Monsoon season has arrived, delivering a flush of green and a flourish of life, much to the relief of all of us suffering what is termed an “exceptional drought.” Hopefully August and September will continue to see ample rainfall and a concurrent spike in biodiversity.
With all of that life comes the inevitability of death. Plants put on growth, but then either die altogether, as in annual plants, or see portions of their structure perish. Various fauna adhere to the same pattern. Many invertebrates are short-lived, some even expiring post-mating. Meanwhile all flora, fauna, and fungi are subject to the whims of a “death lottery” with predation, accidents, herbivory, disease and plain bad luck ending their time on Earth. Additionally, every animal species must, of necessity, defecate, getting rid of food wastes. What, then, becomes of the deceased? And why don’t we see corpses or piles of scat piling up across our Sky Island landscapes?
Nature wastes little and will recycle what is left over. Scavengers consume dead animal and/or plant material, assisting decomposers by breaking down the organic matter and dead material into small pieces which are then digested by the decomposers. Decomposers—including fungi, bacteria, invertebrates such as worms and insects—break down the remains into smaller particles and create new, usable compounds and nutrients, like nitrogen, phosphorus and carbon. Without this cadre of diverse species, nutrient cycling would come to a screeching halt.
Perhaps the slickest and most efficient of our Sky Islands scavengers is the common raven. This species is renowned for finding dead bodies— whether they died from predation, accident, disease or some other device being a moot point. Ravens have even, infamously, helped themselves to more than a few Homo sapiens during times of war and pestilence. Able to fly long distances each day, they find their macabre fare mainly via their superb vision, though controlled experiments indicate that a decent sense of smell might also factor into the equation. Hardly alone in their quest for flesh, common ravens are joined by their smaller cousins, Chihuahuan ravens, as well as turkey vultures, black vultures and even crested caracaras and golden eagles in the avian undertaker category.
By removing carcasses from the environment before putrefaction, scavengers prevent the build‐up of toxins in the environment and remove potential disease reservoirs. Without them, one shudders to think of the potential for various pathogens in the environment.
Decomposers help nutrients cycle through various ecosystems, essentially composting the dead. One of my personal favorites are dung beetles. This group of attractive scarab beetles are easy to observe during the monsoon. Simply find a suitable pile of excrement, deposit yourself nearby and wait. Sooner or later the tantalizing aroma draws in the beetles. Most dung beetles arrive by air, as they are accomplished, albeit noisy, aerialists. Landing near a pile of dung, they then ambulate towards their goal. If you are fortunate, you will observe more than one species at your scat. All dung beetles are stout-bodied with a wide thorax and small head sporting short antennae. Many species are charcoal black while others are a dazzling iridescent, metallic green—real stunners.
Regardless of the species, the different types of dung beetles compete for the nutrients in the scat—be it a pile of collared peccary poop, a rope of coyote excrement or some other toothsome treat. Some roll balls of dung within which to deposit eggs, others do not, yet all rely on this unlikely source of sustenance. Without our diverse lineup of dung beetles, we surely would be stepping in it more often.
We conclude our survey with the bane of many southwestern homeowners: desert encrusting termites. This species that has driven humans to distraction proves to be a vital decomposer in the wild. With gut flora capable of digesting cellulose, termites accomplish the difficult task of transforming dead plants’ parts into nutrients that once again become available for more plant growth. And their underground tunnels permit a much higher level of moisture infiltration into the soil—another spur to plant growth. Take these incalculably numerous social insects out of various local environments—mostly deserts, grasslands and woodlands—and watch the dead plants pile up. An excess of dead plant material would equate to a higher risk of wildfires, as well as greatly reducing nutrient cycling.
Space in this column is not ample enough to truly sing the praises of our Sky Islands undertakers and recyclers, from fungi, who transform the dead once again into the living, to the larvae of spectacular Hercules beetles consuming rotting wood, to coyotes scavenging their way across the landscape.
Humans have often reviled these seeming harbingers of death—think where toadstools, vultures, termites, slugs, and other such decomposers rank in our hierarchy of favorite species. Yet without them the landscape would truly be dead.
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS, 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 ravensnatureschool.org