The traffic load near large cities may show dramatic cyclical changes induced by weekend tourism, and this could induce cyclical changes in the activity patterns of wildlife. We studied a 19-km-long section of a road that crossed a high-use raptor area near a large city in Spain. We observed 18 raptor species along this segment of the road, including some threatened species, such as the Spanish Imperial Eagle (Aquila adalberti). The number of cars increased dramatically on Saturdays and Sundays, so we assessed the effect of varying traffic loads on raptor behavior by recording all birds of prey as close or distant to the road during working days and weekend days. On weekends, the occurrence of Spanish Imperial Eagles and vultures decreased near the road. The occurrence of other species did not change between working days and weekend days. The activity decrease on weekends by Imperial Eagles and other large raptors suggests that there are weekly cycles in raptor activity. Weekly cycles in wildlife caused by human activity are a source of concern in conservation biology. Efecto del Tráfico de Fin de Semana sobre el Uso de Espacio por Rapaces Resumen: El tráfico en carreteras cercanas a las grandes urbes muestra incrementos cíclicos debidos al turismo de fin de semana, lo que podría inducir ciclos semanales en los patrones de actividad de las aves de presa. Cerca de una gran ciudad estudiamos una sección de 19 Km en una carretera que cruza una de las mejoresáreas para las rapaces de toda España. Observamos 18 especies de rapaces en elárea de estudio, incluyendo varias en peligro de extinción, como eláguila imperial ibérica (Aquila adalberti), una de las rapaces en mayor peligro de extinción del mundo. Registramos los movimientos de todas las rapaces observadas en una malla de cuadrículas UTM clasificadas como cercanas o lejanas a la carretera para estudiar si las observaciones de rapaces eran diferentes en días de semana y en fines de semana, dado que hubo un incremento muy marcado en la intensidad de tráfico los fines de semana. Comprobamos que eláguila imperial y los buitres utilizaban con menor frecuencia las inmediaciones de la carretera durante los fines de semana, restringiendo su actividad a lasáreas remotas y poco transitadas. Los cambios cíclicos en actividad humana durante los fines de semana podrían por tanto inducir también cambios cíclicos en los patrones de actividad † †Current address: Instituto de Agrobiotecnología y Recursos Naturales, Consejo Superior de Investigaciones Cientificas, Carretera Disturbance of Raptors by Road Traffic 727de especies amenazadas como eláguila imperial. Los ciclos semanales de actividad en la fauna tienen mucho interés para la biología de la conservación, ya que son consecuencia de la actividad humana.
The Montagu's harrier (Circus pygargus) is a ground-nesting raptor that breeds mainly in cereal crops in western Europe. We evaluate how the use of agricultural habitats may affect population sustainability in this species, based on simulation analyses, and explore how conservation measures could be optimized. Probability of extinction increased with decreasing harrier productivity, and this trend was accentuated when the carrying capacity (maximum number of breeding pairs) decreased. Harrier productivity in agricultural habitats is strongly affected by harvesting activities. An average of 60% of nestlings in agricultural areas of France and the Iberian Peninsula would perish in the absence of conservation measures. These losses would make populations unsustainable, if no immigration occurred. Simulation analyses showed that connectivity between populations through natal dispersal could allow persistence of threatened populations even in the absence of conservation measures. The probability of extinction of four hypothetical populations connected through natal dispersal would be lowest if one of those populations were fully protected (or fully productive), even if the other ones were unprotected. Montagu's harriers are semi-colonial, and populations could be considered as a compound of subpopulations (the colonies). Additionally, Montagu's harriers bred more frequently in areas where food abundance was high, and where the number of fledglings produced in the previous reproductive attempt was high. These factors could be used to develop sustainable and efficient conservation plans, identifying and protecting the most productive and stable colonies in agricultural areas, and further exploring experimentally factors that are likely to attract and maintain harriers in protected areas.
Oxidative stress is the imbalance between the production of pro-oxidant substances and the level of antioxidant defenses, which leads to oxidative damage. It has been proposed that senescence is the result of accumulated oxidative damage throughout life. In birds, the sources of individual variability in oxidative stress are still poorly understood. Among these sources, age, as related to senescence, should be particularly relevant. Furthermore, recent findings suggest that breeding effort may also deeply influence susceptibility to oxidative stress. However, there is still no evidence of a link between breeding effort and oxidative damage in any vertebrate. Here we analyzed 288 captive red-legged partridges (Alectoris rufa) across a wide age range (i.e., 1-8 yr old), thus including potentially senescent birds. In spite of limitations due to the crosssectional approach, results revealed that old birds produced less offspring and endured higher levels of oxidized glutathione and peroxidized lipids in erythrocytes than did middle-aged individuals. Old birds also showed higher plasma total antioxidant status and uric acid levels than did younger birds, but lower amounts of circulating carotenoids. Furthermore, hatching success was negatively correlated to lipid peroxidation in females but not in males, supporting the hypothesis that breeding effort promotes oxidative damage.
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