164 THE CONDOR Vol. XXIV 
BREEDING SEASON 
When taking the nest census on January 15, a warm day that might have 
suggested nesting time, I heard an outburst of song and found four Cactus 
Wrens excitedly gathered about one tree which contained two old, broken- 
down nests. Two of the birds were singing with great animation, one on top 
of a bush spreading his tail. On January 29, another spring-lke day, Mr. Bai- 
ley found some of the wrens in the fifty-three acres ‘‘singing, chasing, and 
fighting.’’ Then, on February 15, what appeared a bit of courtship rivalry 
was witnessed. But on repeated visits the fifty-three acres was oppressively 
silent. On April 10 songs were heard suggesting that it was time to be watch- 
ing for real nest work, but the songs came from only two or three places. In 
one of these the day before, April 9, I had found a nest in the first stages of 
construction. Outside the fifty-three acres, in the bottom of a neighboring 
hot wash, on April 18, Mr. Bailey found a nest being built in a-cholla, both 
wrens gathering bills-full of grass and slender stems from the ground, and 
singing as they worked. Another cholla nest on the fifty-three acres had been 
begun before May 1, the week of our departure. But on April 30 about half 
of the accessible roosting nests were examined for sitting birds in the daytime, 
and nothing was discovered. 
In the adjoining Catalina region, Mr. W. E. D. Scott has said the first 
egos are laid as early as March 20; and on March 13, 1885, Mr. Herbert Brown 
of Tueson reported nesting well under way, the general nesting season, corre- 
lated with February rains, being unusually advanced. But as the winter of 
1920-21 was marked by severe drought, said to be the worst in thirty years, 
the breeding season as well as the vegetation may well have been retarded. 
Whether this was the case, or the fault was mine in failing to discover the 
breeding nests, the unfortunate fact remains that I was unable to correlate 
the summer and winter uses of the nests and had to leave unanswered many 
of the questions I had hoped to answer; among them—How many of the roost- 
ing nests were cock nests and how many of them would be used by the females 
for their eggs and young? 
NESTING SITES 
While many of the nests were grouped within a small radius, in some eases 
two or three being in the same tree, on the other hand, isolated nests were far 
from being the exception. Suitable bunches of mistletoe for building sites 
seemed one of the controlling factors. 
While the name Cactus Wren was justified in this locality as in others 
by the innumerable nests found in cholla cactus, here thorny trees and bushes 
especially catsclaw and zizyphus (Z. lycioides) or lote bush, were also used 
extensively, while mesquite and the dense shrubby hackberry or grenjeno were 
used occasionally for nesting sites. It was interesting to note that zizyphus 
bushes containing nests generally stood under mesquite trees, so getting dou- 
ble protection. The protection afforded by the armament of thorns was often 
so complete that it was impossible to reach a nest without cutting away the 
obstructing branches. Even that, however, did not always satisfy the nest 
makers, for such bulky, conspicuous nests need to be safeguarded in every way 
from hawks, owls, and other enemies. Thirty-five out of sixty-four nests ex- 
amined were not only protected by the entangling thorns of the surrounding 
branches but were built within clusters of the red-flowered mistletoe (Phora-— 
