Sitting at approximately 32 degrees north latitude, the Patagonia area lies at the verge of the American subtropics. Follow this imaginary line around the globe and you’ll wind up in such exotic locales as North Africa, Iran, and northern India – also subtropical regions.
As colder climates retreated north from our area, a host of more tropical species followed the warming trend into the Sky Islands region. Many of the most famous, as well as some of the most obscure, of our flora and fauna were originally inhabitants of tropical Mexico who gradually or not-so-gradually moved into our region in the last 8,000 years or so.
The first wave of tropical species likely could fly or at least hitch a ride, including birds and bats. Perhaps the first sojourners were visitors who veered off-course or were unable to colonize our region. Lesser long-nosed bats, for example, require tropical plants for their nectar and pollen. Thus, they need giant saguaro, other columnar cacti, and various agaves, which may not have made the northern move yet. What if one of these bats had recently feasted upon saguaro fruit in Mexico and defecated the seeds on a Sky Islands mountain slope. Voila! – instant tropics thanks to a combination of wings and hitchhiking seeds!
Such plausible ecological scenarios played out over thousands of years and continue to this very day – perhaps spurred on by our current climate change. Witness the first Arizona record of a clay-colored thrush in May of this year.
Whether chronicled by humans or not, tropical species from mammals to (especially) invertebrates, birds, and perhaps reptiles, amphibians, and fish dip their proverbial toes into Arizona. As to their actual staying power in our state, that depends upon a myriad of factors, such as habitat(s), weather at the time, as well as sheer luck.
Case in point: I have seen only two blackened bluewings, stunning tropical butterflies, in my life, both near Patagonia Lake and both winter visitors that were likely making cameo appearances with no hint of breeding potential.
As the searing months of June and July come into play, so too do many of our more common tropical species. Many of our succulents, the majority of which have tropical origins, bloom. The showy flowers of cacti often lure in tropical bee species, while various yuccas have evolved species-specific symbioses with their pollinating yucca moths.
If you want to witness a real tropical treat, then hang out at a flowering agave and enjoy the procession of both tropical and temperate pollinators. Such disparate species as tropical bats, several oriole species, bees, doves, ants, and hummingbirds are among the throngs drawn to the nectar feast at agaves.
June and July are prime time for many of our tropical reptiles. Soaring ambient temperatures equate to more amenable body temperatures for these sunning saurians. Gila monsters are on the prowl for a satisfying meal of quail eggs or baby mice, for example. Meanwhile, Sonoran spotted whiptails ply the hot ground for smaller invertebrate prey. As monsoonal moisture is pulled into the region, watch for increasing activity among our legion of rattlesnake species. While they can be found any month of the year, the onset of the monsoon really seems to bring them out of the woodwork.
This transitional period from dry to wet also sees many birds and amphibians – tropical and temperate alike – kick into breeding mode. Monsoon rains allow our hot temperatures to bring forth a profusion of life, much of it tropical in origin, supporting our high levels of biodiversity.
Hot to hotter. Desiccated to deluged. Temperate to tropical. Enjoy June and July!
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS LLC, their Nature Adventure & Conservation organization devoted to protecting and promoting the unique biodiversity of the Sky Islands region. RWWJ offers private birding & biodiversity tours. Visit: www.ravensnatureschool.org