Crocs: The Dinosaurs of San Pedro

The Island Newspaper, Ambergris Caye, Belize            Vol. 17, No. 20            May 17, 2007

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Roaming the earth 84 million years ago, Crocodilians are truly living dinosaurs. Their name stems from the Greek word krokodeilos meaning “pebble-worm”, referring to the appearance of their skin. Worldwide there are 23 species of Crocodilians, all of which are in danger of extinction. The wetland habitats of Belize are one of the last refuges for two species of the genus Crocodylus: the freshwater Morelet’s Crocodile, Crocodylus moreletii, and the saltwater tolerant, San Pedro resident, American Crocodile, Crocodylus acutus. Both species are regarded as threatened by the Belize Department of Fisheries and are protected under the Belize Wildlife Protection Act (Chapter 220).

    American Crocodiles are physically distinguishable from the Morelet’s by the presence of a pre-orbital hump which is a bump on the top of their snout in front of their eyes. They are also capable of growing much larger than their freshwater relatives and can reach lengths of up to 22 feet. They are able to tolerate the high salinity of the sea by excreting salt through a modified salivary gland on the tongue and through the feces.

    Crocodile skin consists of non-overlapping scales covering interlocking bony plates called osteoderms, or scutes, providing them with a tough armor. Acting as solar panels, upright scutes along their back increase surface area to absorb heat more efficiently. Relying on external means to regulate their body temperature, ectothermic crocodiles are often seen resting with their mouth wide open. This behavior is called gaping and cools the crocodile down much like a dog panting.

    Like birds, crocodiles have a four-chambered heart and air spaces in their bones which reduce their weight without compromising bone strength. Their teeth are hollow with a next tooth already growing inside. When they lose a tooth there is an immediate replacement through out their life. Crocodile stomachs have the strongest acid of any known animal and can digest bones, antler as well as horn. They are capable of slowing their rate of digestion during cold weather, allowing them to go months without food. As juveniles their diet consists of insects, snails, frogs, crabs and small fish while adults feed primarily on small mammals, birds, turtles, crabs and larger fish, preferring mullet as a major food source. Crocodiles are avid “fishermen” regurgitating food as bait to attract fish closer to their mouth to feed upon. Having a two chambered stomach, crocs will swallow stones to help grind food in the first chamber while nutrient absorption takes place in the second. The stones also play a role as a ballast to help the animals remain submerged for long periods of time. Although crocodiles are able to hold their breath for up to two hours if they remain inactive, they usually only submerge for short durations or up to 30 minutes if threatened.

    Reaching sexual maturity at six to eight feet, or seven to ten years of age, crocodiles have complex courtship behaviors which can last up to two months. In Belize, breeding season typically begins in January after which 20-60 eggs are laid in a hole or mound nest. Covered with sand, the eggs will incubate for about 90 days in the heat of the sun while the female and often the males as well vigorously guard the nest. With the onset of rainy season the hatchlings will call out. The female will then dig them up and carry them one by one in her mighty jaws to a nursery site along the waters edge. Even though the hatchlings are capable of fending for themselves from birth, females have been observed protecting them for over a year. It’s estimated that only one hatchling per nest will survive to reach sexual maturity with most succumbing to predators including large shore birds such as egrets and herons; large fish like barracuda; mammals and even other crocodiles. Add to this nest site destruction due to development combined with the effects of water pollution on hatchling immune systems and one can clearly see that they are a critical species in terms of need for conservation.

    Extremely vocal, Crocodilians brains are more developed then any other reptile. Their sensory organs are exceptionally well developed and crocodiles can actually see in color. Largely nocturnal, their eye site is best in low light conditions and the eyelids, nictating membranes, although transparent do not allow the animal to focus underwater. In addition, their acute hearing and smelling capabilities out of water are muffled underwater as both the ear drums and the nostrils have moveable flaps to shunt water while submerged. This by no means hinders the animal as crocodile’s snouts are covered with visible sensory pits, seen as black spots and called dermal pressure receptors, which detect water pressure changes and vibrations enabling them to detect prey and danger even in the total darkness of murky waters.

    At the top of their food chain, the only known enemy of Crocodilians in Belize is man. Through fear and misunderstanding these animals are killed needlessly yet today. As a tourist attraction the feeding of these animals indirectly leads to their death by unbalancing their natural feeding and thus leading to malnutrition, disease and skin disorders and by drawing the animals closer to human populations creating the possible need to remove problematic crocodiles by destroying them. Relocation is not an option with problem crocs for they will swim hundreds of miles and even cross land over long distances to return to their original habitat. Currently seeking funding, the American Crocodile Endangered Sanctuary is devoted to providing a secure natural environment for problematic crocodiles to ensure their survival and enable research and educational opportunities for both residents and visitors of Belize alike.

    Sadly, American Crocodile populations in Belize are decreasing due to the destruction of major nesting grounds, low hatchling survival rates, needless killings and insufficient means to adequately enforce protection laws. Nesting areas on Belize’s cayes and mangrove habitats are currently threatened by development. According to the most recent research report prepared for the World Wildlife Fund Mesoamerica (Nichols, 2005), extensive land clearing and burning destroyed numerous incubating nests on Northern Caye, Turneffe Atoll, Belize’s prime American Crocodile nesting area. In sight of this increase in competing forms of land use, the preservation of crocodiles will ultimately depend on maintaining suitable wetland habitat.

    Attributable to such development, not only are crocodile wetland habitats in danger of devastation but crocodile and human encounters are imminent. By augmenting public awareness through education, human-crocodile interactions can become safer for both species. It is critically important that we all take measures immediately to help protect this exploited species. The preservation of Belize’s ecosystems as well as obeying wildlife viewing laws and protected species regulations is crucial in assuring the recovery of American Crocodiles and essential for this critically vulnerable species to once again become self-sustained. American Crocodiles were residents of Belize’s cayes long before any humans and we must try to understand their actions in relation to our own while never underestimating their intelligence.

    Submitted by Biologist Cherie Chenot-Rose, Executive Director, ACES/American Crocodile Endangered Sanctuary, Toledo, Belize, Central America. Photos Courtesy of Cherie and Vince Rose.
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