380 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



in the neighborhood. The particular pair of birds in which I am 

 interested have a choHa complex which they stubbornly maintain. 

 Similarly, if my old nests are in garambullo, it would be foolish to 

 work in cholla, or, if they were on a hillside, it would be useless to 

 scour the valley. But, until the first of the old nests is noticed, I 

 have little reason to prefer one form of vegetation over another. 



"Nearly all my thrasher sets have been taken either from cholla, 

 garambullo, or ironwood. I have found the bird nesting, however, 

 in flatleaf cactus, pitahaya, and mesquite, on the arm of a cardon, in 

 frutilla, and in other unusual sites. Individually the birds are very 

 consistent; racially quite the reverse." 



Eggs. — Mr. Bancroft (1930) writes: 



Nothing lias been published contrasting the breeding habits of the two forms 

 of San Lucas Thrasher, though a comparison should be of interest. The Mearns 

 San Lucas Thrasher (Toxostoma cinereum mearnsi) reaches the height of its 

 breeding season 6 weeks to 2 months earlier than does T. c. cinereum. That 

 means March and April for one and May and June for the other. They lay 

 either two or three eggs ; I have one record of four for each. The more northerly 

 bird lays three much more often than two ; the converse is true of the other 

 thrasher. The eggs themselves are not distinguishable. They resemble those 

 of the Bendire Thrasher (Toxostoma tendirei) so closely that identification is 

 possible only from averages of color and sizes. 



Baird, Brewer, and Eidgway (1874) say: "The ground color is 

 greenish-white, profusely marked with spots of mingled purple and 

 brown. In others the ground color is bluish-green. In some speci- 

 mens the spots are of a yellowish-brown, and in some the markings 

 are much lighter." 



The only three eggs that I have examined are ovate, somewhat 

 elongated, and have a very slight gloss. The bluish-white ground 

 color is more or less evenly covered with spots and blotches of pale 

 browns, pale "cinnamon-buff" or very pale "clay color," and with 

 shell spots of "pale ecru-drab." They are totally unlike the eggs 

 of other thrashers, except Bendire's, which they closely resemble; 

 this is not strange, as the two species are closely related. Other ob- 

 servers have noticed this resemblance and their resemblances to eggs 

 of the mockingbird. 



Mr. Bancroft (1930) gives the average measurements of 92 eggs as 

 27.3 by 19.5 millimeters; among the measurements of 39 other eggs 

 before me, those showing the four extremes measure 31.0 by 27.0, 

 23.9 by 18.8, and 26.7 by 18.0 millimeters. 



Plumages. — Ridgway (1907) describes the juvenal plumage as much 

 like that of the adult but "pileum, hindneck, and back light buffy 

 grayish brown (between broccoli brown and wood brown), passing 

 into cinnamon on rump and upper tail-coverts; middle and greater 

 wing-coverts tipped with cinnamon-buff, the tertials margined ter- 



