Long-term trends of persistent organochlorine pollutants, occupancy and reproductive success in peregrine falcons (falco peregrinus tundrius) breeding near rankin inlet, Nunavut, Canada

Abstract

The historical decline of the peregrine falcon (Falco peregrinus) in North America was attributed mainly to reproductive failure associated with persistent organochlorine pollutants, in particular DD T (dichloro-diphenyl- trichloroethane). It is generally assumed that declining trends in pesticide loads will be accompanied by a corresponding increase in reproduction. In this study, we concurrently measured occupancy, reproductive performance, and pesticide loads of breeding-aged adults on territory near Rankin Inlet, Nunavut, from 1982 to 2009. Our findings indicate that reproductive success of peregrine falcons in our study population declined despite concomitant reductions in pesticide loads, and that on average, approximately three fewer territories were occupied annually from 2002 to 2009 than were occupied from 1982 to 1989. In addition, the average number of young to reach banding age annually from 2002 to 2009 was approximately half the number banded annually from 1982 to 1989. These results indicate that in recent years fewer pairs have attempted to breed; in addition, those that did breed successfully raised fewer young to banding age. In general, the pesticides examined in this study cannot mechanistically explain either the reduction in occupancy or the decline in reproductive performance. We suggest that the proximate effects of local weather patterns-ultimately associated, either directly or indirectly, with overall climate change-have the greatest potential to explain the altered demographic features of the Rankin Inlet population. © The Arctic Institute of North.