Protected under the WildLife Protection Act

AMERICAN CROCODILE

Class: Reptilia

INTRODUCTION 

There are 22 species of living crocodilians belonging to a single family (the Crocodylinae) within the Order Crocodilia. In this order are three subfamilies; Alhgatorinae (contains Alligators and caimans), Crocodilinae ("true" crocodiles) and Gavialinae (gharial and false gharial). The American Crocodile, Crocodylus acutus, found in the subfamily Crocodilinae, is thought to have inhabited Jamaica from the time of the islands formation when it drifted away from other land masses. Crocodiles and their kin have been on the earth for over 200 million years with hardly a change in their body form.

The American Crocodile range from central Mexico south through parts of Central America and northern South America to northern Peru on its Pacific coastline and Venezuela on its Caribbean coastline. In addition, they are present in extreme southern Florida, Cuba, Haiti and the Dominican Republic. Crocodiles are primarily coastal animals in nature inhabiting wetlands, brackish bays, lakes and the lower reaches of large rivers.

While in most areas they were widespread and often in abundance, they are now severely depleted throughout its range within the last century, mainly due to hunting for skins but aggravated by habitat loss. One of the most dense population is in Lago Enriquillo in the Dominican Republic where 175 to 250 adults may remain.

One of Jamaica's largest reptile, the American Crocodile can be seen on the Royal Helmet and Mantles on the Jamaican Coat of Arms and as such it is a part of our natural heritage.

The development of any management strategy for the American crocodile must take into account the following likely influences:-

The extent to which they are hunted.

The duration and effectiveness of protective legislation.

The extent to which the crocodile population have recovered.

Peoples perception of crocodiles.

In the strategy to manage the crocodile population, one aim is to preserve the species and thus re-establish a viable population in the wild or where the species can't recover substantially ECOLOGY.

Ecology

The crocodile is a large lizard-shaped reptile and has a strong muscular tail, four short legs and five toes on each foot. Their backs are covered with bony plates called osteodermis and these form a dorsal armour on their body. Adults are grayish-green on the back and tail, and have a white or yellowish underside, while young crocodiles have dark cross bands on their back and tail. The snout of the crocodile is narrow and triangular, and when closed the fourth tooth is exposed. At the end of the snout are the nostrils. On the top of the head, behind the eyes, are the ear drums. A movable flap of skin protects the ear drums. The position of the eyes, ear drums and nostrils allows the crocodile to be partially submerged exposing only the top its head, and yet still being able to see, hear and breathe. Male crocodiles are larger than females and range in size from 6-12 feet.

 Distribution and Habitat

In Jamaica, crocodile habitats are mainly concentrated in the southern section of the island within mangrove swamps and marshes, shallow sea bays and brackish to saline lagoons. There are large fresh water swamps and peat marsh systems along the Black River and in Negril, but otherwise there are few freshwater wetlands of any major significance.

 Food and Growth

The adult crocodile's jaw has conically pointed teeth which interlock and are therefore more suitable for grabbing, holding and tearing prey, rather than cutting or chewing. They have good teeth replacement as reserve teeth are continually growing and push out the older worn tooth. Food is crushed and torn into large chunks and then swallowed. It takes approximately 72 hours for food eaten to be digested and eliminated as waste.

Crocodiles eat any living or dead animal including humans. The bigger they are the larger the prey. Adults can successfully hunt larger animals, including small- mammals, fish, turtles, birds and crustaceans. The larger animals are crushed by a series of bites along their length. Hatchlings and young crocodiles eat mainly small prey - insects, snails, frogs, crustaceans and small fish.

Crocodiles do not have a regular constant diet. Temperature is one factor that affects their feeding habit. The animal eating habit varies with body temperature. The crocodile consumes less than its normal intake on a hot day. It is also documented that cooler temperatures decrease the rate of digestion in a crocodile. Due to the slow rate of digestion, energy conservation is a must. Additional energy is conserved by raising the body temperature in activities suchas basking. This enables the crocodile to survive even when food is scarce. 

Reproduction

Reproduction among crocodilians is the most advanced in reptiles. Sexual maturity of the animal depends on both their size and age. In the wild the crocodile reaches sexual maturity between the ages of eight and ten years, when they are 6 to 8 feet. Unlike birds and mammals, the sex of the unhatched crocodilian embryo is determined by the temperature at which the eggs are incubated. Crocodiles are fertile animals, usually laying so many eggs that the very heavy losses suffered by the early stages have no adverse effect upon their numbers. Mature females usually lay an average of five dozens eggs once per year.

Crocodilians have a social organization in-which the males defend territories by fighting and roaring. The courtship and nesting ritual is protracted and complex, and is likely to occur in late January and February climaxing within 6 to 8 weeks of the ritual. During this period that the crocodiles remain in their inland mangrove swamps habitat. Females construct a hole or mound for their nest.

The mating season usually commences between April to May and eggs are laid from May to July. Females selects an open sandy area either a stretch between the swamp and the sea. The nest are constructed above the high water mark on well drained soil. The female digs a large nest about 5 feet deep and 4 to 6 feet in diameter. Into this she lays up to five dozen eggs. The number of eggs varies from 30 to 60 eggs per nest with the length of the eggs ranging from 60 to 77 cm. The eggs are covered with sand and incubated by heat from the sun's radiation. A den may also be dug near the nest site by the female. Towards the end of incubation females visits to their nest increase in frequency.

When hatching commences, the females digs open the nest, helping the hatchlings emerge from their eggs. The hatchlings are assisted by the female crocodile into the water and subsequently to nursery sites where they are left. Hatchlings thus disperse rapidly, making their departure from the nesting site and begin to fend for themselves.

 Behaviour

The crocodiles behaviour is subtle, complex and quite unlike that of other reptiles. They are basically reserved creatures who prefer to be left undisturbed in their natural habitat. In the wild, they retreat or hide by submerging at the slightest disturbance, however if threatened the may adopt a threatening posture, swell and even attack.

Like other reptiles, crocodiles are ectotherms, that is, they depend on external heat sources to regulate their body temperature. In the morning to gain heat, or lose it rapidly at midday, the mouth of the crocodile is held open, with the lower jaw on the ground. The upper jaw is held at an oblique angle. In the mouth, the blood vessels are close to the skin surface thus facilitating the transference of heat. Basking (lying quietly) is a strategy to warm their body and which increases the rate of food digestion. This is also a strategy to conserve energy due to slow rates of digestion during cold tempreatures.

Crocodiles are mostly active at nights and relatively inactive for the most part of the day. As the river warms slowly in the morning, crocodiles heat up by basking on land. At night, the river cools slowly, so the crocodiles spend the majority of the time submerged to keep warm.

Bouts of activities are powered by anaerobic metabolism, after which a long recovery period is needed. A crocodile reacts quickly and with power, but tires easily. Thus behaviours tends to be sporadic. Once fatigued, large crocodilians takes many hours or even days to recover.

The ability to remain motionless, yet alert, has obvious advantages to an opportunistic predator that relies on stealthy and being cryptic. Large crocodiles have low metabolic rates which thus reduces food requirements. Ableing them to survive for months without feeding if body temperatures remain low.

A high body temperature facilitates digestion. Social interactions displays, typically occur at dawn, when body temperature is lowest and before basking is initiated. Crocodiles forage between dusk and dawn when ambient daily temperature are low and are often inactive during the middle of the day when ambient temperature are highest.

The second unusual feature of crocodilian behaviour relates to their amphibious mode, that is their ability to, live in both aquatic and terrestrial habitats. The can move as well in water as on land and is neither exclusively nocturnal nor diurnal. Their eyes are adapted for nocturnal vision and bright sunlight (close to a vertical slit for acute vision). Membrane covering eye provides protection for seeing underwater.

A most unusual and interesting feature is that they are social. Display an array of social behaviour. Parental care at hatching and post-hatching care of young are probably universal traits within crocodilians.

Dominant males defend territories from which they exclude other males.

HISTORICAL PERSPECTIVE

LEGISLATION

National

In 1970, the numbers of crocodiles in Jamaica had dwindled to a level considered to be threatening imminent extinction of the species, and by 1971, the species was added to the third schedule of the Wild Life Protection Act. The Third Schedule lists animals that are endangered and need protection for continued survival. Under Section 6 of the Wild Life Protection Act, it is an offense for anyone to kill or have in their possession the whole or any part of a crocodile, living or dead.

International

Since January 7, 1975, the American Crocodile, has been listed under Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and in the Protocol on Specially Protected Areas and Wildlife (SPAW).   Species which are listed under Appendix I of CITES include those threatened with extinction and for which trade must be subject to strict regulations and should only be authorized in exceptional circumstances.

THREATS

As Jamaica's human population rises and the encroachment into crocodile habitats increases, there will be further reduction in the quantity and quality of crocodile habitats around the island. The social problem with humans and crocodiles cohabiting has been observed and recorded as far back as 1985, deduced from the development of coastal areas for the purposes of establishment of fish farms, micro-dams and the filling of swamps for urban and industrial development.

The destruction of their habitats has resulted in the decrease in the number of nesting areas and food source. As a result, there has been an increase in the number of reports, received by the NRCA, Hope Zoo, Police and television station regarding crocodile sightings and capture in areas outside their natural habitat. In addition, as urban development expands and encroachment on crocodile habitats increase, sites where they historically traversed to get to nesting areas are now either residential areas or fish ponds. Persons in these areas are now encountering crocodiles on their properties, mainly in fish ponds and in streets and canals.

MANAGEMENT STRATEGIES

The crocodile management plan will consider the different strategies which maybe applicable and whose objectives maybe inter-related. Priority must be given to the ecological survey which will determine when and which of the strategies can be applied.

It must be understood that the information may be costly and time consuming to obtain and although resource experts in the field will be contacted for considerable advice, the management approached may entail some guess work, trial and error, considerations to pressures from conflicting groups, inadequate funds and the consequences of interfering in natures processes.

Needless, other countries have had success stories. It is therefore not necessary to re-invent the wheel. The conservation strategy in total draws from a number of sources. If there is enough thought, clear objectives and policies, with justification, directed in action plans which will arise out of the Management Plan , then Jamaica will be on the right track.

A. Undertaking an Ecological Survey

As one of the objectives is to manage areas for the protection of the crocodile, there is a need measure the species ecological requirements and year round needs. Little is known about Crocodylus acutus true place in the ecosystem of Jamaica's wetlands. Efforts to record the status of the species and existing habitats will permit the development an effective recovery plan.

An understanding of the ecosystem is necessary to institute manipulative management, as is necessary in Jamaica, where there is an absence of vigorous protection of the crocodile habitats, and also little is know about the status of the crocodile population. The causes for the decline must be ascertained and in particular identify the factors limiting the population in each recorded habitat.

The scientific determination includes monitoring the size, range, and age structure of the population, the general habitat characteristics, the factors regulating nesting success, and the limiting population growth.

To date, there has been only reasonable deductions about the status of C. acutus in Jamaica, based logically on the increasing habitat destruction which appears to be the major factor limiting population growth.

The survey will seek to:

Determine the population dynamics by determining the age-size class structure, analysis of survivorship and fertility and emigration.

Determine the actual distribution of C. acutus of Jamaica, and to characterize the quality of habitats in order to determine their presence and relative abundance.

Determine the crocodile's feeding and foraging strategies.

Monitor activity and long distance movements.

Examine the social organization of the various populations.

B. Habitat Protection/Manipulation; Declaration of Sanctuaries/Reserves

To conserve a species population, it is important to maintain the species habitat requirements. The approach to crocodile conservation should therefore be based on the identification and safeguarding of the existing key sites and resources, encouraging positive management, and maintaining and enhancing the wildlife value. This provides a tool for conserving the species in their own habitats so that survival will not depend on a few captive specimens living under captive conditions.

Since the major threat to the crocodiles in Jamaica is the destruction of the habitat, establishing a system of reserves would be most effective in preventing the loss of the species. Ideally, each reserve should be large enough to sustain a viable population.