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The greenery and arthropod nest composition has been studied in a population of Bonelli's eagle Hieraaetus fasciatus in south-east Spain, relating them to the plant availability within territories and breeding success of pairs. Greenery was invariably from trees and shrubs, with pine and oak species accounting for 78% of the nest composition in weight. All eagle pairs with Pinus pinaster availability in territories actively selected it for nest greenery. This pine species is characterized by a high level of aromatic compounds, particularly b-pinene, highly repellent for insects. The amount of pine greenery in the nest was correlated with a lower presence of ectoparasites in that nest (blow fly larvae, Protocalliphora), and higher breeding success of pairs. We discuss whether a coevolutionary process between parasites and their hosts has guided a particular nesting strategy of the eagles to improve their breeding success.

Four non-exclusive hypotheses have been proposed to explain the alternative nest-building behaviour of raptors: (1) nests as an advertising signal in territories, (2) frustration nests, (3) competition avoidance by nest-site and (4) reduction of nest ectoparasites. We report here data collected during an observational study of a population of Bonelli's Eagle Hieraaetus fasciatus in southeastern Spain. Our data does not support the first two hypotheses based on the closeness of nests within territories, the lack of correlation between the number of nests and the distance to neighbours and the construction of secondary nests at similar frequencies after breeding failures as after successes. In contrast, the construction of alternative nests to avoid competition with other cliff-nesting raptor species breeding nearby was clearly important since 30% of the pairs obtained some direct benefit from the existence of alternative nests within their territories. We also found abundant Coleoptera (Dermestidae) and Diptera (Carnidae, Calliphoridae and Phoridae) as ectoparasites in nests, and the alternative use of nests, synergetically with the presence of greenery as mechanisms for avoiding ectoparasites, was an important factor for the breeding success of the eagle. Our data suggest that competition avoidance and, in particular, the reduction of nest ectoparasite hypotheses are the more plausible explanations for the maintenance of alternative nests in raptors.

Aim To assess the impact of certain climatic variables on the breeding success of some populations of Bonelli's eagle (Hieraaetus fasciatus V. 1822) throughout its latitudinal distribution range, in order to account for recent and differential declines in populations.Location Western Mediterranean, from southern Morocco to southern France.Methods Seven populations were considered for the latitudinal distribution range of the species. Data from 1052 breeding attempts were taken from the literature and, for each population, breeding success was measured as the mean number of fledglings per pair per year. Breeding success, as a dependent variable, was related to five geographical and climatic variables (latitude, mean annual temperature, mean minimum temperature of the coldest month, mean maximum temperature of the hottest month and mean annual precipitation) as independent variables, through some regression models, which take into account the multicolinearity of the variables.Results All the analyses agreed that average annual temperature was an important factor associated with the breeding success of the species in each region, and accounted for up to 97% of the variance of the breeding success throughout a latitudinal gradient in the study area. Main conclusionsThe low breeding success of the northern populations (probably because of climatic constraints) and the tendency of juveniles to disperse southwards, diminishes recruitment in those populations. Therefore, as human pressure and habitat destruction causes high adult and pre-adult mortality of the species throughout its entire latitudinal range, disturbances in the northern populations have more profound effects, thereby explaining observed population declines.

Ecosystem restoration requires that habitat requirements of all species be considered. Among animal communities in Mediterranean ecosystems, reptiles, as ectothermic vertebrates, need refuges for avoidance of extreme environmental temperatures, concealment from predators, and oviposition sites. In 1998, a massive amount of tailings broke out of the holding pond of the Aznalcó llar mine (southwestern Spain) and polluted the Guadiamar river valley. After the accident, a soil-and vegetation restoration program began, and the Guadiamar Green Corridor was created to connect two huge natural areas, Doñ ana National Park and the Sierra Morena. Within this corridor, the reptile community remained dramatically impoverished, probably because of elimination of all natural refuges during the soil restoration program.To test this hypothesis, we set an array of artificial refuges (logs) in a large experimental plot. During the 5 years of the experiment (2002)(2003)(2004)(2005)(2006), the area managed with artificial refuges exhibited a better and faster recovery of the reptile community in species richness and individual abundance than did the control area with no artificial refuges. Moreover, reptile colonization of the Guadiamar Green Corridor was transverse rather than lineal-that is, it did not act as a corridor for reptiles, at least in the first stages of colonization. This suggests that landscape restoration programs should not neglect refuge availability, a limiting resource for reptile species.

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SummaryBonelli's Eagle Hieraaetus fasciatus and Golden Eagle Aquila chrysaetos are two declining species, in which floaters tend to be located outside of breeding territories during the dispersal period, in so-called settlement areas. We studied settlement areas for both these long-lived raptors in the southern Iberian Peninsula, to gain a better understanding of the ecological requirements of the eagles during their long pre-adult stage, a period accounting for around 80% of the species' mortality. Eagle abundance was calculated by road censuses, and habitat characteristics of settlement and non-settlement areas compared by General Discriminant Analysis (GDA) and Logistic Regression (LR). The best model of GDA and LR incorporated the abundance of main prey for eagles (rabbits, partridges) and orchard surface area, and explained 100% of eagle presence; the best model selected by GDA also included habitat heterogeneity. Both eagles tended to share settlement areas in the southern Iberian Peninsula and, when they did not, the mean annual temperature and slope appeared to explain the segregation between the two species. Management measures for the conservation of both threatened species during the dispersal period should be focused on identifying settlement areas, maintaining high prey densities and maximum habitat heterogeneity. ResumenEl Á guila Perdicera Hieraaetus fasciatus y el Á guila Real Aquila chrysaetos son dos especies en declive, cuyos inmaduros tienden a localizarse fuera de los territorios de los reproductores durante el período de dispersió n, en zonas conocidas como áreas de asentamiento. Hemos estudiado estas áreas para ambas rapaces en el sur de la Península Ibérica, con el fin de comprender mejor las necesidades ecoló gicas durante su prolongada etapa preadulta, un periodo en el que en torno al 80% de los individuos mueren. Mediante censos en carriles se calculó la abundancia de las dos águilas, y se midieron las características del hábitat en áreas de asentamiento y no asentamiento comparándose mediante un Análisis Discriminante General (ADG) y una Regresió n Logística (RL). El mejor modelo del ADG y RL incluye la abundancia de las presas principales de las águilas (conejos, perdices) y el porcentaje de cultivos arbó reos, explicando el 100% de la presencia de las águilas, y el mejor modelo seleccionado por el ADG también incluyó la heterogeneidad de hábitats. Ambas águilas tendieron a compartir las zonas de asentamiento en el sur de la Península Ibérica y, cuando esto no ocurrió , la temperatura media anual y la pendiente parecían explicar la segregació n entre las dos especies. Las medidas de gestión para la conservación de ambas especies amenazadas durante el periodo de dispersión deben centrarse en la identificació n de las áreas de asentamiento, el mantenimiento de altas densidades de presas y de alta heterogeneidad de hábitats en estas áreas.