From the Crocodile Bay Lodge, Puerto Jiménez
Crocodile Bay Lodge is closed in October so read the Eco Report by Brian Strehlow, their
Naturalist Guide
As it turns out, one of our local residents has a lot more going for it than its winning smile and charming personality. He not only has some of the most unique characteristics and behaviors amongst its peers, but also is far more selective as to where it lives, limiting itself to a tiny portion of Costa Rica. This adorable and amiable neighbor goes by the name Saimiri oestedii, its more common name, the Central American Squirrel Monkey. Unlike the other species of monkey found throughout Central America, the squirrel monkey is confined to a small stretch of Pacific lowlands in southern Costa Rica.
Due to their geographic isolation, the Central American Squirrel Monkey has evolved in unique ways. For example, the males show aggression so infrequently among themselves that researchers can’t discern any dominance hierarchies. According to some researchers, there is no less-aggressive primate society.
These monkeys are also remarkable among other primates because they give birth at the same time each year. Primates, including humans, are distinct among mammals in that females experience estrus throughout the year, as apposed to “going into heat” at specific times. However, these squirrel monkeys perform “birth synchrony,“ concentrating births into a two-month period, with the majority born within just one week. Being particularly vulnerable to predators, such as falcons and hawks, this technique is believed to decrease infant mortality rates.
At least as curious is the males’ technique for attracting a mate. Male squirrel monkeys fatten, increasing their body size by 20 percent, as a part of courtship. Unique to their genus, males are capable of converting their testosterone into estrogen, causing them to retain water and swell in body size.
Not to be left out, the female squirrel monkey is unusual in that it is often her that will emigrate from one troop to another. In most species, the males transfer, as nature’s way of avoiding inbreeding.
As endearing and curious as the squirrel monkey is, it still faces some fierce opponents. Capture for the pet trade and biomedical research has taken its toll. In fact, the squirrel monkey is the second most common primate used in medical research in the U.S., after rhesus macaques.
A far greater problem has been habitat loss. It stands to reason that, as the landscape of Central America has been altered by human endeavors, the species with the smallest numbers and range would feel the most impact. Hence, the squirrel monkey is the most endangered monkey specie in Central America. In a process that began in 1938, with the arrival of the United Fruit Company, massive tracks of the Pacific lowlands have been cleared and replaced with banana and oil palm plantations, as well as countless smaller beef cattle and other farms. In fact, the specie has almost completely vanished from its southern range in northwestern Panama, due to lack of conservation.
You may be wondering, at this point, why an entity designed to promote Costa Rican tourism would delve into such dark and depressing subject matter. Allow me to share with you the good news. The Osa Peninsula, home to Crocodile Bay Lodge, is the bright light in this sea of darkness. Not only is the Central American Squirrel Monkey abundant and easy to find on the Osa, but it is also believed by biologists to harbor the only sustainable population. In other words, the population and habitat are large enough to allow for enough genetic diversity to insure their overall health and survival. Thanks to conservation efforts on the peninsula the Central American Squirrel Monkey is going nowhere fast, except that is, on its own hands and feet.
Pura Vida…Brian Strehlow
Naturalist Guide
Crocodile Bay Lodge
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