Part of the research effort involved surveying Walnut Canyon National Monument, Saguaro National Park, and Tonto National Monument for Arizona black rattlesnakes. USGS biologists worked with park staff and volunteers of each park unit during the primary season the snakes were expected to be active, late March through early October. They survey teams systematically searched areas and recorded basic statistics for each rattlesnake encountered. These efforts resulted in the identification of a relatively small number of Arizona black rattlesnakes. For this reason, it was not possible for scientists to determine specific population numbers for individual park units. In terms of relative abundance, the research team estimated that the species was most abundant at the highest elevations in Saguaro National Park, less common in Walnut Canyon National Monument, and rare at the lower elevations in Tonto National Monument. Interestingly, the species appears to coexist with the Hopi rattlesnake (Crotalus virdis nuntius), a subspecies of the western rattlesnake, at Walnut Canyon National Monument.
More extensive research activities took place at Tonto National Monument because park managers there needed information about the movement patterns and behavior of Arizona black rattlesnakes, which was frequenting wash areas used by visitors. Adult Arizona black rattlesnakes captured in Tonto National Monument were implanted with radio transmitters. The transmitters allowed scientists to track the movement of individual snakes. This project was the first radio telemetry study of the species.
USGS research indicated that Tonto National Monument, which is located in the upper reaches of the Sonoran Desert, is apparently at the the lower elevation limit for the Arizona black rattlesnake, which tends to prefer moister and cooler habitats. Within the monument, the snakes made use of moist habitats and dense vegetation. Scientists were also able to determine that Arizona black rattlesnakes did not spend much time in developed areas like trail and visitor areas. The snakes are thought to travel through developed areas on their way to more natural areas that offer them more protection and denser cover.
USGS research also indicated that Arizona black rattlesnakes in the monument mate in late summer and fall, coinciding with summer rains. Scientists also witnessed a male snake coil in a tight circle completely on top of a female, a behavior known as "stacking", during courtship. This behavior had not previously been seen in Arizona black rattlesnakes. Another finding of interest is that female Arizona black rattlesnakes appear to produce four to five young. Scientists captured an adult female in May that was found to contain five ovulated eggs. The snake subsequently became pregnant and was presumed to have had four to five young in August. As is typical of other rattlesnake species, female Arizona black rattlesnakes appear to stay with their young until the young first shed their skins, approximately one or two weeks after birth.
The hibernation period for rattlesnakes in Tonto National Monument lasts from late October through March, which is approximately two months shorter than the hibernation period observed for the species near Flagstaff, Arizona. The hibernation sites used by the rattlesnakes observed in Tonto National Monument, however, were similar to those used by the Flagstaff-area populations and featured slopes formed by rocky debris.