Peregrine Falcon (Falco peregrinus) Science Article 4
[…]. The study area was Bizkaia, a small province of 2300 km2 located in the north of Spain. In this area we have monitored about 35-38 Peregrine territories since 1997. During this time we have studied the prey of Peregrines in the nests, recording 931 prey of 97 different species. Between September 2000 and August 2001 we spent 129 full days observing falcons, 150 h monitoring a radio-tagged adult female and 40 h monitoring another adult female. […].
Zuberogoitia, I., Irta, A. & Martinez, J. A., Ardeola 49(1), 2002, 103-104