Peregrine Falcon Monitoring in Central Alberta, 2003
Author(s)
Dan Sturgess, Rob Corrigan
Summary
Previous to the 1950s, peregrine falcons (Falco peregrinus anatum) nested on cliffs along many Alberta rivers. Indicriminate use of the pesticide DDT in the 1950s and 1960s caused a worldwide decline in populations and the near extirpation of peregrines in Alberta. As a result, peregrines were listed as endangered in Alberta and Canada in 1971. Intensive management and the ban on the use of DDT in many countries have facilitated the recovery of peregrine populations, including those in Alberta.
This document reports the results of summer monitoring of 12 peregrine falcon nest sites in central Alberta between 2000 and 2003. Of the 12 nest sites, seven were located on cliffs in the North Saskatchewan River valley, two on power generation stations, and one within the municipal limits of the city of Red Deer. All 12 sites were visited in 2003 to: i) determine nest site/territory occupancy, ii) quantify breeding success and productivity of nesting pairs, and iii) provide an opportunity to band young-of-the-year peregrine falcons.
Peregrine falcons were obstructed at 10 of the 12 monitored sites in central Alberta, with nine breeding pairs producing clutches. Unoccupied territories were located at the Silent Springs and Rocky Mountain House sites. Seven successful pairs produced 19 fledged young while two pairs failed to produce any chicks of fledging age.
Data from annual monitoring showed that peregrine falcons in Central Alberta decreased from a high of 10 breeding pairs in 2000 to eight in 2002 and 2003. While the production of 19 young in 2003 is considerably lower than that in 2000 (33 young), it represents the third highest production of young in the last 13 years. Reproductive success, measured as the number of young per territorial pair, was 2.11 in 2003, which is higher than the overall longer-term average of 1.63 over the 1991 to 2002 period.
Declines in peregrine falcon populations in central Alberta in 2002 and 2003 compared to 2002 to 2001 is noteworthy and suggests that populations should be monitored annually to determine if these observations reflect variance within an increasing population trend or an early indication of a declining trend. Continued monitoring of key central Alberta sites can provide information to prevent a future decline.