López-López, Pascual, García Ripollés, Clara, Urios, Vicente Population size, breeding performance and territory quality of Bonelli's Eagle Hieraaetus fasciatus in eastern Spain LÓPEZ-LÓPEZ, Pascual; GARCÍA-RIPOLLÉS, Clara; URIOS, Vicente. "Population size, breeding performance and territory quality of Bonelli's Eagle Hieraaetus fasciatus in eastern Spain". Bird Study. Vol. 54, No. 3 (2007). ISSN 0006-3657, pp. 335-342 URI: http://hdl.handle.net/10045/22689 DOI: 10.1080/00063650709461493 ISSN: 0006-3657 (Print) Abstract: Capsule. A five-year monitoring study is described of overall population stability and differential reproductive success in relation to habitat heterogeneity. Aims. To assess the effect of the altitude and orientation on laying date and breeding performance, and analyse the effect of territory quality as a likely factor that could be regulating the population. Methods. We monitored a population of 28–33 pairs, from 2002 to 2006, counting a total of 131 breeding attempts. Results. Territories located at lower altitude showed higher mean fecundity than those located at higher altitude. The mean laying date was February 18 ± 16 days. Laying date was positively correlated with nest altitude, the coastal pairs laying earlier than those in mountainous regions. Pairs located at lower altitudes showed higher mean fecundity than those located at higher altitudes. There was no preference in mean orientation either in breeding performance or in relationship to nest altitude. We did not find a difference in breeding performance between territories classed as being at high density and those classed as being at low density. Conclusion. The population has remained stable since the first national census was conducted 17 years ago. Our results could be explained in the light of the Habitat Heterogeneity Hypothesis. We suggest a differential reproductive success in relation to habitat heterogeneity. Keywords:Bonelli’s eagle, Hieraaetus fasciatus, Conservation, Population ecology, Raptors, Reproductive parameters, Spain British Trust for Ornithology info:eu-repo/semantics/article