504
BERNARD L. FONTANA
(Antilocarpa americana sonorensis) prefer the lower bajadas and intermontane plains. They share this preference with the coyote (Canis
latrans), antelope jackrabbit (Lepus alleni), blacktail jackrabbit (Lepus
calif ornicus), and bobcat (Lynx ruf us). The spotted skunk (Spilogale
putorius), badger (Taxidea taxus), various small rodents (Rodentia), including the kangaroo rat (Dipodomys spp.), the ringtail (Bassariscus
astutus yumanensis), and most of the lizards and snakes (Reptilia), avoid
the intense heat via their nocturnal habits or burrowing, or both (Simmons,
1965, p. 46). The desert cottontail (Sylvilagus auduboni), less common
than the hares (Lepus spp.), shares this life pattern. There are dozens
of other species of small mammals in western Pimeria Alta, and their
names and distributions are given by Cockrum (1960).
Bird life is reigned over by the golden eagle (Aquila chrysaetos). It
is known to nest high in the Sierra Pinta in southern Arizona (Phillips
et al., 1964, p. 24), and I have seen one soaring above the Growler Mountains near Charlie Bell Well. Various ducks and geese (Anatidae) are
seasonal migrants through the area, and a fair number of hawks (Accipitrinae) and the white-necked raven (Corvus cryptoleucus) are regular
residents. There are dozens of smaller species of birds which variously
breed in, migrate through, reside in, or occasionally visit the Arizona portion of western Pimeria Alta. Complete data are furnished by Phillips et
al (1964).
The bird story for northwestern Sonora is virtually the same except
that Sonoran Pimeria, unlike the Arizona portion, has a saltwater seacoast
on the head of the Gulf of California. Here there are innumerable shore
and sea birds, not to mention, of course, a rich fauna of fish, shellfish,
sea turtles, and ocean-going mammals. There are also gray wolves (Canis
lupus) in northwestern Sonora, and the mountain lion (Felis concolor)
is an occasional visitor here as he is also in southwestern Arizona.
/. Summary. In a very general way, what can be said of the arid west
of Pimeria Alta is that its eastern and southern portions are wetter and
cooler. Their valleys and mountains are higher and the bajadas are wider
and less steep. The vegetation and fauna are more varied and more
dense, and the possibilities of sustained life are greater than they are in the
west and north. Even so, the region taken as a whole is still among the
driest and hottest in North America.
2. Central Pimeria Alta
The central portion of Pimeria Alta is infinitely more hospitable to all
forms of life than the arid west. It lies almost entirely within the Arizona
Upland vegetational province of the Sonoran Desert; annual rainfall over
BERNARD L. FONTANA
(Antilocarpa americana sonorensis) prefer the lower bajadas and intermontane plains. They share this preference with the coyote (Canis
latrans), antelope jackrabbit (Lepus alleni), blacktail jackrabbit (Lepus
calif ornicus), and bobcat (Lynx ruf us). The spotted skunk (Spilogale
putorius), badger (Taxidea taxus), various small rodents (Rodentia), including the kangaroo rat (Dipodomys spp.), the ringtail (Bassariscus
astutus yumanensis), and most of the lizards and snakes (Reptilia), avoid
the intense heat via their nocturnal habits or burrowing, or both (Simmons,
1965, p. 46). The desert cottontail (Sylvilagus auduboni), less common
than the hares (Lepus spp.), shares this life pattern. There are dozens
of other species of small mammals in western Pimeria Alta, and their
names and distributions are given by Cockrum (1960).
Bird life is reigned over by the golden eagle (Aquila chrysaetos). It
is known to nest high in the Sierra Pinta in southern Arizona (Phillips
et al., 1964, p. 24), and I have seen one soaring above the Growler Mountains near Charlie Bell Well. Various ducks and geese (Anatidae) are
seasonal migrants through the area, and a fair number of hawks (Accipitrinae) and the white-necked raven (Corvus cryptoleucus) are regular
residents. There are dozens of smaller species of birds which variously
breed in, migrate through, reside in, or occasionally visit the Arizona portion of western Pimeria Alta. Complete data are furnished by Phillips et
al (1964).
The bird story for northwestern Sonora is virtually the same except
that Sonoran Pimeria, unlike the Arizona portion, has a saltwater seacoast
on the head of the Gulf of California. Here there are innumerable shore
and sea birds, not to mention, of course, a rich fauna of fish, shellfish,
sea turtles, and ocean-going mammals. There are also gray wolves (Canis
lupus) in northwestern Sonora, and the mountain lion (Felis concolor)
is an occasional visitor here as he is also in southwestern Arizona.
/. Summary. In a very general way, what can be said of the arid west
of Pimeria Alta is that its eastern and southern portions are wetter and
cooler. Their valleys and mountains are higher and the bajadas are wider
and less steep. The vegetation and fauna are more varied and more
dense, and the possibilities of sustained life are greater than they are in the
west and north. Even so, the region taken as a whole is still among the
driest and hottest in North America.
2. Central Pimeria Alta
The central portion of Pimeria Alta is infinitely more hospitable to all
forms of life than the arid west. It lies almost entirely within the Arizona
Upland vegetational province of the Sonoran Desert; annual rainfall over