As we pulled into the driveway of La Selva Biological Station, the heavens opened as if on cue. The rain didn’t bother to build with a crescendo. It started abruptly and remained full on fortissimo. We retreated to the shelter of the dining area and set up base on the veranda. We didn’t want to get soaked through just yet and besides, there would be plenty of opportunity for that.
La Selva Biological Station is a large protected area situated in the Caribbean lowlands of Costa Rica. Owned by the Organisation for Tropical Studies, La Selva is renowned for the large quantities of research that is conducted on site each year. We had arrived in mid-January, supposedly at the beginning of the dry season. However, according to the guides, the weather had been unseasonably wet and cool over the last couple of days and the worst was yet to come. We weren’t complaining though. It felt authentic. We were in the rainforest after all!
We sat back on the veranda, Café and binoculars in hand. There were plenty of fruiting trees planted in the courtyard and oh boy were they a magnet for wildlife! One of the most regular visitors was a group of Passerini’s Tanagers. Male Passerini’s have smart and sleek black plumage but when they’re feeling saucy they flash their exquisite ruby red rumps to the ladies. They sure do set the heart racing. Crested Guans and their even more regal looking cousins Great Curassows marched around, feeding on the fallen fruits. In front of the veranda there was lots of flowering Heliconias which proved irresistible to the White-collared Manakins, the males of which are plump and dapper and equally irresistible to watch! About every ten minutes a Long-billed Hermit hummingbird would briskly appear and frantically feed from a Heliconica right next to where we were sitting. Within seconds it would zip away, vanishing into the dense forest. We were witnessing a behaviour known as trap-lining. Trap-line feeders such as hermits follow established routes through the forest to visit seasonal flowers and have been known to loop around these circuits to the second! A troop of 6 soggy Howler Monkeys appeared. They were sopping wet and although they surely must be used to the rain, it was difficult not to anthropomorphise and feel a little sorry for them. Howlers have rather expressive faces and some of them looked pretty hopeless, faces drooping and dripping.
Suddenly the rain eased off as if the thunderclouds had exhausted themselves. We seized the opportunity to head to our cabin, situated about 1km away and reached via a forest trail. We dumped our bags in the cabin and quickly headed back out, unaware of the incredible bird we were about to behold. We were watching a pair of green ibis on a muddy track when quite unexpectedly, Ben spluttered out a series of uncharacteristic expletives. Next to the ibis was a truly strange and amazing bird – a Sunbittern! We edged closer down the track so that we could make out the birds beautiful mottled grey and ochre plumage, which makes the bird so cryptic and notoriously difficult to spot. The Sunbittern flew into a low-hanging branch and we crouched a few metres away. The bird has a really strange character, a squat body and thin, snake-like neck. It even sounds reptilian – uttering a raspy, hiss like call. Perhaps this is aposematic and a technique to deter predators? It’s fair to say that all three of us were chuffed about seeing the Sunbittern and the envy of many of our course mates and lecturers!
Every night we donned our raincoats, wellies and head-torches and ventured into the forest spotlighting. Over the course of three nights we encountered a whole range of awesome nocturnal creatures. This included the ‘classic’ rainforest frog: the Red-eyed Tree Frog. With their striking green bodies, blue and yellow striped flanks, orange legs and bold red eyes they are just as funky in real life as all the cartoon drawings make them out to be! We also had our first close encounters with snakes. My favourite was what I believe to be Imantodes cenchoa, known commonly as the fiddle-string snake! This snake was as slender as a bootlace but with a blunt and chunky head. Pale yellow-brown in colour with bold black spots down its length, the snake was really conspicuous as it lay curled up on a wet leaf. Possibly my personal highlight from the night walks was coming across a pair of Io moths (Automeris postalbida), which had been attracted to a light. At first glance these large moths are just a drab and boring brown and nothing much to look at. But open their wings and, oh my, they’re quite a sight to behold! Each cream-coloured hindwing is adorned with two large black central eyespots and bordered by a flash of bright orange. These big eyespots most likely play a role in predator deterrence and some scientists suggest that predators mistake them for the eyes of hawks.
It was not just during the night that we searched high and low for amphibains. There were two species, in particular, we were very keen to see. These were both poison-dart frogs and although we heard them ‘peep-peeping’ regularly, their small size and habit of hiding amongst leaf litter made them very difficult to locate! The first species was the Green and Black Poison-dart Frog (Dendrobates auratus). This name might make you conjure up images of a dark chocolate frog, but I doubt anyone would want to eat this highly toxic species! The second species was the Strawberry Poison-dart Frog (Oophaga pumilio). Again, sounds tasty, but this tiny beast, not much bigger than my thumbnail, contains enough poison to make you very ill! Both these species loose their toxicity in captivity. This probably means that they accumulate their toxins from certain ants and other critters that they feed on.
Each morning we awoke to the deep and guttural chorus of Howler Monkeys resonating through the forest. This sound is powerful and spine-tingling and overpowered any quieter calls of forest birds. Great Green Macaws win the award for the most pre-historic sounding call. The males utter a creaking and rasping ‘raaaak’, which carries a great distance. Yet it is the Montezuma Oropendola call that really delights me. Displaying males produce a luscious call that bubbles up and then rapidly falls like a cascading waterfall. It gives me goosebumps.
Perhaps the best place for birdwatching was from the large iron bridge that spanned the Río Puerto Viejo. From here we were treated to unobstructed views of the trees overhanging the river and on one occasion we witnessed a mega feeding flock passing through. This included a whole array of species busily feeding, including a Squirrel Cuckoo, Rufous-tailed Jacamar and Masked Tityra as well as woodpeckers, warblers and woodcreepers. One can walk for hours in the forest without seeing a single bird, so to witness this feeding bonanza was a real treat!
I started this piece by talking about the rain and although I’ve tried my best to avoid it for the majority of the blog, I feel obliged to finish with it too. The rain really did define our stay at La Selva. I truly have never experienced so much heavy and persistent rain in my life, and never felt so sodden. Raincoats and ponchos were little match against the furious rain and wearing wellies was like wearing buckets on your feet. On our second day, La Selva experienced an astonishing 103mm in 24 hours. To put that into perspective Cornwall receives about 120mm of rain in December and that is the wettest month! On our last day, the flood arrived. Rain that had fallen at higher elevations made its way into the mighty river which swelled greatly overnight. The next morning the path we usually walked to the cafeteria was closed and the road was underwater. I never thought I would have to get on a boat just to have my breakfast!
There’s nothing quite like being immersed in the forest, with the canopy towering high above and the rain cascading down off the leaves. The forest is an incredible place to be. Coming from a country that is so devoid of trees and missing much of its biodiversity, it’s strange to feel so insignificant compared to the natural surroundings.