GILA WOODPECKER 251 



that were used by the larger species, as this woodpecker is fairly 

 common in the same region and nests regularly in the saguaros. 

 These old holes make ideal nesting sites, for the sap of the cactus 

 hardens around the excavations, making them fairly permanent nest- 

 ing boxes ; I have seen these gourd-shaped pockets still persisting in 

 fallen saguaros, where the pulp had all rotted away, leaving only the 

 skeleton ribs of the dead giant. 



Nesting. — ^While collecting with the late Frank C. Willard in 

 southern Arizona in 1922, we examined seven occupied nests of the 

 Gila woodpecker. The first of these was found on May 17, at Fair- 

 bank, in the valley of the San Pedro River; the nest was a cavity 

 15 inches deep in a dead branch of a cottonwood, 15 feet above 

 ground. Five days. May 19 to 23, were spent in Pima County, in 

 the vicinity of Tucson, between the mesquite forest in the valley of 

 the Santa Cruz River and the southern end of the Santa Catalina 

 Mountains. Two nests were found in the mesquite forest on May 19, 

 both in mesquite trees, one 20 and one 25 feet from the ground ; one 

 contained only a single fresh egg and the other held a brood of 

 young. We had an interesting experience here the next day. While 

 crossing the forest, I saw a Gila woodpecker fly out from what I 

 supposed was its nesting hole, about 15 feet up in a mesquite stub; 

 the bird made such a great fuss about it that I felt sure that we had 

 a set of woodpecker's eggs witliin easy reach, and I called Mr. 

 Willard to investigate it. He climbed the stub and chopped out the 

 hole, while the woodpecker was flying about, scolding us and show- 

 ing the greatest concern. But, much to our surprise, he pulled out an 

 elf owl and three unmistakable elf owl's eggs. I killed the owl and 

 shot the woodpecker, which still seemed much interested; and, on 

 skinning and sexing both specimens, I found that the woodpecker was 

 a male and the owl a female. We were naturally much puzzled to 

 figure out the relationship between the two birds and their interest 

 in the nest. But, since reading Mr. Gilman's remarks, quoted above, 

 that sometimes the woodpecker's tenants "do not even await the 

 pleasure of the excavators, but take forcible possession," it has oc- 

 curred to me that probably this was a case in point. The owl may 

 have appropriated the finished burrow of the woodpecker, and the 

 latter was trying to evict an unwelcome tenant. 



The remaining four nests found in this vicinity, and one found 

 by Mr. Willard on June 11, were all in saguaros on the desert mesa; 

 the heights from the ground varied from 16 to 20 feet ; and the cavi- 

 ties varied in depths from 15 to 20 inches ; there was one set of five 

 eggs, two nests held four and one three eggs; and in one nest were 

 two young and an addled Qgg. 



