50 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



Edwin Beaupre (1922) found, in Ontario, a set of this falcon's eggs 

 in a very unusual location: "They were laid among ferns close to 

 some silver birch saplings on the open ground on the top of a cliff." 



The islands off the coasts of California and Lower California offer 

 ideal nesting sites for duck hawks, where they are free from preda- 

 tory animals and where they find abundant food among the sea 

 birds. Here their nests are often easily accessible to the collector, in 

 some natural cavity or on some small shelf on a low cliff sometimes 

 only 10 or 20 feet high. 



Along the coasts of Labrador and Ungava the duck hawks nest on 

 the islands or on cliffs on the mainland, usually near breeding colonies 

 of gulls, eiders, or other sea birds. A pair had a nest on an island 

 we visited near Nain, in the midst of a large colony of glaucous gulls 

 and black guillemots. Lucien M. Turner says, in his notes from Fort 

 Chimo, that there is scarcely an island near the sea-bird colonies that 

 does not have one or more pairs of these falcons nesting on or near it. 



Eggs. — The duck hawk lays ordinarily three or four eggs, occa- 

 sionally five and very rarely six or even seven. In shape they vary 

 from short-ovate or ovate to oval, or even elliptical-oval. The shell 

 is smooth or finely granulated. The eggs are richly and handsomely 

 colored; the ground color varies from creamy white to pale pink, but 

 it is almost always nearly, or wholly, concealed by small blotches, 

 spots, or fine dots of brilliant rich browns or reds, which are some- 

 times concentrated at one end. The colors most often seen are 

 "Morocco red", "mahogany red", "brick red", "Kaiser brown", 

 "hazel", "russet", or "tawny." Some light-colored eggs are "pale 

 salmon color", finely speckled with "Congo pink", overlaid with a 

 few scattering blotches of "cinnamon-rufous"; rarely one has faint 

 underlying blotches of "pallid purple-drab." Often there is a solid 

 wash of color at one end, or over the whole egg, with darker markings 

 over it. The measurements of 61 eggs, in the United States National 

 Museum, average 52 by 41 millimeters; the eggs showing the four 

 extremes measure 57 by 43, 56.5 by 43.5, and 48.5 by 38.5 millimeters. 



Young. — The period of incubation has been said to be 28 days, but 

 Mr. Hagar has definitely determined that it varies from 33 to 35 days. 

 He says, in his notes: "The two sexes change places rather frequently 

 from the time the first egg is laid until incubation begins, if the 

 weather is cold or stormy; once incubation has started, the female 

 sits very closely for the first two weeks or so, leaving the nest only 

 long enough to receive birds brought in by the male. She is most 

 likely to leave the nest late in the afternoon. The last half of the 

 incubation period the male performs rather more of the incubation, 

 usually taking short turns in mid morning and late afternoon, while 

 the female goes hunting." 



