SAN LUCAS THRASHER 379 



Nesting.— 'M.Y. Bancroft (1930) says of the nesting habits of this 

 race: 



It builds about half its nests in or under mistletoe, therefore most often in 

 mesquite. It uses cholla frequently, the crotch of a cardon, or an arrow tree or 

 other thorny growth. The same pair may utilize, in successive seasons, three 

 or four types of sites. If in a scrub tree it may be anywhere from the heart to 

 the outer branch tips. It will on the average be perhaps ten feet above the 

 ground. 



The nests themselves are not very dissimilar, though those of the Vizcaino 

 Desert average somewhat lai'ger and they are more substantial than the others. 

 A good understructure of rather short and fine twigs holds a hemispherical cup. 

 This is thicker and deeper than that of the jays and is built of thread-like 

 rootlets. It is of the same material throughout, the only suggestion of a lining 

 being an occasional feather, or bit of lizard skin, or perhaps a pinch of cotton. 



Baird, Brewer, and Ridgway (1874) state that, according to Xantus, 

 "their nests were flat structures, having only a very slight depression 

 in or near their centre. They were about 5 inches in diameter, and 

 were very little more than a mere platform." 



Since the above was written, Mr. Bancroft has sent me the following 

 notes : "In choosing nesting sites in cholla the Mimidae, as a family, 

 display little individuality. They select healthy plants, apparently 

 to prevent their nests being destroyed by falling segments. They 

 usually, though by no means always, build in the lower half of the 

 bush and make a definite effort to get well inside. They are much 

 more interested in protection from the top and sides than from below. 

 I have noticed virtually no differences in the technique of cine7'eimi, 

 7eco7itei, and curvirostre. 



"The garambuUo is a globe-shaped echinocactus typically about 6 

 feet in diameter. It is composed of innumerable arms 2 or 3 inches 

 thick and spaced about twice that far apart. The thrasher we are 

 discussing usually places its nest halfway from the center to the 

 outside of the bush, and about two-thirds the distance from the bottom 

 to the top. There may be easily six or eight old nests in one plant. 

 It is not at all unusual to find the nest of a wood rat and an occupied 

 thrasher nest in the same garambullo. The inference, of course, is that 

 the rats do not disturb the birds. 



"In an ironwood the nest is apt to be 5 or 6 feet above ground, 

 according to the thickness of the foliage, and placed directly against 

 the trunk. In mesquite it usually is placed in the ubiquitous mistletoe 

 and may be easily 15 or 20 feet high. 



"It is an old trick, in hunting for the eggs of any thrasher, to follow 

 up the lead given by old nests. Where these are found a search in 

 the vicinity will often reveal the new one. If I should discover an old 

 cinereum nest in, for instance, a cholla, I probably will locate other 

 old nests in the immediate vicinity, also in cholla. If so, it would be 

 a waste of time to look through the garambullo or any other growths 



