Long-term Trends of Persistent Organochlorine Pollutants, Occupancy and Reproductive Success in Peregrine Falcons (Falco peregrinus tundrius) Breeding Near Rankin Inlet, Nunavut, Canada.

—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 DDt (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. Reproduced with the permission of the Arctic Institute of North America from Arctic (2010) 63(4):442–450. FrANkE, A., M. sEttErINgtON, g. cOurt, AND D. bIrkhOlz. 2011. long-term trends of persistent organochlorine pollutants, occupancy and reproductive success in Peregrine Falcons (Falco peregrinus tundrius) breeding near rankin Inlet, Nunavut, canada. reproduced in r. t. Watson, t. J. WIDEsPrEAD DEclINE OF thE PErEgrINE FAlcON (Falco peregrinus) in North America was attributed to reproductive failure (Peakall 1976, cade et al. 1988) associated with the ubiquitous use of persistent organochlorine pollutants, in particular DDt (dichlorodiphenyl-trichloroethane) (hickey 1969, Fyfe et al. 1976, cade et al. 1988, ratcliffe 1993, cade and burnham 2003). Despite bans on the use of DDt imposed in canada in 1969 and in the united states in 1972 (kiff 1988), the Peregrine Falcon of continental North America (F. p. anatum) was extirpated over its range east of the rocky Mountains and south of the boreal forest by 1975 (Fyfe et al. 1976). however, the species has shown considerable recovery over the last two decades (Ambrose et al. 1988, rowell et al. 2003, cade and burnham 2003, banasch and holroyd 2004), in part due to the release of captive-bred birds. In 2006, the committee on the status of Endangered Wildlife in canada (cOsEWIc) downgraded the threat level for the continental sub-species F. p. anatum from “threatened” to “special concern” (cOsEWIc 2006), and the Peregrine Falcon, F. peregrinus, was removed from the united states list of endangered animals in 1999. the strong recovery of Peregrine Falcon populations in North America is assumed to have been fueled by two main factors: captive breeding with re-introduction and, just as important, a decline in persistent organochlorine residues in Peregrine Falcons and their prey species. remarkably, there exist relatively few studies of the toxicological status of North American Peregrine populations during this recovery era. court (1993) assessed the toxicology of Peregrine Falcons (F. p. anatum) breeding in Alberta, canada between 1968 and 1992, while court et al. (1990) and Johnstone et al. (1996) reported on the toxicology of the rankin Inlet population from 1982 to 1986 and 1990 to 1994, respectively. Jarman et al. (1994) reported on organochlorine compounds in the plasma of Peregrine Falcons nesting in greenland. More recently, henny et al. (1996, 2009) reported on trends of organochlorine contaminant levels in migrant Peregrine Falcons captured on Padre Island, texas, and Vorkamp et al. (2009) summarized long-term trends in residues found in nesting birds in greenland. the present study has two primary objectives. the first was to summarize the changes in blood plasma concentration of dichlorodiphenyl-dichloro-ethylene (DDE), a metabolite of DDt; polychlorinated biphenyls (Pcbs); and dieldrin in adult Peregrine Falcons captured on territory at rankin Inlet from 1982 to 2006. the second was to report on annual occupancy and nestling productivity of these birds from 1982 to 2009. We also present trends in average summer temperature and patterns of precipitation experienced at rankin Inlet over the same period.