64 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



Baird's Woodpecker, like several other species, is very fond of the ripe fig- 

 like fruit of the giant cactus, and I have met it more than once in Sahuarito 

 Pass, Arizona, eating it on the ground. It nests by preference in mesquite 

 trees, one of our hardest woods, and it must require a long time to chisel out a 

 nesting site in one of these trees. While it is true that the heart is usually more 

 or less decayed, the birds have first to work through an inch or two of solid 

 wood which is almost impervious to a sharp ax. Dr. James C. Merrill, United 

 States Army, reports Baird's Woodpecker as a common resident in the vicinity 

 of Fort Brown, Texas, and that he took several sets of its eggs there; it was also 

 met with by Mr. G. B. Sennett near Hidalgo, Texas, where a nest was found on 

 April 29 containing three young birds and a sterile egg. In Texas it has 

 also been found nesting in hackberry and china trees, as well as in telegraph 

 poles and fence posts. In southern New Mexico and Arizona it nests sometimes 

 in the flowering stems of the agave plant and also in yucca trees, and I have 

 found it nesting on Rillito Creek, Arizona, in a small dead willow sapling not 

 over 3J inches in diameter. The cavity was about 12 feet from the ground 

 and 10 inches in depth, and the entrance hole a trifle over 1 J inches in diameter. 

 This nest was found on June 8, 1872, and contained only two eggs, in which 

 incubation was about one-half advanced; the eggs laid on fine chips. The 

 nesting sites are placed at various distances from the ground, from 3 to 30, 

 usually from 6 to 14 feet. Dead branches of trees or partly decayed ones seem 

 to be preferred to live ones. 



From two to five eggs are laid to a set, usually four or five, and incubation, 

 in which both sexes assist, lasts about thirteen days. In the lower Rio Grande 

 Valley full sets of fresh eggs are sometimes found by the middle of April, but 

 throughout the greater part of its range^ not until the first week in May. I 

 believe one brood only is raised, as a rule, in a season; but, as fresh eggs are 

 sometimes found as late as July, it is probable that a second brood is occasion- 

 ally reared. The eggs of Baird's Woodpecker are glossy white in color, fine 

 grained, and mostly oval or elliptical oval in shape, varying occasionally to 

 elliptical ovate. 



The average measurement of fifty-seven specimens, mostly from the Ralph 

 collection and taken in the lower Rio Grande Valley, is 20.74 by 15.92 milli- 

 metres, or about 0.82 by 0.63 inch. The largest egg of the series measures 

 22.10 by 16.76 millimetres, or 0.87 by 0.66 inch; the smallest, 17.27 by 15.49 

 millimetres, or 0.68 by 0.61 inch, and a runt in the collection measures only 

 14.48 by 11.43 millimetres, or 0.57 by 0.45 inch. 



The type specimen, No. 20904 (not figured), from a set of four eggs, was 

 taken by Dr. James C. Merrill, United States Army, near Fort Brown, Texas, 

 on May 23, 1877. 



