18 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



In the Yosemite section, according to Grinnell and Storer (1924), 

 the slender-billed nuthatch "ordinarily makes use of abandoned wood- 

 pecker holes for nesting sites." They found two such nests ; the first 

 "was 9 feet above the ground in an old hole of the White-headed 

 Woodpecker in a broken off and barkless Jeffrey pine stump"; the 

 second nest was in another old hole of the same species of woodpecker, 

 and was 7 feet from the ground ; the interior of this hole had been 

 enlarged by the nuthatches to a diameter of over 5 inches, and was 

 filled to within 7^/^ inches of the top, with deer and chipmunk hair 

 and feathers from various birds. 



W. E. Griffee writes to me of a nest that he found near Portland, 

 Oreg.) that was in a natural cavity only 3i/^ feet up in a small ash tree. 

 "The bottom of the cavity, which was about 6 inches in diameter, had 

 a heavy layer of grass and moss, and on top of that at least 2 inches 

 of rodent fur and a few feathers." 



Incubation. — From the observations of the ornithologists quoted 

 above, it seems evident that the female alone performs the duties of 

 incubation and remains on the nest for long periods at a time. Refer- 

 ring to the second nest, mentioned above, Grinnell and Storer (1924) 

 write : 



The female was on tbe nest and as she refused to leave even during the hubbub 

 incident to enlarging the entrance, the observer had to lift her from the nest in 

 order to examine the eggs. She seemed to be in a sort of lethargy and did not 

 struggle until actually taken in hand. That the bird had not left the nest for 

 some time was evident from the quantity of excrement which vpas accumulated 

 in the cloaca. The condition of this female, the food supply which the male of 

 the first nest had been seen to take to his nest, and the further fact that only 

 males had been nbted abroad for some days previously, led to the belief that in this 

 species the female alone carries on the duties of incubation and that she remains 

 upon the nest continuously for a greater or less period of time, during which she 

 is fed by the male. 



Fred Evenden writes to me that he saw a male feed its mate in the 

 nest 18 times between 2 : 30 and 3 : 49 p. m. ; the female came out of the 

 hole only once and perched on a stub for a moment. 



Eggs. — The slender-billed nuthatch has been known to lay 5 to 9 

 eggs, but oftener 6 or 7, though sets of 8 are fairly common. The 

 eggs probably show all the variations common to the species, but what 

 few eggs I have seen have been sparingly marked with small dots. 

 The measurements of 40 eggs average 18.5 by 13.9 millimeters; the 

 eggs showing the four extremes measure 20.0 by 13.5, 17.3 by 15.0, and 

 16.5 by 12.2 millimeters. 



Behavior. — White-breasted nuthatches are not, as a rule, gregarious ; 

 they are almost always seen singly or in pairs. But a remarkable story 

 of communal roosting at night is told by Dr. G. V. Harvey (1902). 

 One winter evening he saw 29 of these nuthatches come singly to an 

 old dead yellow pine, alight upon a knot, and vanish into a large crack 



