PLAIN TITMOUSE 



415 



in the A. D. DuBois collection was made of moss, grass, weed stems 

 and fibers, and was lined with a few feathers and rabbit fur. 



Eggs. — Six to eight eggs seem to be the commonest numbers laid 

 by the plain titmouse, with seven the prevailing number. Among 22 

 sets in the Museum of \'ertebrate Zoology, 14 were sets of seven. In 

 62 complete sets of eggs recorded by Dr. Price (1936), the numbers 

 ranged from three to nine; there were six eggs in 12 nests, seven eggs 

 in 17 nests, eight eggs in 14 nests, and nine eggs in 7 nests. Ernest 

 Adams (1898) records a set of 12 eggs, which might have been the 

 product of two females. 



The eggs are mostly ovate, sometimes elongated to elliptical-ovate, and 

 have practically no gloss. They are pure white and often entirely 

 unmarked, but usually some of the eggs in a set, and sometimes all of 

 then_i, are faintly marked with minute dots of very pale reddish brown. 

 These pale markings are sometimes evenly distributed over the entire 

 tgg and sometimes very sparingly scattered. Whole sets are some- 

 times pure, unmarked v/hite. 



The measurements of 40 eggs average 1.7.4 by 13.4 millimeters; the 

 eggs showing the four extremes measure 18.3 by 13.3, 18.4 by 14,2, 

 and 16.3 by 12.7 millimeters. 



Young. — Mrs. Wheelock (1904) gives the period of incubation as 14 

 days, which matches the figures given for other titmice. Dr. Price 

 (1936) was convinced, by his examination of "brood patches," that only 

 the female incubates; "only females ever v;ere captured incubating 

 the eggs." 



Mr. Adams (1898) says that the female is a very close sitter and has 

 to be removed by hand, clinpring tenaciously to the nest material and 

 often bringing some of it out with her ; even wlien thus forcibly removed, 

 she returns to the nest immediately; he had to put one in his pocket to 

 keep her cut of the nest v/hile he was removing the eggs. 



Both parents assist in feeding the young, and the large broods keep 

 diem quite busy. Mrs. Wheelock (1904) says: "lAy theory that most 

 voung birds are fed by regurgitation at first was confirmed in this case 

 bv the fact that, although I v/as witliin twelve feet of the nest whenever 

 either bird entered it during that first day, not once was any food visible 

 in the beak of either. After the fourth day the worms and insects carried 

 were frequently projecting on each side of the small beak, but up to that 

 time there had been none seen, though a careful watch was kept with 

 both opera glasses and naked e^-es." Apparently, the young birds that 

 she watched were about ready to leave the nest on the sixteenth day. 

 Evidently the young are driven away from the home territory as sooti 



