in the total population of peregrines of northern 

 Canada. In general, up to that time, it had been 

 observed as a common breeding bird in an exten- 

 sive area (Fyfe 1969). 



In 1969, J. L. Ruos (pers. comm.) estimated 

 the annual harvest of tundra-breeding peregrines 

 (taken by falconers, mostly during migration) at 

 between 60 and 120 individuals, over 90% of 

 which were first-year birds. The effect of this 

 former harvest on the population is unknown, but 

 it has been prohibited under present migratory 

 bird regulations in the United States, where most 

 of it occurred. 



Earlier investigation of the Alaskan popula- 

 tion (Enderson et al. 1968; Cade et al. 1968) and 

 the Canadian population (Enderson and Berger 

 1968) indicated that members of this subspecies 

 were reproducing normally. However, Cade et al. 

 (1968) found that residues of organochlorines in 

 tissues and eggs appeared to be near the threshold 

 at which abnormal reproductive effects begin. 

 More recent studies by Cade and Fyfe (1970), 

 Berger et al. (1970), and Cade et al. (1971) indi- 

 cated that shell thinning was pronounced in pere- 

 grines from the northwest territories, the Ungava 

 region, and Alaska. The thinning approached or 

 exceeded 20%, the level at which reproductive 

 failures seem to begin. In addition, there was evi- 

 dence that F. p. tundrius populations of arctic 

 Canada and Alaska had declined suddenly. No 

 other reason for this decline than the effect of 

 pesticide poisoning on reproduction is suggested 

 (Cade and Fyfe 1970:235). 



PRIORITY INDEX 



10 



DESCRIPTION 



The Arctic peregrine falcon is a medium- 

 sized, pointed winged, swift flying bird of prey 

 with prominent black and white facial markings; 

 adults have slate gray back and white underparts 

 streaked and barred with black. Immatures are 

 brownish above and more heavily streaked below 

 than adults. They are similar to American pere- 

 grine falcons (anatum), but smaller and in all 

 plumages more lightly marked with paler browns 

 or bluish grays and less ventral rufous wash. Black 

 facial markings are more restricted (White 1968). 



Distinction between tundris and anatum in 

 adult plumage is best made by facial markings 



(width of black between eye and white auriculcir, 

 and width of malar stripe at base) and white fore- 

 head. The rufous basal portion of nape feathers, 

 which is whiter ventrally and somewhat paler dor- 

 sally, are also useful characters. Immature plum- 

 aged tundrius is distinguished from anatum by 

 facial characters, including a complete white 

 superciliary stripe, with darker stripe running 

 posterior to the eye usually present; also a median 

 pair of tail feathers conspiciously barred with 

 "vinaceous buff" (M. Ralph Browning ms. 1972). 

 Measurements (all in mm unless otherwise 

 indicated; values in parentheses are averages). - 

 Adult male (64 specimens): wing (chord) 292-330; 

 tail, 134-154 (140.5); tarsus 40-50 (44.3); bHl 

 without cere 15-20 (18.7); bUl with cere 22-25 

 (24.0); weight (12 breeding specimens), 550-647 

 (610.9) g. Adult female (62 specimens); wing 

 331-368 (351.8); tail 138-180 (167.8); tarsus 42- 

 57 (49.8); biU without cere 21-24 (22.7); bill with 

 cere 26-30 (27.8); weight (19 breeding specimens) 

 825-1094 g (952.9 g). Immature male (27 speci- 

 mens): wing 295-319 (311.1); tail 135-162 

 (151.8); tarsus 38-50 (44.0); bill without cere 17- 

 19 (18.3); bill with cere 22-25 (22.7); weight (4 

 specimens, fuUy fledged) 477-662 (570.0). Im- 

 mature female (30 specimens): wing 320-367 

 (349.6); tail, 155-189 (175.6); tarsus 44-(?)55 

 (49.1); bill without cere 19-24 (21.4); bill with 

 cere 23-28 (26.4); weight (3 specimens, fully 

 fledged) 844-925 g (889.0 g) (White 1968). 



RANGE 



F. p. tundrius breeds in tundra areas through- 

 out Arctic Alaska, Canada, and western Green- 

 land, from the northern tip of the Mackenzie Dis- 

 trict south and east across the Arctic tundra to 

 Hudson Bay, along the north coast of Ungava and 

 north into the Arctic islands as far as northern 

 Baffin Island and Melville Island; wesward as far 

 as Cape Prince of Wales, Alaska, and eastward to 

 the western coast of Greenland. The subspecies 

 intergrades morphologically with anatum in open 

 boreal forest or taiga areas of Alaska and Canada 

 (Fyfe 1969; White 1968). 



These peregrines migrate largely along the 

 Atlantic coast and to some extent through the in- 

 terior of the continent. The Atlantic coastal flight 

 includes some birds from western Greenland. 

 They winter north (sparingly) from at least Cape 

 Sable, Florida and Cameron Bayou Louisiana 



