88 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



Eggs. — Richardson's pigeon hawk lays from three to six eggs, 

 usually four or five. Mr. Randall's notes indicate that four is the 

 usual number, and Mr. Rowan evidently agrees with him; but Mr. 

 Brown took seven sets of five, one of six, and none of four. Most 

 of the eggs are indistinguishable from eggs of the eastern pigeon 

 hawk, but some are more lightly spotted, showing more ground color. 

 Mr. Rowan thinks that they are more like eggs of the hobby falcon 

 (Falco subbuteo) than like those of the merlin. The measurements of 

 48 eggs average 39.8 by 31.2 millimeters; the eggs showing the four 

 extremes measure 43.3 by 32, 42.7 by 32.5, 37 by 30.5, and 39.1 by 

 30 millimeters. 



Plumages. — The sequence of molts and plumages is apparently the 

 same as other pigeon hawks, but this race is easily distinguishable in 

 any plumage by its much paler coloration. The sexes are alike in 

 the immature plumage of the first year. This is similar to the 

 corresponding plumage of columbarius but much paler; the upper 

 parts are "hair brown" to "light drab", with "cinnamon" edgings 

 when fresh ; the under parts are paler and less heavily streaked than 

 in eastern birds. 



In the adult male the upper parts are pale, bluish gray, or "cinere- 

 ous", slightly darker on the upper back and crown, with narrow, 

 black shaft-streaks; the tail is "gull gray", or paler, tipped with 

 white, with a broad subterminal band and three interrupted bars of 

 black, the gray bands as wide as, or wider than, the black; the under 

 parts are white, or creamy white, deepening to "cinnamon-buff" on 

 the tibiae and paling to pure white on the chin and throat ; the throat 

 and tibiae are lightly, or not at all, streaked with black; the body 

 below is streaked with "buffy brown" or "snuff brown", with darker 

 shaft-streaks; the white bars on the remiges are wider than the dark 

 spaces. 



The adult female is similar to the male but has a distinct brownish 

 cast on the upper parts, much like the immature birds; and there are 

 usually spots of "light ochraceous-salmon" on the outer webs of the 

 wing quills. 



Females and immatures arc much like the corresponding plumages 

 of bendirei, but paler. 



Behavior.— We found this little falcon to bo quite rare in south- 

 western Saskatchewan. During two seasons there I succeeded in 

 collecting only one specimen and found no nest; my companions 

 collected another, and we saw two or three other birds supposed to 

 be this falcon. My bird was shy and was secured only by exercising 

 a little strategy. As we were driving along a prairie road we saw a 

 small hawk sitting on a fence post by the roadside; as we approached 

 he kept flying along ahead of us, alighting on the fence posts at fre- 

 quent intervals, but never allowing us to come within gunshot range. 



