16 BULLETIN 195, UNITED STATES NATIONAL MUSEUM 



with the pearl-white eggs." He says that, ordinarily, "the material 

 that surrounds the eggs is a strange conglomerate; made up, in greater 

 part, of disintegrated pellets ejected by birds of prey or voided by 

 coyotes. It is most interesting to note ; that this material seems to be 

 irregularly added at all times after the first choice of the home. Mate- 

 rial is often brought to the nest as late as mid-incubation time." 



Frank C. Willard (1912) says that, in Arizona, "nine out of ten nests 

 are in oaks, the balance usually in pines though a sycamore or madrone 

 is occasionally selected. A natural cavity with a long narrow open- 

 ing is generally elected. The nest is a mass of assorted fur and hair 

 of various animals, skunk and squirrel fur, cow and deer hair pre- 

 dominating. I have also found rabbit fur and bear's hair in their 

 nests. Enough is used to completely fill the bottom of the cavity and 

 come up a little on the sides." He mentions a nest in a pine stub on 

 tlie summit of the main ridge of the Huachuca Mountains, altitude 

 8,450 feet, one in an oak near the summit, and a nest in a dead stub of a 

 sycamore in the bed of a canyon, altitude 5,200 feet. "One brood, only, 

 is raised m a season. The same nesting site is sometimes used year 

 after year, though vermin in the nest frequently cause them to select 

 a new location the next season." The only nest that we found, while 

 I was with him, was 18 feet from the ground in a big blackjack oak, at 

 an elevation of about 7,000 feet in the Huachucas ; it was in a natural 

 cavity in which the base of a limb had not entirely rotted out; the 

 bird had entered through the cracks in the rotted wood and had a 

 fresh set of five eggs on May 12, 1922. The nest consisted of a great 

 mass of rabbit's fur, mixed with pieces of inner bark and bits of straw. 



E(/gs. — Mr. Willard has found as few as three heavily incubated 

 eggs and as many as six, but apparently the set most commonly con- 

 sists of five egg* These eggs are practically indistinguishable from 

 those of the eastern white-breasted nuthatch. What few eggs I have 

 seen are more lightly marked, but Mr. Peabody (1906) mentions some 

 heavily marked eggs ; I infer therefore that the eggs probably show 

 all the normal variations common to eggs of the species. The measure- 

 ments of 40 eggs average 18.9 by 14.2 millimeters; the eggs showing 

 the four extremes measures 21.1 by 14.3, 20.2 by 14.8, 17.3 by 14.2, and 

 18.5 by 13.2 millimeters. 



Behavior. — In most of its habits and traits the Rocky Mountain 

 nuthatch does not differ greatly from its eastern relative, though its 

 voice is thinner and weaker. It does not seem to gather into flocks, 

 as the pygmy nuthatch does, and is almost always seen singly or in 

 pairs, though Swarth (1904b) says that "a single one may occasionally 

 be seen in a flock of Pygmy Nuthatches or Chicadees." The members 

 of the pair are much devoted to each other ; the male feeds the female 

 on the nest ; and the pair travel about together in winter, keeping in 

 touch with each other with their quaint calls. 



