We investigated the locations of Gila Woodpecker (Melanerpes uropygialis) nest sites in Organ Pipe Cactus National Monument, Arizona. A significantly greater proportion of saguaro cacti in arroyos had woodpecker holes than did those on hillsides, ridgetops or desert flats. Saguaros used for nest-hole excavation were taller and more likely to have branches than randomly chosen saguaros. Both active and inactive nest holes were nonrandomly oriented, with the mean vectors of orientation being in northwesterly directions. Variation in nest-hole orientation probably is not due to seasonal differences in excavations because the orientation of spring active (late March) nest holes was not significantly different from that of inactive holes. Some variation in nest-hole orientation is attributable to the structure of the saguaros.
© 1984 University Of California Press