May in the Sky Islands generally ushers in our first truly hot temperatures for the year. Most lingering spring wildflowers have vanished, any remaining wintering birds fly the coop, and high elevation flora and fauna start to kick into gear.
The soaring heat of this period heralds a decided uptick in activity among those plant and animal species that have bided their time through cooler conditions. They play a waiting game from late autumn through much of spring until balmy conditions once again call them forth.
Among species paying homage to the sun are some reptiles. Foremost are the whiptail lizards. Like all reptiles they are ectotherms—species reliant upon external temperatures for warming themselves. Too cold soon equates to too slow, which then spells death in the jaws or talons of a predator. Instead, these sun-lounging lizards wait for extreme temperatures, sunning themselves with legs splayed out to maximize heat gain.
Once warmed, it’s off to the races. Some species of whiptails can reach speeds of 17 MPH—often fast enough to elude their arch enemies, greater roadrunners and coachwhip snakes (among others).
While the whiptails usually keep themselves out of predatory reach via a combination of speed and camouflage, several other lizard species mostly forego the protective embrace of plants or rocks. They simply take their predators to the races. In particular, sun-heated zebra-tailed and greater earless lizards reach similar speeds to the whiptails yet are more effective at prolonged flat-out runs in open terrain. As a coup de grace these thermophilic or heat-loving lizards can wave their boldly black-and-white striped under-tails to signal that they’ve outrun their outstripped predators. If this doesn’t work, they simply dive and shimmy into the sand, disappearing altogether. Now you see me, now you don’t!
A slew of other reptiles join other invertebrates in their ongoing solar reverence. In May watch for butterflies sunning themselves—wings held horizontally, like painted solar panels. More heat equates to faster and more prolonged flights for purposes of predator evasion, territorial disputes and mating rights. Hotter means faster, hence safer, tougher and (ultimately) sexier.
Dragonflies use their wings to good effect when warming themselves directly in the sun. Like the butterflies, hotter translates to better overall fitness in life. The first winged creatures on the Earth appear to have been ancient dragonflies, whose proto-wings (i.e. still incapable of flight) may well have functioned solely as solar panels.
Birds are far more heat hardy than mammals, as evidenced by the glut of diurnal avian species and a dearth of day-active mammals. Watch for several species of local Sky Islands birds that sing even during the heat of the day. Bell’s vireos, Bewick’s wrens, and common ravens all seem to throw caution to the wind when it comes to the hottest parts of the day.
Nevertheless, they have their tricks. The smaller species generally hide under the cloak of cooler vegetation, while ravens sport reflective plumage that deflects much of the sun’s worst assaults.
Not to be outdone, some plant species have evolved to take advantage of May’s rising mercury. Some species with tropical affinities, such as yellow-trumpet and western coral bean, don’t leaf out or flower until prolonged spells of heat. They’re far too frost sensitive to emerge any sooner.
Then there are the many succulents that flower in May. Heat allows local bee species to thrive, which in turn furnishes pollinators for most of our species of cacti. Nectar feeding bats, returned from tropical Mexico this month, pollinate giant saguaro blossoms, another heat-driven ecological paradigm.
Heat drives many humans indoors during the swelter of May. If you decide to venture outside, keep an eye out for other “foolhardy” denizens, reveling in their sun-worshiping ways. This parched month brims with life—a kaleidoscope of species driven into a frenzy of activity by searing conditions.
Will you follow suit?
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 a wide variety of private, custom-made courses, birding & biodiversity tours. Visit: www.ravensnatureschool.org