NORTHERN CACTUS WREN 225 



the walls are so thick and the material so tightly matted together that 

 it would be difficult to make an opening into the nesting chamber with- 

 out considerable damage to the nest. The cavity is also usually more 

 or less filled with loose feathers. Curiosity as to the contents of cactus 

 wrens' nests should be tempered by due caution, as I have been informed 

 that one such investigation unfortunately resulted in the loss of an 

 intruder's eye as the startled bird darted suddenly through its only 

 means of exit. 



In spring, nesting usually begins in March or April, according to the 

 season. If the first brood is fledged successfully, in California a new 

 nest is built and a second brood brought off in June or thereabouts. 

 According to Mr. Scott (1888a), in Pinal and adjacent counties of 

 southern Arizona, the cactus wrens raise "at least two and sometimes 

 three broods. * * * The first eggs are laid in the Catalina region 

 as early as March 20, and the broods vary from three to five in number." 



^P'^*.— [Author's note : The usual set for the northern cactus wren 

 consists of four or five eggs, most commonly four ; but as few as three 

 may constitute a full set, and as many as six or even seven have been 

 found in a nest. The eggs are mostly ovate in shape, some being 

 slightly elongated or shortened. They are somewhat glossy. The 

 ground color varies from "salmon color" or "salmon-buff" to "seashell 

 pink," pinkish white, or rarely to nearly pure white. Usually the egg 

 is more or less evenly covered with fine dots or very small spots of 

 reddish browns, "rufous" to "ferruginous," sometimes nearly conceal- 

 ing the ground color; sometimes the markings are concentrated in a 

 ring about the larger end. Rarely an egg seems nearly immaculate, 

 and still more rarely an egg with a white ground is quite heavily 

 spotted or blotched with the above browns. The measurements of 50 

 eggs in the United States National Museum average 23.6 by 17.0 

 millimeters; the eggs showing the four extremes measure 26.4 by 

 15.2, 24.9 by 19.1, and 19.8 by 13.2 millimeters.] 



Young. — Because of the difficulty of discovering exactly what tran- 

 spires in the dark, feather-filled recesses of the nest, little information 

 is available as to the exact length of the incubation and fledging 

 periods. Both parents seem to share the nesting duties equally, 

 bringing insects and worms of various kinds to the young at frequent 

 intervals. Mrs. N. Edward Ayer (1937) gives the following inter- 

 esting account of the activities and difficulties of a family of cactus 

 wrens which occupied a nest in a rather unusual situation at Pomona, 

 Calif.: 



Toward the end of April 1937, a pair of Cactus Wrens built and occupied a 

 nest on a ledge under the corner of our tiled roof. On May 9th, a brolien egg 

 shell, creamy pink spotted with cinnamon, was found beneath the nest. For 

 the next 3 weeks the parents were kept busy feeding four hungry mouths, bread 

 crumbs from n nearby feeding station forming an important part of their diet. 



On the morning of May 29th, when we came down to breakfast, a loud chat- 



