Using recruitment age, territorial fidelity and dispersal as decisive tools in the conservation and management of peregrine falcon ( Falco peregrinus ) populations: the case of a healthy population in Northern Spain

Methods of evaluating population trends have recently received particular attention because of perceived declines in several species during the twentieth century. We have studied demographic traits of the peregrine falcon (Falco peregrinus) population in Bizkaia (Northern Spain) for 11 years. This species suffered a severe decline in the 1950s and 1960s and started to recover in the 1980s and 1990s, although the recovery trends differed between areas. In our study area the peregrine falcon density is one of the highest found in Spain. The frequency of juvenile breeders was 2.0%, the mean age at first breeding being 3.7 calendar years for males and 4.0 cy for females. The territorial fidelity was at least 3.4 years for males and 3.7 years for females. Females dispersed on average 80.5 km and males 51.8 km during their pre-breeding movements, whilst distance between birthplace and breeding territories was on average 108.5 km for females and 64.5 km for males. We studied the relationships between adult turnover, recruitment age, territorial fidelity and dispersal in a healthy population in order to establish population dynamics. A combination of these parameters, not just age at first breeding, could be used as a potential early warning signal indicating future changes, prompting their consequences to be evaluated. This approach could lead to the reclassification of the large-scale health of a population. Its utilization would allow resources to be directed into helping “ailing” subpopulations, detecting causes of decline, and developing adequate recovery strategies.