amount of material on low quality nests, are discussed in the contexts of signaling nest occupancy to conspecifics and competitors and the decrease of ectoparasite loads during the pre-laying period

Predictive models of habitat preferences for the Eurasian eagle owl Bubo bubo: A multiscale approach

Habitat preference of eagle owls Bubo bubo were examined through comparing habitat composition around 51 occupied cliffs and 36 non-occupied cliffs in Alicante (E Spain). We employed Generalized Linear Models to examine patterns of habitat preference at three different spatial scales: nest site (7 kim2), home range (25 km2), and landscape (100 km2). At the nest site scale, occupied cliffs were more rugged, had a greater proportion of forest surface in the surroundings, and were further from the nearest paved road than unoccupied cliffs. Additionally, probability of having an occupied cliff increased when there was another occupied territory in the surroundings. At both the home range scale and the landscape scale, high probabilities of presence of eagle owls were related to high percentages of Mediterranean scrubland around the cliffs, which are the preferred habitat of European rabbits Oryctolagus cuniculus, the main prey of the owls. We suggest a hierarchical process of habitat selection in the eagle owl concerning suitable trophic resources at the broadest scales and adequate sites for breeding and roosting at the smallest scale. However, it should be noted that some structural features such as the proximity of roads were not necessarily avoided by the owls, but their presence were possibly constrained by systematic killing of individuals. Our paper provides new evidence for the requirement of multi-scale approaches to gain insight into both the different limiting factors for the persistence of populations and the role of individual perception of the environment in the evolution of habitat selection.Peer Reviewe

Paíño europeo – Hydrobates pelagicus Linnaeus, 1758

Aves - Orden Procellariiformes - Familia Hydrobatidae en la Enciclopedia Virtual de Vertrebrados Españoles, http://www.vertebradosibericos.org/.A comprehensive review of the natural history of the Storm Petrel (Hydrobates pelagicus) in Spain.Peer reviewe

Reduced food availability induces behavioural changes in Griffon Vulture Gyps fulvus

In natural conditions, Griffon Vultures typically show shy behaviour and escape by flying if approached by humans. According to the state-dependent foraging theory, Griffon Vultures should modify their foraging behaviour depending on food availability and predation risk, humans being the main potential predator. We tested the Reaction Time (RT) and Flight Initiation Distance (FID) in five different artificial feeding schemes over three years in which food availability in the field varied significantly. The first scenario was set in a so-called “vulture restaurant”, in which government employees feed vultures that may exhibit tame behaviour and stay within a few meters from a feeding person. Scenario 2 involved similar conditions, but here the researchers not employees placed the food in the vulture restaurant. The vultures did not land at the restaurant until one day had passed, and they flew away when people approached them within 250 m. The third scenario was established in a local zoo several months after the closure of the vulture restaurant. Here, employees fed captive vultures that were often accompanied by wild birds that landed to take food. The RT was 14.2 min and the FID was 50 m. The fourth scenario was established during the subsequent breeding season in a mountain where vultures were fed by the authors of the present study. The RT was 2.8 min and the FID was 15.2 m. The fifth scenario was established in another mountain after the breeding season. Now, the RT was 19.2 min and the FID was 52.2 m. These results demonstrate the ability of vultures to evaluate the predation risk depending on food availability and their state of hunger, and their ability to modify their behaviour from “natural” caution (”shyness”) towards a more tolerant (”fearless”) behaviour.Peer reviewe

Breeding behaviour and time-activity budgets of Bonelli’s Eagles Aquila fasciata: marked sexual differences in parental activities

[Capsule]: Differences in parental investment between sexes and stage of the breeding period were found in Bonelli’s Eagles Aquila fasciata.[Aims]: To describe the sexual differences in parental behaviour of Bonelli’s Eagles and to assess the sex-specific pattern of variation in parental investment in relation to the breeding period.[Methods]: Between 2006 and 2016, we monitored the parental behaviour of 11 pairs of Bonelli’s Eagles during the incubation and chick-rearing periods in southeastern Spain. Observations were made using 20–60× telescopes from points overlooking the territory at a distance of about 500–800 m from the nest.[Results]: Our results reveal a marked division in parental duties in Bonelli’s Eagles. Females invested more effort in incubation, nest attendance, chick feeding and nest-building, while males contributed more to food provisioning. Nest attendance and feeding by females decreased with time, and both parents adjusted their provisioning effort in relation to nestling age. Most changeovers took place during the middle of the day, when male provisioning rates and temperatures reach their maximum.[Conclusion]: Intersexual differences are discussed in the context of the prey capture difficulty hypothesis, which proposes that intra-pair prey differences, due to large sexual size dimorphism, should be particularly advantageous among raptors that pursue agile prey.Peer reviewe

Efecto de la marea negra del Prestige sobre el halcón peregrino en el País Vasco

Informe original disponible en la web de Icarus, Estudios Medioambientales, S.L., que ha participado en su elaboración: http://www.icarus.es/La afección de la marea negra del petrolero Prestige sobre el Halcón Peregrino durante el primer año ha sido patente. Se ha comprobado que se da una afección directa, aunque evidentemente, de menor magnitud que la esperada en aves relacionadas directamente con el medio marino. Las probabilidades de alimentarse sobre presas contaminadas son evidentes y aumentarán conforme pase el tiempo y siga existiendo fuel. Además, la contaminación de las cadenas tróficas intermedias produce un efecto de bioacumulación añadido en las presas del halcón. Por lo que las concentraciones de elementos perniciosos pueden incrementarse de una forma lenta pero continua. Este es el verdadero problema de la marea negra sobre el halcón, que provoca problemas en la fase de la reproducción, bien por malfuncionamiento de las gónadas, bien por efectos letales en los embriones de los huevos, o bien por afecciones a largo plazo en los pollos. Además de provocar la muerte a corto-medio plazo de los ejemplares adultos.Por lo tanto, en este primer informe se van a exponer los resultados obtenidos durante el seguimiento de las poblaciones de Halcón Peregrino en Bizkaia, comparándolos con seis años de estudios previos. Los resultados permitirán valorar el grado y la magnitud de la afección en su primer episodio (periodo de reproducción de 2003).Peer reviewe

Safety in numbers? Supplanting data quality with fanciful models in wildlife monitoring and conservation

Ecologists and conservation biologists seem increasingly attracted to sophisticated modelling approaches, sometimes at the expense of attention to data quality and appropriateness of fieldwork design. This dissociation may lead to a loss of perspective promoting biological unrealities as conclusions, which may be used in conservation applications. We illustrate this concern by focusing on recent attempts to estimate population size of breeding birds at large scales without any explicit testing of the reliability of the predictions through comparison with direct counts. Disconnection of analysts from ¿nature¿ can lead to cases of biological unrealities such as that used here to illustrate such trends. To counter this risk, we encourage investment in well-rounded scientists or more collaborative, multi-disciplinary teams capable of integrating sophisticated analyses with in-depth knowledge of the natural history of their study subjects.Peer Reviewe