tic coastal beaches in October with mean daily 

 minimum July temperatures in eastern Arctic 

 Canada indicate that minimum temperature on 

 the breeding grounds will cause a 31.6% (1-bird) 

 change in numbers of migrant immature birds 

 identified along the Atlantic coast per party-day 

 (Ruos 1970). 



The Arctic peregrine is, in effect, reproduc- 

 tively isolated from the more southern taiga pop- 

 ulation by its gonad cycle. The entire courtship 

 cycle of tundrius and thus the factors regulating 

 pair bonding is at variance with more southern 

 breeding peregrines (Cade 1960; White 1968). 



Peregrines apparently become established 

 along the lower ColviUe river between 4 and 10 

 May, with peak arrivals after the middle of May. 

 Falcon arrival is synchronized with the arrival 

 of their chief prey species. The incubation pe- 

 riod probably averages about 29 days for each 

 egg. Since there are intervals of 2 days between 

 egg layings and incubation begins with laying of 

 the first egg in the Arctic, there may be as much 

 as a week's difference in the ages of the youngest 

 and oldest nestlings. On the Colville, there was 

 one instance of laying in the last week of May, 12 

 instances in the first week of June, and 6 instances 

 in the second week of June. The total range for 

 any given event in the breeding cycle is barely 

 more than 3 weeks. Since the total period of the 

 breeding cycle from laying to the beginning of 

 independent existence of the young is not less 

 than 95 days in Arctic, peregrines must begin to 

 lay eggs not later than the third week in June to 

 ensure successful rearing of young before the 

 food is gone. The average clutch of Arctic birds is 

 3 eggs (54 samples), whereas the mean for the 

 U.S. is 3.74 (299 samples)showing a decreasing 

 size of clutch northward. Average fledging success 

 on the Colville River, Alaska was 1 .4 young per 

 nest. Predators on eggs and young, in addition to 

 man, are a negligible factor in the Arctic. Fairly 

 certain predators are the timber wolf, red fox, 

 arctic ground squirrel, and golden eagle (Cade 

 1960). 



Preincubation or courtship behavior divided 

 into 8 parts: (1) attraction of mates to each other, 

 (2) mutual roosting on cliffs, (3) cooperative 

 hunting excursions, (4) courtship flights, (5) 

 "familiarities" on cliff, (6) courtship feeding, (7) 

 copulation, (8) nest scraping. Females are dom- 

 inant over males and successful mating depends 



on the males' ability to adjust to that situation. In- 

 cubation and brooding is done mostly by the fe- 

 male, who sits more closely than females in more 

 southern latitudes. Food is brought by the male, 

 and even during the early fledging period, the 

 male continues to transfer food to the female for 

 feeding young. When young are about 3 weeks 

 old, the female begins to hunt actively again 

 (Cade 1960). Peregrines are definitely territorial 

 during the breeding season and defense of terri- 

 tory, which is roughly 3.22 km in diameter, has a 

 graded intensity from less intense at the outer 

 limits, where defense is only over food, to most 

 intense near the nesting cliff, which is always de- 

 fended against all other predatory birds, although 

 rough-legged hawks are sometimes allowed to nest 

 on the same cliffs within 100 yards (Cade 1960). 



First-year falcons not engaged in breeding 

 may pass their first summer within or at the peri- 

 phery of their breeding range, but are not obvious 

 because they are not associated with nesting sites. 

 In 1967 one first-year female was seen on the 

 Colville River (White 1969). 



Tradition is important in the occupancy of a 

 particular cliff. Once vacant, it may take a long 

 time for another pair to reoccupy it and establish 

 a new tradition. New occupancy is probably the 

 result of population pressure as well as attractive- 

 ness of the site (Cade 1960). 



MANAGEMENT AND CONSERVATION 



The most important actions that might be 

 taken in behalf of the Arctic peregrine would 

 probably be to designate for special protection 

 against land-use exploitation the areas where eyries 

 are concentrated in Arctic Alaska, Canada, and 

 western Greenland; as well as major migration 

 concentration areas along the Atlantic and Gulf 

 coasts and the shores of the western Great Lakes; 

 and to conduct an intensive educational and law- 

 enforcement program to reduce the use of chlor- 

 inated hydrocarbon pesticides in areas along the 

 major migration pathways and wintering grounds 

 in the eastern United States, West Indies, and 

 Central and South American countries. 



AUTHORITIES 



Thomas J. Cade 

 Laboratory of Ornithology 

 Cornell University 

 Ithaca, New York 14850 



