There is no doubt that southeastern Arizona is firmly planted within the greater southwestern U.S. Any casual observer can plainly see that we are rife with the fodder of the desert and other, associated arid lands. Cacti, rattlesnakes, thorny trees, ants, and other species emblematic of this parched quarter of our country abound.
Some of you, then, might be surprised to learn that you aren’t the only easterner whose range includes the Sky Islands of Arizona. A rather surprising number of both plant and animal species whose main range is the eastern and central U.S. also inhabit our region, adding a distinctive eastern flavor to our natural history.
Perhaps the most unmistakable species in this geographic spill-over is the desert box turtle. Upcoming monsoon season is prime time for viewing this reclusive reptile, as it spends most of the year hidden from our prying eyes. A range map of the species reveals that it barely enters Arizona in our southeastern-most counties, venturing no further west than southern Pima county. I’ve encountered just a handful of these fully terrestrial turtles during my long career in the Sky Islands – all during our monsoon season, which approximates the humidity and lushness of many eastern habitats. Its diet includes plants, various fungi (including extremely toxic species), invertebrates, and even carrion.
Another rare eastern-leaning reptile venturing into our area is the massasauga. This diminutive rattlesnake has a wide range in the eastern U.S. It is endangered in my native Pennsylvania, as well as in Arizona – the two states bookending its distribution. Here it can be found only in a few locations in Cochise County, where desert grasslands in the San Bernardino, San Simon, San Pedro, and Sulphur Springs valleys provide a tentative foothold. There, it consumes mostly reptiles and small mammals, with a spice of large centipedes. Its remote habitat and scarcity make it perhaps the most difficult rattler to encounter in a state abounding in them.
Arizona hosts a race of the eastern bluebird dubbed the “azure” bluebird, somewhat erroneously, as it is actually less blue than its eastern cousins. Its range swings up from the forested Sierra Madre in Mexico to marginally puncture our Arizona Sky Islands. Like all bluebirds, ours in Arizona nest in tree and other cavities, including nest boxes furnished by humans. Perhaps one day soon ornithologists who decide which birds are full species and which are not may assign the azure bluebird full species status. The same can be said of our local race of eastern meadowlark, “Lillian’s” meadowlark, which may soon attain full species distinction.
Among mammal species my favorite eastern spillover is the Virginia opossum, the only marsupial in the U..S. and sporting the most teeth of any North American mammal! Even as recently as the late 1990s the presence of this species in Arizona was somewhat in dispute. It seems to have pulled the same distributional “maneuver” as the eastern bluebird in that it penetrated our state via the Sierra Madre mountains. Since the ’90s it has become locally common to the point where it is a frequent member of our “flattened fauna” – i.e. roadkill. Drive slow at dusk and night you might just enjoy this odd mammal, while also sparing its life.
A much more subtle infiltrator from back east is the eastern cottontail. This familiar lagomorph inhabits higher elevations in our mountains, such as pine forests. Given that it is nearly a dead ringer for our desert cottontail from lower elevations, habitat differences are generally the best way to tell the two species apart. A cottontail in a desert or grassland here is likely to be a desert cottontail, while those inhabiting higher elevation environments over 6500’ are probably eastern cottontails.
My favorite easterner among our plants is gum bumelia, member of an otherwise almost exclusively tropical family that includes the tree which yields chicle – hence the gum moniker. While the main of its range encompasses the southeastern U.S., in the Sky Islands we host a disjunct population, primarily along arid riparian corridors at the base of mountains. There this small, solid tree sports wicked spine-tipped twigs, which serve to protect its dark purple fruit from mammals, as birds are the main seed dispersers. Walk through a gum bumelia forest, such as the one in Fort Bowie National Historic Site, in June and you’ll be treated to a suffusion of sweet aroma proffered by the tiny white flowers of this distinctive tree. Breathe it in deeply and appreciate it and the other eastern hints that help flavor our local haunts.
Vincent Pinto & his wife, Claudia Campos run RAVENS-WAY WILD JOURNEYS LLC, their Nature Adventure and Conservation organization – devoted to protecting and promoting the unique biodiversity of Sky Islands region. RWWJ offers a wide variety of private, custom-made courses including Birding and Biodiversity Tours. Visit: www.ravensnatureschool.com