This indicator tracks changes in an important raptor species, the peregrine falcon, a major predator on many species of birds and some small mammals. The indicator gives insights on how contaminants from other regions of the world affect a top predator species in NWT ecosystems.
Peregrine falcons are found on all continents of the world except Antarctica. Birds that nest in the NWT migrate to central and south America every winter. This raptor suffered a dramatic decline in numbers in the 1960-70s as bioaccumulation of pesticides (DDT/DDE) in females caused their eggshells to thin, substantially increasing egg failure. A ban on DDT in North America and a reduction of its use around the world, in addition to recovery efforts such as the re-introduction of falcons in southern Canada and the US, have resulted in a marked increase in nesting adults.
As a top predator on birds, the peregrine falcon is an excellent indicator of the overall chemical pollution present in all habitats used by the species and its prey. This indicator reports on the number of occupied nest sites and level of productivity measured during surveys performed regularly in two study areas in the NWT: the Mackenzie River study area in the Taiga Plains; and, the Daring Lake study area in the Southern Arctic.
In 2007, the peregrine falcon anatum/tundrius complex was re-assessed as a species of special concern by COSEWIC1. This is an improvement in status as the anatum type had been previously been assessed as threatened.
Information for this indicator is obtained from surveys performed by ENR and volunteers every five years as part of North American survey effort to measure the recovery of peregrine falcons across Canada and the US.
Two eco-types of peregrine falcon nest in the NWT2. The tundrius type is found on the tundra in the Southern and Northern Arctic ecozones.
The anatum type is found in forested ecosystems in the Taiga Plains3. Some peregrine falcon pairs also nest in the NWT Taiga Shield and Taiga Cordillera. There are 156 known peregrine falcon nesting sites on the tundra and at least 200 below the tree line (forested ecosystems). Not all sites are occupied in any given year and not all areas of the NWT have been surveyed for peregrine falcons so not all nesting sites are known.
Current view: status and trend
Mackenzie River – Taiga Plains
Number of peregrine falcon sites observed, occupied by at least one bird, and productive with at least one chick along the Mackenzie River. Number of young observed per productive site and per occupied site. Source: Peregrine falcon nest sites are surveyed using standard protocols. Surveys are conducted using helicopters and boat on the Mackenzie River study area.
Very few historical nesting sites were occupied in the 1970s, when the systematic survey of peregrine falcon on the Mackenzie River was initiated. By the mid-1980s, this population was increasing rapidly and reached the highest number of occupied sites recorded in 2005 and 2010. Productivity, measured by the number of young per occupied site in July, varies greatly from year to year. Annual productivity is influenced by weather and prey abundance, among other factors. Productivity, on average, has improved during the past 30 years as the effects of pesticides on falcon eggs diminished.
NWT populations of peregrine falcons have recovered from the drastic declines observed in the 1960-70s. However, many pesticides including DDT, are used in regions visited by peregrine falcons that nest in the NWT1. In addition, contaminants such as brominated flame retardants4 and persistent organic pollutants5 are found in increasing amounts in the tissues of top arctic predators, including peregrine falcons, with still unknown effects on their reproductive success and survival. Peregrine falcons are a prized bird of prey for falconry and are harvested1 in small but increasing numbers in Canada, Mexico and, soon, in the U.S. Peregrine falcons are also susceptible to disturbance. NWT is home to some of the highest densities of nesting peregrine falcons in North America. Some of these high-density areas are being investigated for future protection under the NWT Protected Areas Strategy.
Most populations of peregrine falcons nesting north of 60 have increased and seem to have recovered from the mid-century decline1. Recovery is slower and still underway in southeastern Canada and eastern US.
Find out more
- Information on peregrine falcons.
- Information on COSEWIC.
- Other surveys of peregrine falcons have been conducted in the NWT, including in Tuktut Nogait National Park and near the diamond mines southeast of Daring Lake.
Other focal points
- See SPECIES AT RISK for more information on status assessments and on COSEWIC.
- See CONTAMINANTS for indicators on the types and quantity of contaminants released to ecosystems in the NWT and elsewhere.
- More information on the history of status assessment of peregrine falcon can be found in the COSEWIC report in references below1. Raw data available on request from ENR.
Found an error or have a question? Contact the team at NWTSOER@gov.nt.ca.
Ref 1 - Cooper J. M., Beauchesne S. M.2007. Update COSEWIC Status Report on Peregrine Falcon Falconperegrinus in Canada, COSEWIC, Ottawa, ON.
Ref 2 - BROWN J. W. et al. 2007. Appraisal of the consequences of the DDT-induced bottleneck on the level and geographic distribution of neutral genetic variation in Canadian peregrine falcons, Falco peregrinus. Molecular Ecology 16:327-343.
Ref 3 - White C. M., Nancy J.Clum, Tom J.Cade, W.Grainger Hunt. 2002. Peregrine Falcon (Falco peregrinus) in A.Poole, Ed. The Birds of North America Online, Cornell Lab of Ornithology, Ithaca.
Ref 4 - de Wit C. A., Alaee M., Muir D. C. G. 2006. Levels and trends of brominated flame retardants in the Arctic. Chemosphere 64:209-233
Ref 5 - de Wit C. A., Fisk A. T., Hobbs K. E., Muir D. C. G. 2003. Effects of persistent organic pollutants (POPs) in Arctic wildlife.