Saturday, June 11, 2016

Costa Rica Part 9: Crocs and critters along Rio Tarcoles

Say ahhhhhhhh...  A young American Crocodile lounges on a muddy riverbank along Rio Tarcoles. During this stop on our Caravan Tour we took a boat trip through the estuary formed where the river meets the Pacific Ocean in Costa Rica's Puntarenas Province. The country immediately around the river is flat, with swamps and lagoons where crocodiles abound. For a Google map showing the mouth of Rio Tarcoles, click here.

Launching the cruise

Our boat captain expertly maneuvered his craft around the river's islands and inlets. The boat is part of a small fleet owned by Jungle Crocodile Safaris. In addition to the boat captain, the tour included a bilingual guide to help us spot the animals. The company was founded in 1993 by Mario Fernando Orjuela Castro, a veterinarian who specialized in species such as crocodiles, boas, and iguanas. Tours last about two hours.

The boat captain's choice of a t-shirt provoked nervous chuckles among his passengers. While the boats are safe and this species of croc is not supposed to be aggressive toward people, I wasn't eager to test the theory. The Rio Tarcoles runs along the edge of Parque Nacional Carara before emptying into the ocean. The park is large, with an area of 5,242 hectares (12,953 acres), and it contains multiple ecosystems.

The tour boat was roomy and afforded good views from every seat. The craft was long, narrow, and had a flat bottom. This enabled the captain to move up narrow channels and drift along close to shore. While most folks wore their life jackets, you can see that a couple of youthful types decided against it. I guess they figured "why worry about drowning if you are going to get eaten anyway?" Or maybe they just counted on the invulnerability of the young.

Another tour boat approaches from up-river. This view gives an idea of the terrain. Near the shore, the country is relatively flat and covered with palms and other vegetation. A bit further back are heavily wooded foothills while, in the far distance, the Coast Range looms.

The river crocs

A tour boat employee warily eyes a croc floating a few feet from the boat stairs. The ridge of the croc's back can be seen just below the vegetation to the left of the photo's center. The creature could easily be mistaken for a floating log, which is one of the croc's prime hunting strategies. This species of American Crocodile (Crocodylus acutus) is not traditionally aggressive toward humans. However, some tour guides have been known to entertain tourists by feeding the crocs. This has led the creatures to associate humans with food, not a good idea. After a series of attacks on people, environmental officials began to enforce an existing law against such feeding.

A young croc floats lazily in the brown water. This one was probably about 2m (6 ft) long. Although not big for a croc on this river, he might still be capable of pulling you under or at least giving you a very nasty bite. It's well to remember that you are not in a petting zoo. Only one fatality has occurred on Rio Tarcoles since 1995, but there have been numerous non-fatal attacks. Some of these have resulted in the loss of limbs. The one fatality occurred when a drunken man decided to take a swim near a bridge from which tourists regularly throw meat to the crocs. The inebriated swimmer was literally ripped to shreds by a pack of crocs as the tourists above watched in horror.

Osama, King of the River. Near the middle of the river, we encountered this guy, affectionately dubbed Osama by the boatmen. At about 6m (18 ft), he is the largest croc in the area. This is close to the maximum size that this species reaches. He is estimated to weigh 907kg (2000 lbs). Osama floated serenely past us, before turning to continue on another leg of his patrol. Crocodiles have inhabited the planet for over 200 million years and are considered living dinosaurs. American Crocodiles can be found from southern Florida to Brazil and all along the Pacific Coast from Mexico to Central and South America. Their territory is primarily coastal, but they can also be found in rivers with a degree of salinity, such as Rio Tarcoles.

Another view of the young croc on the shore. Keeping his mouths open like this is a strategy for cooling his body. Fish, reptiles, birds, and small mammals are the usual diet, along with the occasional deer. One way to distinguish a crocodile from an alligator is the snout. A croc's is narrower and more V-shaped than the blunt, rounded snout of an alligator. Alligators can tolerate colder temperatures than crocodiles and so their territories don't usually overlap.

A baby croc slithers along a mudflat. This one was about 0.3m (1 ft), not much bigger than a hatchling. He was well camouflaged and difficult to spot at first. The mother croc will fiercely defend her eggs and newly hatched young. When danger threatens, she will gather the hatchlings in her mouth and carry them to the safety of nearby water.

Birds along the banks

An Osprey inspects the river below, possibly looking for a tasty bit of fish for lunch. As we cruised the channels and riverbanks, we saw a wide variety of birds. The Osprey (Pandion haliaetvus) is Costa Rica's largest raptor. It's talons are especially adapted to fishing, with two toes facing forward and two back. This enables the bird to grip with the fish's head forward, making for more efficient flight. The Osprey also has valves in its nostrils that close when it hits the water. It is a migratory bird, traveling from Florida to Brazil, with stops in Costa Rica or elsewhere along the way. Most of the birds I show here were identified for me by either Tom Holeman or Georgia Conti, my two bird experts. My thanks to both.

The Black-necked Stilt is a wading bird. Its legs are longer than some other wading birds, allowing the bird to fish in deeper water. This species of Stilt (Himantropus mexicanus) has an extremely sensitive bill that it uses to probe the mud for worms, tadpoles, crustaceans, and small fish. Most Black-necked Stilts are residents of Costa Rica's coastal areas, but some are migratory from the Caribbean. (Bird i.d. by Tom Holeman)

Yellow-crowned night-herons live in marshes and estuaries. They can be found along Costa Rica's Caribbean and Pacific Coasts. The Yellow-crown night-heron (Nyctanassa violacea) gets the last part of its common name because it is a night-hunter. However, the bird will also feed during the day if the tidal conditions are right. Its thick bill is especially adapted to catching crabs and crayfish. (Bird i.d. by Georgia Conti)

The Tri-colored Heron is one of several species of heron found in Costa Rica. It can be distinguished by the white and chestnut stripe down its throat. The Tri-colored Heron (Egretta tricolour) is found along both of Costa Rica's coasts in river estuaries, marshes, and mangrove lagoons. In addition to striding slowly through the water while feeding, it will also use its feet to stir up prey from the bottom. Sometimes the Tricolored Heron will crouch, hop, and then spear its prey with its sharp beak. (Bird i.d. by Tom Holeman)

The Wood stork's head and beak give it a dinosaur-era appearance. In fact, the Wood Stork (Mycteria americana) looks strong enough to carry a baby in a cloth sling from its beak, as seen in the cartoons. It is the second tallest bird in Costa Rica, after the Jabiru. This stork may look similar to an egret, but it is actually more closely related to vultures. When feeding, the bird doesn't spear prey with its beak but wades along with its beak open in the water. When prey is contacted, the beak snaps shut. The Wood Stork feeds on small to medium-side fish, crayfish, frogs, and even recently hatched caimans. (Bird i.d. by Tom Holeman)

Willets are part of the sandpiper family and are very common on Costa Rica's coasts. Willets (Catoptrophorus semipalmatus) are locally called Pigüilo. These birds are quite noisy, making sounds like "keeek" and "whreek." Some Willets migrate from Costa Rica through Panama to the South American coasts, but others remain in residence here. And why not? The Costa Rican humans' favorite saying is Pura Vida ("Pure Life").  If you listen closely, you may hear the resident Willets call out the same thing. (Bird i.d. by Tom Holeman)

A small flock of Neotropic cormorants perches on the dead branches of a tree. Neotropic Cormorants (Phalacrocorax brasilianus) are also called Olivaceous Cormorants. They are about the size of small ducks and have been around for a long time. Fossil evidence for cormorants goes back 30 million years. In order to better chase fish, their primary prey, the cormorants' legs are set far back on their bodies. Like Brown Pelicans, they will sometimes dive to fish. Other times, like White Pelicans, they swim in groups in order to herd the fish close to shore so they can more easily gobble them up. (Bird i.d. by Tom Holeman)

Other interesting river residents

A Double-crested basilisk lizard suns itself on a riverbank boulder. We saw another of these on our Rio Frio cruise, but that one was bright green. The proper name for this creature is Basiliscus plumifrons. The common name comes from the two separate crests along the lizard's body and tail. They can be found along river banks throughout Central and northern South America.

A pair of white-breasted bald-headed marimba players. Very common in this region. They are generally found in pairs or even trios near commercial feeding areas. To attract attention, and thus sustenance, they create a peculiarly pleasant musical sound. Their major method of feeding themselves is through something called "tips".

This completes Part 9 of my Costa Rica series. I hope you enjoyed it and, if so, you will leave any questions or comments in the Comments section below or email me directly. If you do leave a question in the Comments section, PLEASE include your email address so that I can respond.

Hasta luego, Jim

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If your comment involves a question, please leave your email address so I can answer you. Thanks, Jim