Resumen de Long-term monitoring of a peregrine falcon population: size, breeding performance and nest-site characteristics

José Verdejo Bravo, Pascual López López

• Aims: We report a twenty-one year monitoring study of peregrine falcon Falco peregrinus brookei in the southwest of the Castellón province, a Mediterranean area of the East of Spain.

  Methods: We systematically monitored a small population occupying 5 - 10 different territories, from 1982 to 2002, over a 1500km2 study area.

  Results: A total of 120 breeding attempts were counted. The average breeding density in the study area was 0.41 ± 0.09 pairs / 100km2. The number of breeding pairs increased from 5 in 1982 to 9 in 2002. No differences in breeding performance were detected, neither between territories nor between years. Nests were placed in caves, cracks and holes, and peregrines even used nests originally built by corvids and large eagles for breeding. Territory alternation with other cliff-nesting birds was frequent, with cliffs occupied by common ravens, Eurasian kestrels and Bonelli's eagles.

  Conclusions: The population has doubled since the beginning of the monitoring, twenty-one years ago. Breeding parameters are of the highest reported in the world, although it could be caused by a low sample size. Notwithstanding, it suggests an optimum state of the population in the study area.