Sept., 1922 CACTUS WRENS’ NESTS IN SOUTHERN ARIZONA 165 
dendron californicum) which in many eases partially or wholly concealed them. 
One nest lay on a level branch covered by an unusual horizontal growth of mis- 
tletoe and showed only as a darkened mass inside, but most of them were in 
round ball-like masses of mistletoe, commonly at the ends of branches in ter- 
minal mistletoe rosettes, frequently so dense that it was impossible to obtain 
nest statistics or photographs. One of the nests without mistletoe protection 
was built under an umbrella-like mass of foliage. 
NEST CONSTRUCTION 
In form, the Cactus Wren’s nest suggests a retort, having a large globu- 
lar chamber about six inches in diameter approached through a long passage- 
way or entrance, the whole normally about twelve inches in length, the mouth 
of the entrance being about three inches above the base of the globular cham- 
ber. This nest chamber in course of years becomes a thick felted mass of gray, 
weathered plant fibers so hard that saucer-like sections sometimes crack off 
from the back, showing the solid, sodden bottom of the nest. The entrance, on 
the contrary, is made of long straw-like plant stems which may easily get 
blown about and so often need replenishing. 
When the old nests are repaired and ready for winter use these new 
straw-colored entrances often afford a striking contrast to the old gray globes, 
although occasionally the new material is lavishly distributed over the whole 
top of the nest. One nest, found on March 21, looked new, only straw-colored 
material showing from the few possible points of observation; but it might 
easily have had merely a coating of fresh material. A mass of fuzzy plant 
material was outside the mouth. An old gray nest fragment which might have 
supphed foundation material was behind the nest. Besides replenishing the 
straw entrance, the wrens re-line for cold weather. In one instance fur, and 
in many instances the small gray body-feathers of the Gambel Quail. and 
sometimes well-marked feathers of other species of birds, were seen in the en- 
trances and about the mouths. One nest used for roosting purposes during 
the winter, when examined for egos on Anril 30. had its globular chamber 
so thickly lined with soft feathers that it suggested a feather bed. 
Considerable variation and adaptability were shown in the construction 
of the nests examined. Sometimes in the process of repair the angle of the 
entrance was changed. In one case. while the old nest faced east, the new 
entrance faced south by east, almost at right angles, presumably for better 
support for the mouth and larger twigs for perches at the mouth. The con- 
trast in angle was emphasized by the color difference, the old nest chamber 
(about seven inches long and sagged at base) being gray and weathered, while 
the new entrance (about six inches long) was straw colored. 
As it has been said. more than half the nests in other than cactus were 
built inside a round ball-like mass of mistletce and were supported by its in- 
numerable twiglets. The value of this support is realized when considerine 
the tendency of the hard outer shell of the globular chamber to crack off if 
unsupported. ji 
In one instance the mistletoe protection made the builders extra work, 
for the diameter of the mistletoe ball was so great that the hallway of the 
nest had to be abnormally extended to provide an exit for the family at the 
outer edge of the ball. When not built inside a mass of mistletoe the nest was 
variously supported—hy a crotch, by a horizontal branch and the trunk of 
