July, 1 V 1 5 
WOODPECKERS OF THE ARIZONA LOWLANDS 
157 
ing but the difference was too slight to be sure of in measuring. Of eighteen 
holes measured, the average diameter was 1.95 inches; the largest was 2.25 
inches and the smallest 1.87 inches. The deepest hole was 16 inches, with the 
entrance 2 inches in diameter. The shallowest one was 9 inches, with entrance 
a little less than 2 inches in 
diameter. The average depth 
of holes measured was a lit- 
tle more than 12 inches. 
Many of the holes were not 
exactly circular, there being 
a difference of from % to 
nearly V 2 inch between the 
long and the short diameter 
if it be allowable to use the 
term in that way. Usually 
the nest hole runs straight in 
for a short distance before 
turning downward, the dis- 
tance seemingly depending 
on the texture of the wood. 
In one case the hole went 
straight back for nine inches 
before turning downward. It 
was in a big cottonwood 
stump, and the bird excavat- 
ed horizontally until decayed 
wood was reached, when the 
hole turned downward. This 
was an extreme case, as the 
depth horizontally is usually 
about three inches. In the 
giant cactus it varies accord- 
ing to the diameter of the 
trunk, the smaller the trunk 
the less distance before turn- 
ing downward. The softness 
of the material is not a fac- 
tor as it is the same in small 
and large trunks. In only 
two cases have T found nest 
holes that penetrated through 
the ribs of the cactus into 
the inner pith. In both cases 
the trunk was too small to 
furnish room for the nest be- 
tween the outside and the - 
ribs. The holes are dug in the soft pulp of the cactus, and the raw surface be- 
comes calloused, as it were, forming a tough woody lining to the hole, which 
persists when the rest of the pulp decays. In this way the nest holes may be 
found intact, the hole being outlined by the hardened pulp, while the surround- 
... mmm 
Fig. 57. Nest cavity of Gila Woodpecker, 
from Giant Cactus trunk, showing the 
HARDENED LINING REMOVED FROM THE PULPY 
STALK. 
