This year’s local monsoon moisture has been fickle in its arrival – the sixth-driest start ever in our locale. The wetter the winter, the more drought prone is the summer, it seems. As I pen these words in mid-July, only a few fortunate areas have received substantial summer rains.
Once the rains arrive in force, then the sexual clock will be ticking for the legions of plant, animal, and fungal species that mainly or exclusively mate/reproduce after the onset of monsoon season. For these monsoon maters, lust without the dust is certainly a must!
Mating during our wet summer makes biological sense. Monsoon season is warm-to-hot, thus allowing more species to reproduce. Cold and its attendant lack of food is more a deterrent to reproduction than heat for most local species. Further, monsoonal precipitation, however ambivalent this year, is historically more consistent than winter moisture. Rely on winter moisture and you may well have to wait years, if not a decade or more, to reproduce. Witness our spring wildflowers that vary from awe-inspiring to nonexistent based on elusive winter rain and snow. Summer blooms, though less famous, are certainly more consistent in their appearance each year.
Finally, there is the cascade of emergence that allows many species to reproduce during the monsoon. After the ground gets soaked, many warm-season plants and fungi start to germinate, providing food for herbivores. More herbivorous rodents, rabbits, insects, and the like equate to more predators. The food chain flourishes and passions are ignited. The biological imperative to mate – among those species that reproduce sexually – comes into full play.
Take ants for example. Reproductive king and queen ants are essentially “stored” underground or perhaps in a tree hollow until the proper moisture arrives. Following a significant storm, they form mating swarms. There, king meets queen and insemination ensues. She – now perhaps impregnated by multiple males – drops to the ground, sheds her wings, and digs into the conveniently soft earth to found a new colony.
In my personal scale of monsoon precipitation, I have several labels with which to judge the amount of rain received in any one storm. It goes something like this: jokers = very little rain (i.e. a bad joke), soakers = gentle rains that palpably moisten the soil, but cause little runoff, woke-hers = wakes up the wife from a sound sleep and causes some runoff, and finally croakers = prolonged rains that lead to runoff and ephemeral streams and ponds.
Following croakers, toads and frogs of many species rely upon temporary pools for mating. So attuned to the monsoon, for instance, are various spadefoot toad species that they literally may emerge above ground from their subterranean nooks when they hear the thunder violently clap! This distinct sound added to increased soil moisture lures them to the surface. Males find pools within which to call the females towards them. Amplexis, or a mating embrace, follows and the females are soon laying eggs. Given the brief life of their mating pools, the tadpoles then develop with equal speed, emerging in as little as 10 days.
Summer’s warmth provides favorable conditions for the reproduction of many local reptiles. Given that most are oviparous or egg-laying, soil temperatures must exceed a critical limit in order to provide suitable incubation chambers. Skinks, alligator lizards, whiptails, spiny, and other lizards generally find monsoon season optimal for reproduction. So too with most of our snakes and for the same reasons – available prey and suitable egg chambers.
Not only are soil moisture and temperatures conducive to reproduction, but, significantly, the young of these reptiles will enter a world rife with insect and other invertebrate prey. Profound storms deliver life-giving moisture, teasing forth armies of grasshoppers, flights of butterflies, swarms of bees, a myriad of beetles, and more. Now these too will spawn even more reproduction.
While many birds have already mated prior to monsoon season, some reproduce mainly during this wetter, season. Botteri’s sparrows begin singing while clouds amass, and thunder begins to roar. Soon they will be stuffing the beaks of their young with the surfeit of invertebrates. Even granivorous, or seed-eating, birds often adapt their summer diet to a protein rich, invertebrate-laden one to the benefit of their young. Evolution in conjunction with climate has led these birds to become mainly monsoon maters.
Perhaps you too will be inspired by the clouds, coolness, lightning, rushing water, and verdancy!
Vincent Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS, their Nature Adventure & Conservation organization devoted to protecting the unique biodiversity of the Sky Islands region. Visit: www.ravensnatureschool.org