34 LIFE HISTOEIES OP NORTH AMERICAN BIRDS. 



and distinct types of markings. These were likewise placed in two layers. 

 In the hot Gila River Valley in southern Arizona, nidification commences in 

 some seasons by the middle of March. 



Mr. John Swinburne informs me of finding a full set of eggs on March 19, 

 near Phoenix, in Maricopa County. In the vicinity of Tucson they lay some- 

 what later. The earliest date at which eggs of this species have been found 

 there, according to the observations of Mr. Brown, is April 4, usually about the 

 latter part of this month and the beginning of May, the nesting season con- 

 tinuing into August and sometimes even to September. 



The eggs of Gambel's Partridge are short ovate in form, and the ground 

 color varies from a dull white to a creamy white and pale buff color. The 

 eggs are spotted, clouded, and blotched, sometimes very heavily, with irregular 

 markings or blotches, and again with well-defined and rounded spots of dark 

 seal-brown and e"cru drab. Diffused over these blotches is found a peculiar pur- 

 plish or pinkish bloom, difficult to describe, resembling somewhat the rich 

 bloom found on blue grapes and various kinds of plums when first picked. 

 These markings, when touched by water or moisture of any kind, change 

 radically, becoming seal brown, or chestnut brown of different shades, accord- 

 ing to the variable amount of pigment on the shell of the egg. Carefully blown 

 specimens will retain this peculiar bloom for years, and some eggs collected by 

 me and now deposited in the U. S. National Museum, one of which is figured, 

 show this as plainly to-day as when they were first taken, fully eighteen years 

 ago. Eggs of Callipepla gambeli are, as a rule, more heavily spotted than those 

 of the two California Partridges, and the color of the markings in the majority 

 of specimens is decidedly different. The peculiar golden russet shade so often 

 present in the eggs of the latter is almost entirely wanting here, and is replaced 

 by darker and more bluish brown tints. 



The average measurement of ninety-seven specimens in the U. S. National 

 Museum collection is 31.5 by 24 millimetres, the largest egg of the series meas- 

 uring 34 by 26, the smallest 28.5 by 24 millimetres. The type specimens, No. 

 16480 (PL . 1, Fig. 11), selected from a set of ten eggs, taken June 14, 

 1872, and No. 21116, two eggs selected from a set of nineteen (PI. 1, Figs. 13 

 and 14), one showing the peculiar bloom before mentioned, and the other a 

 decided difference in the style of markings, taken June 20, 1872, near Rillitto 

 Creek, Arizona (Bendire collection), were found by the writer. No. 23938 (PL 

 1, Fig. 12), from a set of ten eggs, was taken by Mr. Herbert Brown at the 

 Laguna, near Tucson, Arizona, May 19, 1889. 



