Search

Many animals make behavioural changes to cope with winter conditions, being gregariousness a common strategy. Several factors have been invoked to explain why gregariousness may evolve during winter, with individuals coming together and separating as they trade off the different costs and benefits of living in groups. These trade-offs may, however, change over space and time as a response to varying environmental conditions. Despite its importance, little is known about the factors triggering gregarious behaviour during winter and its change in response to variation in weather conditions is poorly documented. Here, we aimed at quantifying large-scale patterns in wintering associations over 23 years of the white-winged snowfinch Montifringilla nivalis nivalis. We found that individuals gather in larger groups at sites with harsh wintering conditions. Individuals at colder sites reunite later and separate earlier in the season than at warmer sites. However, the magnitude and phenology of wintering associations are ruled by changes in weather conditions. When the temperature increased or the levels of precipitation decreased, group size substantially decreased, and individuals stayed united in groups for a shorter time. These results shed light on factors driving gregariousness and points to shifting winter climate as an important factor influencing this behaviour.

Coexistence of humans and large carnivores is a major challenge for conservation and management, especially in human‐modified landscapes. Ongoing recovery of some large carnivore populations is good conservation news, but it also brings about increased levels of conflict with humans. Compensation payments and preventive measures are used worldwide as part of conservation programmes with the aim of reducing such conflicts and improving public attitude towards large carnivores. However, understanding the drivers triggering conflicts is a conservation priority, which helps prevent and reduce damages. Here, we have analysed the spatio‐temporal patterns of brown bear Ursus arctos damages to apiaries, crops and livestock in the two small, isolated and endangered bear populations in northern Spain. The increase in the number of damages varied in parallel with the increase in bear numbers, which is probably a primary cause determining the occurrence on damages. Damages also varied among years, seasons and bear populations and seemed to mainly depend on the local availability of natural food items, weather conditions and the availability of apiaries and livestock. Fluctuating availability of food items may explain the frequency of conflicts, which is yet another call to apply preventive measures in carnivore damage to human property in seasons and years when natural food availability is lower than usual. Understanding and preventing damage is in turn essential to mitigate conflicts where humans and large carnivores share the same landscape.

Many countries promote wildlife observation as part of ecotourism offerings. The brown bear Ursus arctos is among the most targeted species for ecotourism in Notth America and Europe, making it an ideal candidate to examine the consequences of wildlife viewing upon the species. As bear viewing often occurs in sensitive places where bears congregate for mating, rearing young and/or feeding, it is important to evaluate potential positive and negative effects of different viewing practices. Here we reviewed available information on bear viewing practices and their effects on bears, people and ecosystems. Behavioural, physiological and ecological aspects related to bears are reviewed from three different perspectives: ecotourism consequences for bears, direct bear-human interactions and social impacts of bear ecotourism. Because bear viewing can have positive and negative impacts on both bear populations and bear-human interactions, it is important to carefully evaluate every practice associated with bear viewing at a local scale. Because bear populations around the world have diverse population statuses and different management regimes, successful procedures and rules effective in one place do not guarantee that they will be adequate elsewhere. Effective management of bear viewing practices requires a better understanding of the consequences for bears, the mechanisms behind observed bear reactions to humans, and the results of bear habituation. Because inappropriate beat viewing practices can lead to processes such as food conditioning and habituation, which can have serious consequences for both people and bears, regulations on bear ecotourism are urgently needed to minimize unintended consequences of bear viewing practices.

[IN] Recent research has demonstrated the important role of visual communication in nocturnal birds. Achromatic plumage patches (i.e., pigment-free white feathers) with high levels of contrast against dark backgrounds are excellent candidates for visual signaling in the dark or at twilight, when differences in color may be less effective. In this study, with the goal of investigating the signaling role of certain achromatic plumage patches, we examined the characteristics and patterns of the brightness (i.e., total reflectance) of Eurasian Eagle-Owl (Bubo bubo) white feather patches for both young birds and adult individuals. Our results showed that (1) the total reflectance of young birds' white feathers differed significantly from that of adult owls' white feathers; (2) the brightness differed between the sexes in adults only, with females showing a significantly higher reflectance than males; (3) the total reflectance of the white patch around a young bird's mouth was positively correlated with brood size; (4) the total reflectance of the white badge on the throat of adults was positively correlated with their hematocrit values; (5) an assortative mating scenario based on the brightness of an individual's white badge was deemed possible; and (6) we did not detect any significant relationship in the levels of reflectance for related individuals: the young and their parents were not found to be distinguishable based on the brightness of their white feather patches., [ES] Trabajos recientes han demostrado la importancia del papel que las señales visuales desempeñan en la comunicación de las aves nocturnas. Los plumajes acromáticos (es decir, aquellos libres de pigmentos) con altos niveles de contraste contra un fondo oscuro son los mejores candidatos para enviar señales visuales en la noche o en horas crepusculares, cuando las diferencias de color pueden ser menos efectivas. Con el objetivo de investigar el papel en la señalización de ciertos parches de plumas acromáticas, estudiamos las características y los patrones de brillo (es decir, la reflectancia total) de la mancha blanca presente en polluelos y en adultos de Bubo bubo. Los resultados mostraron que (1) la reflectancia total de la mancha blanca de los polluelos difirió significativamente de la de los adultos; (2) en adultos existen diferencias en el brillo de la mancha blanca en función del sexo, siendo las hembras las que tienen valores más altos de reflectancia; (3) la reflectancia total de la mancha blanca de los polluelos está positivamente relacionada con el tamaño de nidada; (4) en el caso de los adultos, existe una relación entre la mancha blanca en la garganta y el valor de hematocrito de los individuos; (5) es posible que la mancha blanca de los búhos adultos actúe como una señal en un posible escenario de emparejamiento selectivo; y (6) no detectamos ninguna diferencia en el brillo de la mancha dentro de los núcleos familiares, es decir, los individuos de cada familia no parecen diferenciarse en función de los rasgos de la mancha blanca.

Replacement clutches can be crucial to the breeding success of avian species, although several factors may influence their outcome and the quality of chicks. Here we compare first and replacement clutches of Eagle Owls in terms of chick quality, timing of breeding, and number of eggs and fledglings .We hypothesize that the propensity to abandon nests and start a new clutch could have evolved because females are able to produce chicks that are as good as the ones of the first clutch. We found that nestlings in replacement clutches were not significantly different from nestlings in first clutches, in terms of immune system and body condition; nor were there significant differences in clutch and brood size. Our findings may be explained by the fact that clutches were laid early in the season, perhaps by high-quality parents, and that food resources are plentiful in the study area. In order to maximize fitness, individuals have to adjust optimally the investment of resources in different life-history traits. Thus, the re-nesting behaviour of Eagle Owls may be seen as a way to solve the trade-off between one trait (survival) favoured over another (reproduction), when one of them has a disproportionate effect on fitness.