SAX FRANCISCO BROTVT«f TOWHEE 609 



to be between 4 and 12 feet. The nest is placed in the densest part 

 of the foliage and is usually supported by several branches. J. 

 Grinnell and M. W. Wythe (1927) report nests being found from mid- 

 April to the first week in September, situated well above ground in 

 thick bushes or low trees. 



A series of unusual nest sites have been reported. J. Mailliard 

 (1936) reports a nest built a few inches underneath an apple. When 

 the apple finally fell, it did not break any of the four-egg clutch, 

 but the nest was deserted. J. McB. Robertson (1931) reports that 

 towhees will nest in eucalyptus in accumulations of bark not too far 

 from the ground. It is one of the few species to respond to this exotic 

 tree, so plentiful in California. Brown towhees C. D. Scott (1920) 

 kept in captivity nested on the ground two successive years. W. M. 

 Pierce (1915) found a pair of brown towhees nesting in a berry basket 

 10 feet inside a barn door, but they deserted it midway in incubation. 



Ejgs. — The measurements of 40 eggs average 24.9 by 18.3 

 millimeters; the eggs showing the four extremes measm-e 26.4 by 18.3, 

 25.9 by 19.7, 20.9 by 18.0, and 25.7 by 17.5 millimeters. 



Plumages. — John Davis (1951) has the following to say about the 

 molts and plumages of the brown towhee: 



The only molt of real significance in the brown towhee is the fall molt. At this 

 time adults undergo complete feather replacement. Birds undergoing the post- 

 juvenal (first fall) molt retain the primaries and secondaries, and usually the 

 rectrices. This molt pattern offers plumage characters that may be used to 

 separate first-year birds from second-year or older birds. In fresh fall plumage 

 the primaries of first-3'ear (= immature) birds are dull brown and the margins of 

 these feathers are finely erose because of wear. The primaries of second-year and 

 older birds (= adults) at this time are glossy and nearly black and the margins of 

 these feathers are entire. The rectrices of immature birds have pointed 

 tips * * * and show signs of wear. The rectrices of adults are obtuse at the 

 tip * * * and are glossy and unworn. Since rectrices are often replaced in the 

 post-juvenal molt, the amount of wear on the primaries offers the most reliable 

 criterion for judging age. 



The period of time over which these criteria may be used depends entirely on 

 the amount of wear to which the plumage of the individual is subjected. As the 

 adult primaries become worn they take on the dull brown color and erose margins 

 of the immature primaries. As the tips of the adult rectrices become worn they 

 become so ragged that it is impossible to distinguish them from the rectrices of 

 immatures. A few individuals may lose the characters of their age group as early 

 as December; others may retain them as late as June. Age determination of most 

 individuals becomes impossible by the middle of February. Occasional immatures 

 are encountered which retain a few of the juvenal upper tail coverts. This has 

 enabled the determination of age of some specimens that were otherwise so worn 

 that the usual criteria were of no use. 



The plumage of brown towhees is especially subject to wear. The abrasion of 

 feathers causes a noticeable paling over the entire plumage. This paHng is most 

 pronounced on the coloration of the throat, since the color of this region is re- 

 stricted to the terminal two-thirds of the throat feathers. As the colored portions 



