Coming from the rainy, chilly highlands of Cuericí, the climate of Palo Verde is a stark contrast. Down here at sea level we’ve got daily high temperatures in the 80s and 90s F, and that’s with tropical sun (i.e. sunlight coming in at a near-perpendicular angle to the Earth). At this time of year, Palo Verde is sporting a dry heat—the kind that makes your hair start to dry while you’re still in the shower, and turns popsicles into puddles in a matter of seconds.
First to welcome us to the dry forest are a group of white-faced capuchins, which we quickly learn are a common sight around the station and up in the forest’s canopy. Not only do we have the company of the capuchins, but in the early morning, the loud, echoing calls of male howler monkeys are heard no matter where you are. These throaty, growl-like calls that awaken the forest sound somewhere in-between a lion’s roar and a very hungry stomach.
Temperature and some new mammal species aren’t the only big changes from previous locations. Palo Verde is our first site with a wetland habitat, adjacent to its tropical dry forest. Located downstream of the Río Tempisque is a brackish marsh, which is substantially desiccated during this dry season. Despite its being reduced to a collection of large puddles, the marsh provides a home to waterfowl such as the roseate spoonbill, black-bellied whistling duck, Northern jacana, and black-necked stilt. An observation tower that overlooks the marsh is just a few minutes’ walk from the station’s main campus and an excellent place to observe these species up-close—I like to go just after sunrise or in the late afternoon, when the pleasantly warm temperature is accompanied by a salty breeze.
The first thing you notice is that the individual birds like to clump by species. The small jacanas have claimed the shallowest part of the marsh, closest to shore. Using their long, narrow bills, they pick at bits of floating vegetation or at the water surface and occasionally come up with a wormy-looking creature. Further out in the marsh you’ll find the black-necked stilts, taller than the jacanas and with even narrower, needle-like bills. Instead of just scraping the surface like the jacanas, a stilt shoves its whole bill and part of its head down into the water, rustles around for a second, and then comes up with a dripping face but no apparent prey (as it turns out, the stilts feed on aquatic invertebrates or fish, so it likely swallowed its meal while underwater.).
The whistling ducks are grouped together on the small islands of vegetation interspersed here and there, or slowly paddling through the marsh. Every now and then the they’ll do the typical duck half-flip underwater, shimmy their tail feathers, and resurface. Look a meter or two farther out and you’ll find the roseate spoonbills, tall and flamingo-pink. Their feeding method is the most intriguing to watch—with their aptly-named bill slightly opened, they sweep it side to side just under the water’s surface. Every now and then they find something tasty, stop mid-sweep, nibble at their prey in a flurry of splashes, and then continue on with their sweeping.
The marsh is so calm and peaceful that you would never guess what is lurking a few kilometers down the road at the source of this wetland’s water, the Río Tempisque. Sun-bathing along the banks of the river or floating downstream as driftwood look-alikes are none other than crocodiles! From the river’s dock you can get a nice look at these incredible reptiles—just be sure not to sit on the edge with your legs dangling…