Rivers are important in the falcon's environ- 

 ment; they create the nesting cliffs by erosion and 

 provide bathing facilities, especially on gravel 

 bars; rivers also provide habitat for shorebirds and 

 v^aterfowl for the falcon's food. Peregrines also 

 hunt extensively over the surrounding country, 

 particularly taking ptarmigan and longspurs (Cade 

 1960). 



They seldom nest on the cliffs along the Bering 

 Sea coast of mainland Alaska or in the mountains 

 above 800 m. A cliff of some sort is the most im- 

 portant feature of the nesting habitat (Cade 1960). 



FOOD AND FORAGING 



Food would not be a limiting factor in most 

 of northern Canada. Throughout that area, pas- 

 serines, shorebirds and waterfowl are abundant 

 in summer, with the exception of the Arctic 

 desert areas or relatively barren mountain tops on 

 Baffin Island (Fyfe 1969; Cade 1954). 



Bumham and Maddox (m Fyfe et al. 1976) 

 reported that four species of small passerine birds 

 made up over 90% of the food of peregrines in 

 western Greenland. J. N. Rice and R. B. Berry 

 (ms. 1970) also found that, with the exception of 

 a single ptarmigan, the peregrines nesting at 

 Ungava Bay in 1970 fed entirely on small pas- 

 serines, primarily horned larks, snow buntings, 

 and water pipits. Cade (1960), however, reported 

 that Arctic peregrines take a wide variety of avian 

 prey (waterfowl, shorebirds, and passerines), with 

 no single species predominating except possibly 

 ptarmigan. In his opinion, peregrines probably 

 feed heavily on lemmings during their cyclical 

 abundance, but that the availability of lemming 

 does not affect the peregrine population. 



SHELTER REQUIREMENTS 



None 



NESTING OR BEDDING 



In Arctic Alaska and Canada, nests are scrapes 

 in either earth or gravel, on bare grass, rocky cliffs, 

 cutbanks, dykes, boulders, or hummocks. Three 

 nests in old rough-legged hawks nests had eggs 

 laid on bare sticks with no soft material. Five 

 nests in old rough-legged hawk nests had eggs 

 and other plant material (Hohn 1955, McEwen 

 1957;Cade (1960); Fyfe 1969). 



Cliff nests are typical for the species and are 

 situated on a ledge or in a hole, often under a pro- 



tecting overhang. Nests on boulders and hum- 

 mocks have little or no protection from above 

 (Fyfe 1969). All nesting sites known in Alaska 

 were on cliffs on islands or along the coast or 

 river bluffs (Cade 1960). Of 57 eyries along the 

 Colville River, height of the nests above the river 

 ranged from 3.2 m to 96 m (average 35 m); the 

 distance below the brink of the cliff was to 90 

 (average 14) m. Fifteen of 57 eyries were located 

 on shale formations, 17 on sandstone or conglo- 

 merate, and 27 on earth or talus banks. Eleven 

 were in old rough-legged hawk nests. The brinks 

 of the cliffs are usually overgrown with dense 

 thickets of alder and willow scrub (Cade 1960). 

 All nests found by Burnham and Mattox (in Fyfe 

 et al. 1976) in western Greenland were located 

 on rocky cliffs varying in height from 25 to 120 

 m. All nests found in Alaska were on cliffs, mostly 

 along rivers (Cade 1960). 



RITUAL REQUIREMENTS 



The complex courtship and mating ritual is 

 described under Reproduction. A strong pair 

 bond is essential to the reproductive success of 

 the species (Cade 1960). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



Suitable nesting sites near an adequate food 

 supply and freedom from organochlorine chemi- 

 cals in the environment are the most critical re- 

 quirements. 



POPULATION NUMBERS AND TRENDS 



White (1969) said the number of breeding 

 adults on the Arctic Slope of Alaska seems to be 

 maintaining itself and there was no evidence of a 

 decrease in reproductive capacity. 



Population density was approximately one 

 pair per 52 km^ of suitable habitat in the Bathurst 

 Inlet area, Canada, and about one pair per 259 

 km^ in areas of limited nesting habitat. In esti- 

 mating 7,500 breeding pairs in northern Canada 

 (Fyfe 1969, J. H. Enderson and D. D. Berger in 

 Fyfe 1969), a sharp decline of nesting peregrines 

 was found along the Mackenzie River and at 

 Campbell Lake in 1966. 



Enderson (1969) calculated the mortality rate 

 of peregrines on the basis of band recovery (pre- 

 sumably mostly tundrius) as 70% for immatures 

 and an annual rate of 25% for adults. He assumed 



