Incubation requires 33 to 35 days. The two 

 sexes changed places on the nest frequently from 

 the time the first egg was laid until incubation be- 

 gan if the weather was cold or stormy. Incubation 

 for the first 2 weeks was by the female; last half 

 was mostly by male (Hager m Bent 1938; Herbert 

 and Herbert 1965; Porter and White 1973). There 

 was one brood per season unless the eggs were 

 taken; then a second or even a third clutch was 

 laid (Bent 1938). Sometimes the young fell from 

 the nesting shelf and were killed (Eaton 1910). 

 From 3 nests, the first young flew on the 33rd, 

 35th, and 33rd days (Hagar in Bent 1938). 



Some peregrines, when disturbed, may desert 

 their eggs and roost as much as 8.8 km away. Re- 

 nesting may or may not occur if the first attempt 

 is unsuccessful (Herbert and Herbert 1965;Hickey 

 1942). 



Northern peregrines (Yukon River, Alaska) 

 lay about 3 eggs; the number of chicks ranges 

 around 2.3 to 2.7 per eyrie (Cade 1960). Produc- 

 tion of "fledglings" per occupied eyrie on the up- 

 per Yukon River dropped from 1.80 at 15 sites in 

 1966 to 1.40 at 10 sites in 1967 to 0.93 at 15 

 sites in 1968. This decline was associated with re- 

 duced eggshell thickness there in the 1960's com- 

 pared with those prior to 1947 Qoseph Hickey in 

 lit 23 Dec. 1969). 



In Utah, egg laying began between 12 and 29 

 April (1943-1952). An average of 3.8 eggs (range 

 3-5) was laid per year during a 5-year period, and 

 2.4 (range 0-4) hatched (Porter and White 1973). 

 Natural mortality of first year peregrines is high. 

 Band returns indicate that 70% of fledglings die 

 in their first year (Enderson 1969). 



Predation on nestlings is by raccoons in Mas- 

 sachusetts (Hagar 1969), great horned owls in 

 New York (Cade ed 1975), and ring-tails in the 

 southwestern United States (White and Lloyd 

 1962). 



Reproductive success in Chihuahuan Desert 

 eyries of west Texas, despite significant egg shell 

 thinning of 17.9%, was 40% in 5 eyries in 1975 

 and 66.7% in 6 eyries in 1976. Reproductive suc- 

 cess was much better in mountain cliffs than in 

 river canyons (Johnson 1976). 



Of a northern Mexico high-country popula- 

 tion in the Sierra Madre Oriental of 6 pairs, 2 

 failed to nest successfully in 1976. The average 

 fledgling ratio was 2.0 per successful pair. Egg 

 shell thinning was 17.8% (Hitchcock 1976). 



In the Chihuahuan Desert region of northern 

 Mexico in 1976, 13 broods ranging in size from 1 

 to 4 young averaged 2.15 young per nest, compar- 

 ing favorably with pre-DDT eyries elsewhere. 

 Eyries on mountain cliffs were 78%) successful 

 and those in river canyons, 9% successful, indicat- 

 ing probable higher concentrations of pesticides 

 in river than in mountain environments. No dif- 

 ference was found in productivity of eyries of the 

 U.S. and Mexican sections of the Chihuahuan 

 Desert region. The rate of eggshell thinning was 

 greater in the northern and eastern sections than 

 in the southern part of the Chihuahuan Desert 

 region (Hunt 1976). 



A few peregrines produce young at 1 year of 

 age, but it is not certain that all are breeding at 

 age 2 (Hickey and Anderson in Hickey ed 1969). 

 If they do not normally breed until at least 2 years 

 of age, the average fledging rate, which is less than 

 one per pair per year, is insufficient to replace 

 normal adult losses (Rocky Mountain/South- 

 western Peregrine Falcon Recovery Team 1977). 



MANAGEMENT AND CONSERVATION 



This species is listed in Appendix I, Conserva- 

 tion for International Trade in Endangered Species 

 of Wild Fauna and Flora (Federal Register, Vol. 

 42, no. 35, 22 February 1977, p. 10476). 



Critical Habitat has been designated in five 

 areas in Sonoma, Lake, and Napa Counties Cali- 

 fornia (Federal Register, Vol. 42 no. 184, 22 

 September 1977, p. 47842). 



Four Peregrine Falcon Recovery Teams have 

 now been appointed by the U.S. Fish and Wildhfe 

 Service. The plan of action for saving the pere- 

 grine includes: (1) increased legal protection; (2) 

 preservation of natural habitat, especially nesting 

 sites, and evaluation of pesticide contamination; 

 (3) management of wild populations; (4) captive 

 propagation for "domestication" and for stocking 

 of vacated range; (5) educational and information 

 program to gain pubHc support; and (6) develop- 

 ing national and international cooperation and 

 coordination. Direct killing or molestation by 

 man is the least important threat, although it can 

 play a part and must be guarded against. There 

 are adequate laws, but law enforcement and the 

 public's attitude toward birds of prey should be 

 improved. Preservation of essential habitat, partic- 

 ularly irreplaceable historic falcon eyries, is the 

 most essential action (Cade 1974). It should be 



8 



