Tropical Dry forest, seems self explanatory, simple to conceptualize. Typical of low elevations in the tropics these areas are warm. With little rainfall or not too much water, they are dry. While a good starting point things do get a little more complicated, and variable. The dry forest environs of the pacific coast of middle and much of Central America do receive a substantial amount of rain. Guanacaste Province in Costa Rica averages between 1500 and 1600mm annually (59 and 63 inches). This is enough moisture to support a forest, one with tall trees and a closed canopy. It is however a situation of extremes, one in which most of that amount of rainfall happens in just half a year, and the other 6 months is dry. It is the age old game of adaptation, of survival, of organism utilizing the available resources to prosper and continue through thousands of years of Mother Nature's gifts and punishments.

So when it begins to rains, at the start of the wet season, when thunderstorms rage, the broad leaved trees unfurl new lush green leaves, as trees would in the temperate regions spring season. These leaves capture the strong tropical sunshine, they transpire—pull plentiful moisture from the soil, they photosynthesize, flower and fruit. These plants do this for months of hot and humid tropical weather, with daily convective thunderstorms. With the foliage, the rest of the forest pulses with vigor, insects, flowers and then fruits proliferate, and the creatures that depend on these meet them with open mouths, and beaks.

With changing wind patterns and changing weather, the rainfall subsides, leaving the hot tropical sun, a baking sun, to parch the foliage. To survive in this game the plants have adapted. The broad leaved plants, lose their leaves, they fall as if in the temperate autumn. More light now finds the strata below, the understory, shrub and herbaceous layer. Within any forest there are subtle and not so subtle differences in terrain and moisture availability, differences in soils and slopes. There is still greenery, or “olive-tan-ery”. Along river drainages, creeks, and waterholes there will still be tall trees, which may retain their leaves. Where there is water in the now dry, there are the creatures that need and seek it. The dryer it gets, the more frequented such wet spots become. Go to a good waterhole, in the driest part of the dry season and sit quietly. Watch the bees and wasps visit the muddy edges, listen for the flutter of wings, as doves alight, and listen for the quiet footsteps of the Great Curassow, and White-tailed Deer, and if you are lucky you'll eventually be visited by a troop of White-faced Capuchin Monkeys, or a troop of inquisitive Coatimundis..

To do this right bring a comfortable lounge chair, a cooler, and maybe an assistant to tap your shoulder when something good arrives, should you nod off to the hum of bees, plaintive cooing of doves, and songs of wrens.

The White-tipped Dove (Leptotila verreauxi) on approach to a waterhole in Santa Rosa National Park in Costa Rica. It is also the mellow cooing sound in the embedded mp3 file which loads with the page. A very common bird, and an even more common sound. This stereo recording also includes barks from Elegant Trogon (Trogon elegans) "tea-mu" whistles from the Long-tailed Manakin (Chiroxiphia linearis), a bouncing rattle from Barred Antshrike (Thamnophilus doliatus), and some comical chortals from Rufous-naped Wrens (Campylorhynchus rufinucha) at the end.

Tropical Dry Forest
(Guanacaste Province, Costa Rica)
by David L. Ross, Jr.