Status report - Peregrine falcons in Big Bend National Park and the Rio Grande Wild and Scenic River

This report summarizes the 1997 productivity of peregrine falcon (Falco peregrinus anatum) territories in Big Bend National Park and along the Rio Grande Wild and Scenic River. Goals of the monitoring program included documenting falcon presence, nesting chronology, and breeding success at each location. Early in the 1997 reproductive season, 11 territories were occupied by paired peregrine falcons. The reproductive season resulted in 17 peregrines successfully fledging from eight eyries. Three of the eleven territories failed to produce fledglings. By comparison, fourteen territories were occupied in 1996, producing six fledglings. Eleven territories failed that year. In 1995 fourteen occupied territories produced two fledglings with 13 territories failing. The reproductive rate this year is 1.5 young per active eyrie. This figure is above the 1.25 suggested necessary for population maintenance (Enderson, 1985). However, population-wide productivity rates could be significantly different if productivity in the Sierra del Carmen and Maderas del Carmen mountain ranges of adjacent Mexico were known.