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| Alligators |
| Common Name |
American Alligator |
| Scientific Name |
Alligator
mississippiensis |
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Description |
 Alligator
mississippiensis is one of the best-known crocodilians. It is widespread
in a variety of wetland habitats in the southeastern United States of
America, and under enlightened management programs, has made a
remarkable comeback from the days of uncontrolled hunting. Carefully
controlled harvest programs are now in place in Louisiana, Texas, South
Carolina and Florida.
Alligators are usually associated with fresh or brackish water, with
some individuals venturing into saline water for short periods. Their
principal habitats are swamps and marshes, but they also occur in lakes,
rivers and streams. In Louisiana, adult and subadult males prefer open
water areas and females prefer more secluded, heavily vegetated sites.
 Female alligators lay an average of 40 eggs in a mound nest. Ambient air
temperatures affect the timing of nesting and egg-laying. In Louisiana,
low spring (March-May) temperatures cause nesting to occur as late as
the first week of July, whereas with high ambient temperatures nesting
occurs in early June.
Females mature at about 1.8 m length, and the largest females are about
2.8 m long, Some males may exceed 4 m total length – they rarely exceed
4.5 m, although some historical accounts suggest that some individuals
may get larger.
During cooler months of the year, alligators remain inactive, within
dens. In some cases hatchlings will overwinter with the female in her
den.
Overall, alligator numbers are increasing. In the State of Florida, over
17,000 complaints about "nuisance" alligators are received each year.
Alligators regularly eat dogs and cats, but are generally too small to
be a common predator on humans. Nevertheless, there have been numerous
unprovoked attacks by alligators on people, resulting in 17 fatalities
since the late 1940s.
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| Common Name |
Chinese Alligator |
| Scientific Name |
Alligator sinensis |
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Description |
 The
Chinese Alligator is the only alligatorid outside the Americas, and it
is restricted to the lower Yangtze valley in Anhui, Zhejiang and Jiangsu
Provinces in China. Like the gharials in India, it has fared pretty
badly due to human population pressures. Alligators are mentioned in
Chinese literature from around 1300 BC, and it is possible that the
dragons in Chinese art and mythology were based on this species.
Alligator sinensis is a small species, typically less than 2 m long,
which spends most of its life in burrows. From late October to
mid-April, they hibernate in burrows that they excavated in the sides of
river banks. During the early and late stages of this period they may
leave their burrows, although they are sluggish, but otherwise they do
not feed or move during the period of aestivation. Body functions slow
as temperatures drop - as low as 10C.
Sexual maturity is reached at about 4-5 years of age. Mating occurs in
June, and in July-August 10-40 eggs are laid in a mound nest. Incubation
takes about 70 days, and the hatchlings are typically black with yellow
stripes, about 21 cm long and about 30 g in weight. Diet consists mainly
of snails, mussels and fish, though adults may take larger vertebrate
prey.
Conservation efforts in China allowed a captive breeding Centre in Anhui
Province to be established, and there are now over 10,000 captive
Chinese Alligators. The wild population is now estimated to be less than
150 individuals, with subpopulations small (no more 10 individuals) and
fragmented. Chinese authorities have begun experimental restocking of
wild habitats with captive-bred alligators, with the first releases
being monitored by radio-telemetry to monitor survival and movement.
Efforts are also being made to identify and secure new suitable sites
for future restocking to augment the wild alligator population. The
species is listed as “Critically Endangered” on the IUCN Red List of
Threatened Species.
The species has also bred in captivity in the USA, at Rockefeller Refuge
(Louisiana), Bronx Zoo (New York) and St. Augustine Alligator Farm
Zoological Park (Florida).
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| Caimans |
| Common Name |
Black Caiman |
| Scientific Name |
Melanosuchus
niger |
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Description |
 The
Black Caiman is perhaps the most magnificent of all caimans, with some
individuals growing to 5 m or more in length. The species is widely
distributed within the Amazon basin, and inhabits a variety of habitats,
including quiet backwaters, lagoons, lakes and rivers, and tends to
avoid strong currents.
Clutches comprise 30-60 eggs laid in a mound nest. Females remain near
the nest and may defend it against potential predators. In Ecuador the
majority of nests are laid in October, in Bolivia in September-November,
Colombia in late November-January and Brazil from mid-August-November.
Small individuals prey on small fish, amphibians and invertebrates, and
larger ones feed mainly on capybara (a large rodent) and a variety of
other larger mammals, turtles and fish. In Brazil, increasing
populations of M. niger have been implicated in some attacks on humans.
The skin of M. niger is considered to be more valuable than that of
other caiman species. There has been heavy exploitation of the species,
and the wild populations in some Range States have been greatly reduced.
Habitat loss (logging and agriculture) has also been detrimental.
However large populations still exist in some areas. For example, the
wild M. niger population in Brazil has recently been estimated to exceed
16 million individuals, and a wild harvest program has been initiated
there.
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| Common Name |
Broad-snouted Caiman |
| Scientific Name |
Caiman latirostris |
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Description |
Caiman
latirostris is a small species restricted to the southern parts of South
America, namely Argentina, Brazil, Paraguay and Bolivia. Adults are
around 1.5-2.0 m long, although some may reach 3 m. The species inhabits
marshes, lagoons and other water bodies, and is considered to be one of
the most wary crocodilians. It appears to be more tolerant of cool
climates than “tropical” species.
Nesting occurs at different times of the year depending on the region.
In Brazil it occurs between August and January, in Uruguay in January,
and in Argentina between January and March. An average of 40 eggs are
laid in a mound nest. In captivity, the male of a breeding pair has been
observed to help the female in the early stages of nest-building, but
this has not been documented from the wild. Both eggs and hatchlings are
preyed upon by a variety of predators, and large Caiman latirostris will
eat smaller ones. The diet consists of a variety of aquatic insects,
crustaceans and other invertebrates, particularly snails.
Concern has been expressed that populations are being seriously reduced
by uncontrolled hunting and habitat destruction. After Melanosuchus
niger (Black Caiman), Caiman latirostris yields the best skin of all the
southern South American caimans. A ranching program that produces skins
for the international market has been underway in Argentina for some
years – it includes the return of 10-12-month-old juveniles back to the
wild.
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| Common Name |
Cuvier’s Dwarf Caiman
|
| Scientific Name |
Paleosuchus palpebrosus |
| Common Name |
Schneider’s Smooth-fronted Caiman
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| Scientific Name |
Paleosuchus trigonatus |
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Description |
 Both
species of Dwarf caiman are widely distributed within the Amazon River
basin of South America, but do not appear to congregate in large
numbers. Males rarely grow longer than 1.7 m and females larger than 1.2
m in length, and they are perhaps the most heavily "armoured" of the
world's crocodilians, with large bone deposits in the skin. From a
commercial point of view their skin is virtually worthless, so they are
perhaps the most "secure" of living crocodilians with regard to hunting
pressure.
Both species lack the inter-orbital ridge that characterises the other
caiman species, and increased ossification of the skull and other
features give the skull a distinct angular shape.
Preferred habitat appears to be narrow jungle creeks and streams, where
they feed mainly on small mammals and invertebrates. They are rarely, if
ever seen out of water, but radio-tracking of some individuals indicated
that they leave the water at night and remain some distance away from
it, presumably to capture prey.
Another interesting feature of these species is that in the shaded
jungles of Brazil, they often construct their mound nests (10-25 eggs)
next to termite mounds, in order to gain the additional heat (produced
by the termites) to incubate their eggs.
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| Common Name |
Spectacled Caiman
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| Scientific Name |
Caiman crocodilus |
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Description |
 Spectacled
Caimans are widespread throughout Central and South America, and appear
adept at surviving in a great variety of habitats, but preferring lakes,
ponds, marshes and meandering tributaries of rivers where the current is
not fast. They are particularly abundant within some South American
countries (eg in Venezuela population estimated to exceed 3 million
individuals). Three subspecies of Caiman crocodilus are recognised (C.
c. crocodilus, C. c. apoporiensis and C. c. fuscus), but distinguishing
them from each other is not easy.
Spectacled caimans are a small crocodilian, seldom exceeding 3 m in
length. In areas where other crocodilian species (e.g. Melanosuchus
niger and Crocodylus intermedius) have been removed or reduced in
numbers, Caiman crocodilus has established itself. Feral populations now
exist in Florida (USA) and Cuba (Isle of Youth).
During the dry season, spectacled caimans can congregate in large
numbers in small pools. At such times, large caimans may prey on small
ones. At the end of the dry season, in smaller, shallow pools, they can
sometimes be found buried in the mud. Generally, little feeding occurs
during the dry season - it is a wet season activity. Caimans less than 1
m in length feed on a variety of aquatic invertebrate prey, including
crustaceans and insects. Adults also take snails and crustaceans, but
larger prey such as deer and pigs may also be taken.
Caiman crocodilus reach maturity at about 4 years of age in some areas,
and females lay an average of 30 eggs in a mound nest. The females will
remain near their nests throughout incubation, but their role in
preventing predation on the eggs is unclear - predation rates in some
areas exceed 80%. Tegu lizards are a significant predator on the eggs.
Hatching typically occurs in November, and females remain with their pod
of hatchlings for at least the first few weeks of life. However, if
water levels recede greatly, females abandon their young and set about
finding deeper water to ensure their own survival.
For 2001-2005, international trade involved an average of 612,000 C. c. fuscus and 45,000
C. c. crocodilus skins per year, mainly derived from
captive breeding in Colombia. Spectacled caimans are a species that can
bounce back quickly if hunting pressure is reduced.
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| Common Name |
Yacare Caiman
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| Scientific Name |
Caiman yacare |
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Description |
The
Yacare caiman occurs in southern Brazil, Bolivia, Paraguay and northern
Argentina. The species is morphologically and ecologically similar to
the Spectacled caiman (C. crocodilus), it was at one time considered to
be a subspecies of C. crocodilus. It inhabits in a wide variety of
habitats.
Females are mound nesters, with egg-laying (21-38 eggs) usually peaking
in the middle of the wet season. Adult males may reach up to 3 m in
length. Diet includes molluscs, crustaceans and fish.
The species is subject to ranching in Argentina and wild harvest in
Brazil, Paraguay and Bolivia.
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| Crocodiles |
| Common Name |
African Slender-snouted Crocodile |
| Scientific Name |
Crocodylus cataphractus |
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Description |
 The
African Slender-snouted Crocodile has a narrow snout, and closely
resembles the Australian Freshwater crocodile (C. johnstoni). The
species is restricted to Central and West Africa (Angola, Benin, Burkina
Faso, Cameroon, Central African Republic, Chad, Congo, Cote d’Ivoire,
Democratic Republic of Congo, Equatorial Guinea, Gabon, Gambia, Ghana,
Guinea, Guinea Bissau, Liberia, Mali, Mauritania, Nigeria, Senegal,
Sierra Leone, Tanzania, Togo, Zambia) and until recently, was one of the
least known crocodilians. They are rarely found in abundance, and the
maximum size attained is thought to be about 4 m, with average adult
sizes of 2-2.5 m. Although the slender snout suggests fish-eating
habits, a variety of other prey such as crustaceans, crabs, insects,
frogs and snakes are also taken.
Like the Dwarf caimans of South America, C. cataphractus nest in
rainforest beside small streams and rivers. The dense vegetation canopy
prevents direct sunlight reaching the nests, and fermentation of the
nest material helps maintain nest temperatures within acceptable limits
for survival. Egg-laying (13-27 eggs) takes place in April, and
incubation takes 90-100 days. It appears that varanid lizards are
predators on the eggs, although the levels of predation are unknown.
Hatchlings appear in July, which coincides with the beginning of the wet
season.
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| Common Name |
American Crocodile
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| Scientific Name |
Crocodylus
acutus |
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Description |
 The
American Crocodile is another widely distributed species. It extends
from a relict population in Florid (USA), through the Caribbean Islands
and along the coast of Central America to the northern coast of South
America. Throughout much of this range numbers have been greatly
reduced, although significant populations still occur in Haiti, the
Dominican Republic and Cuba. It occupies coastal habitats such as
mangrove swamps and brackish bays, large lakes, and may extend well
upstream in coastal rivers. American crocodiles are capable of moving
considerable distances, and some individuals that have strayed out of
their normal range have been found in the Cayman Islands and Trinidad.
The species is a moderately sized crocodilian that can at times exceed 4
m in length. Females lay appear to be primarily a hole-nester, although
in Florida both hole and mound nests may be used. Females appear to
return to the same nesting site each year, and are thought to reach
sexual maturity at about 2.5 m in length.
Adults remain in dens near the nests, burrowing up to 9 m into creek
banks. Eggs are typically laid in April-May, and hatchlings emerge in
July-August. However, timing of nesting does vary geographically. For
example, in Colombia, populations in different parts of the country nest
at different times of the year, due to climatic differences between the
areas. In Florida, predation on eggs and hatchlings by raccoons is
significant, and recruitment into the population is low. In other areas
of its distribution, numbers have been reduced due to hunting and
habitat loss.
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| Common Name |
Australian Freshwater Crocodile
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| Scientific Name |
Crocodylus
johnstoni |
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Description |
 The Australian Freshwater Crocodile or Johnston's River crocodile is
endemic to mainland Australia. It is a small species, seldom exceeding 3
m, with a narrow snout resembling that of Tomistoma. The species was
hunted for its skin up to the early 1970s, but has now largely recovered
from the effects of past hunting. The full impact of introduced cane
toads (Bufo marinus) on wild C. johnstoni populations is
not known, but adult and juvenile mortalities (as high as 77%) have been
reported in areas once the toads arrive. The species is known to be more
susceptible to cane toad toxin than the Saltwater crocodile (C.
porosus).
 Nesting occurs during the dry season (August-September), with clutch
sizes averaging 13 eggs. Eggs are laid in a hole nest dug in friable
substrates, and females do not guard their nests/eggs. Hatching occurs
in November-December, before wet season rains begin. Prior to
colonisation by introduced cane toads (Bufo marinus), egg
mortality was high (<90-95%), mainly the result of predation by goannas
(monitor lizards). In one area where data are available, egg mortality
has now decreased to <50%, and hatchling recruitment has increased by
400% or more, as goanna numbers were greatly reduced by the arrival of
toads.
Like other crocodilians, individual growth rates vary considerably.
During the dry season “freshies” eat little, and annual growth takes
place during the wet season when food is more plentiful. Diet consists
mainly of fish, although other prey area also taken (eg mammals,
reptiles, amphibians, insects). Freshwater crocodiles inhabit a variety
of freshwater habitats, and may occur in very high densities in isolated
billabongs (pools) during the dry season. In many rivers Freshwater
crocodiles are sympatric with the larger Saltwater crocodile.
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| Common Name |
Cuban Crocodile |
| Scientific Name |
Crocodylus
rhombifer |
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Description |
The
Cuban Crocodile is endemic to Cuba. It is restricted to Zapata Swamp on
the mainland, and Lanier Swamp on the Isle of Youth (previously named
Isle of Pines). In 1959-60 several hundred adult C. rhombifer were
translocated to enclosures within Zapata Swamp, when they were under
threat from agricultural development. The development did not go ahead,
but the crocodiles remained within the enclosures, where they mixed with
Crocodylus acutus. The two species interbreed, and pure-bred C. rhombifer are now outnumbered by hybrids.
Hybridisation also occurs naturally in the wild population. Some C. rhombifer were transported to Vietnam and later to Cambodia, and
hybridisation has occurred with the Siamese crocodile (C. siamensis) in
both countries.
 The population of C. rhombifer on the Isle of Youth may be threatened by
the establishment of the introduced caiman, Caiman crocodilus fuscus.
Conservation efforts have seen C. rhombifer reintroduced into habitats
there.
Few ecological data are available for C. rhombifer. It is a
medium-sized, hole-nesting crocodile, which feeds on fish, turtles and
small mammals.
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| Common Name |
Dwarf Crocodile
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| Scientific Name |
Osteolaemus
tetraspis |
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Description |
 The
Dwarf Crocodile is restricted to Central and West Africa (Angola, Benin,
Burkina Faso, Cameroon, Central African Republic, Congo, Cote d’Ivoire,
Dem. Rep. Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea,
Guinea-Bissau, Liberia, Mali, Nigeria, Senegal, Sierra Leone, Togo), and
its biology and ecology are very poorly known. It rarely exceeds 2 m in
length - average adult size is 1.0-1.5 m. In appearance, it resembles
the dwarf caimans of South America, but it is of course in a totally
different subfamily.
It is a nocturnal species, and is rarely seen during the day. Generally
docile and timid in nature,
 Dwarf crocodiles do not congregate in large
numbers, and are usually solitary. They are associated with tropical
rainforests, and tend to avoid large watercourses. Frogs, fish and crabs
are the major prey items. In captivity, females lay 11-17 eggs in a
mound nest around June-July. Large osteoderms in the skin, nocturnal
habits and small size have saved the species from the intense
exploitation that Crocodylus niloticus has suffered, though some hunting
still occurs, mainly for meat.
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| Common Name |
Morelet’s Crocodile
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| Scientific Name |
Crocodylus moreletii |
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Description |
 Crocodylus
moreletii occurs on the Atlantic regions of Central America (Mexico,
Belize, Guatemala). It rarely exceeds 3 m in length, and typically
inhabits freshwater lagoons, streams and swamps, and sometimes rivers.
In the dry season individuals sometimes burrow into mud banks, to wait
for the wet season.
Females lay their eggs (20-45) in a mound nest, usually a few metres
from water, although some nests are constructed on floating rafts of
vegetation. In Mexico nesting occurs in April-June. Hatchlings are about
17 cm long when they hatch, and are guarded by the female for a time.
The belly skin of C. moreletii lacks osteoderms, so it has been
intensively hunted for its skin. Habitat modification is also a threat,
particularly when it allows hunters access to crocodile refuges.
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| Common Name |
Mugger Crocodile |
| Scientific Name |
Crocodylus
palustris |
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Description |
The
Mugger is perhaps the most "broad-snouted" of the "true" crocodiles. The
species is found in India, Pakistan and Iran, and is quite abundant in
Sri Lanka where they occur in the numerous man-made lakes there.
Although some individuals may reach 5 m in length, they do not generally
exceed 3-4 m. They prefer fresh, still waters, with depths between 3 and
5 m, but are sometimes found in brackish water. In the summer and winter
months they burrow into pond and riverbanks to escape hot and cold
conditions respectively. In some cases these burrows may be up to 10 m
long. The diet consists of a variety of invertebrates, fish and birds.
In captivity, female C. palustris start laying eggs when they are
1.7-2.0 m long, and 6 years of age. Males are sexually mature at 2.6 m
and 10 years of age. In the wild, individuals do not grow as fast as
those in captivity, and so they are probably older when they reach
sexual maturity. Females lay in their eggs in sandbanks, between
February and April, and hatching occurs between April and June. One of
the unique features of muggers is that they appear to be the only
species of living crocodilian that regularly breeds twice in any one
year, with different clutches being laid between 30 and 57 days apart.
This may be related to the two monsoonal influences that occur in Sri
Lanka and southern India each year.
Mongoose, jackals and monitor lizards are predators on the eggs, and
herons and storks eat hatchlings. Further egg mortality may be caused by
flooding and dessication. As with the other species of crocodilian in
India, the pressures of a large human population, and hunting in the
past, reduced the numbers of C. palustris. In India, wild mugger
populations have been boosted by a conservation program involving the
restocking of depleted rivers with juveniles raised in captivity.
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| Common Name |
New Guinea Freshwater Crocodile |
| Scientific Name |
Crocodylus novaeguineae |
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Description |
 Crocodylus
novaeguineae is widely distributed in Papua New Guinea and Papua
Province (Indonesia), where it occupies vast areas of heavily vegetated
freshwater swamp. Despite continual hunting for decades, there seems no
possibility of extinction. In both Papua New Guinea and Indonesia a
limit on the size of skin (51 cm belly width) that could be exported is
imposed, to protect the adult portion of the population from hunting.
Landowners collect juveniles and sell them to traders who pass them on
to crocodile farms. Selling a few crocodiles may provide the entire cash
income for people in remote rural areas. An egg harvest program was also
initiated in the Sepik River area of Papua New Guinea, with income also
being generated from the sale of these eggs. The benefits of selling the
eggs to a crocodile farm are much greater than raiding the nests (for
food), and a further incentive is placed on not killing the breeding
females. In order to compensate the people for the loss of animal
protein from eating the eggs, landowners are also given chicken eggs
together with cash payment.
The New Guinea Freshwater crocodile is a mound-nesting species, with
females becoming sexually mature at 1.8-2.0 m in length, and males at
2.0-2.5 m. Maximum adult size is 3 m for females and 3.5 m for males.
Generally, females do not protect their nests, and will retreat quickly
when approached, a behaviour that may be due to the regular visits by
landowners to collect eggs. Besides human predation, eggs are lost to
flooding. The northern population of C. novaeguineae nests in the dry
season, and has an average clutch size of 35 eggs. The southern
population nests mainly in the wet season, with an average clutch size
of 22 eggs. This suggests that there may be two distinct "types" of
C. novaeguineae in Papua New Guinea - one in the north and one in the
south.
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| Common Name |
Nile Crocodile
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| Scientific Name |
Crocodylus
niloticus |
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Description |
 The
Nile crocodile is the crocodilian species featured in many of the Tarzan
movies. It is a large crocodile, with adult males commonly exceeding 4 m
in length. It is a gregarious species, and so it is not uncommon to see
large numbers lying side by side on riverbanks. The species is widely
distributed in Africa (Angola, Benin, Botswana, Burkina Faso, Burundi,
Cameroon, Central African Republic, Chad, Congo, Cote d’Ivoire,
Democratic Republic of Congo, Egypt, Eritrea, Ethiopia, Equatorial
Guinea, Gabon, Gambia, Ghana, Guinea, Guinea Bissau, Kenya, Liberia,
Madagascar, Malawi, Mali, Mozambique, Mauritania, Namibia, Niger,
Nigeria, Rwanda, Senegal, Sierra Leone, Somalia, South Africa, Sudan,
Swaziland, Tanzania, Togo, Uganda, Zambia, Zimbabwe) and is a species
upon which a considerable research effort has been expended. Its skin is
highly prized for fashion leather.
Nesting takes place in the dry season (September), with females digging
a hole-type nest next to permanent water, and laying an average of 60
eggs. The female attends the nest, and may defend it against predators.
Even so, there is still high egg mortality due to predators, mainly
varanid lizards and mammals. Hatchlings also experience a high
mortality. Because of these losses, eggs are collected and incubated by
crocodile farmers each year, to provide stock for their farms. These
ranching programs appear to have had little impact on the size of the
wild populations, and provide economic incentives for the long-term
conservation of crocodiles.
Like other crocodilians, the Nile crocodile is an opportunistic feeder.
Insects are the main food of young crocodiles, but as they increase in
size, so to do the prey on which they feed. Nile crocodiles are
responsible for more human deaths than any other crocodilian. For
example, in Zimbabwe crocodiles are responsible for more human
fatalities than all the other wild animals combined, and many more
deaths occur in other African countries (eg Tanzania) where the limited
water available in the dry season must suffice for both people and
crocodiles. The Crocodile Specialist Group’s Human-Crocodile Conflict
Working Group currently monitors crocodile attacks on humans and
livestock in Africa.
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| Common Name |
Orinoco Crocodile |
| Scientific Name |
Crocodylus
intermedius |
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Description |
 The
Orinoco Crocodile is restricted to the Orinoco River drainage in
Venezuela and Colombia. Historically distributed in a variety habitats,
it reached its greatest numbers in rivers of the Llanos region of
Venezuela. As a result of uncontrolled hunting for skins (1920s-40s),
numbers of Crocodylus intermedius were greatly reduced. However, a
determined conservation effort in Venezuela, based on ranching of eggs
and subsequent release of juveniles back into the wild, has seen the
wild population increase significantly from low levels 30 years ago.
In January-February, the end of the dry season, females lay 15-70 eggs
in a hole-nest in sandbars and riverbanks. Hatchlings emerge just before
the wet season.
 The main diet of young individuals is insects, crabs,
snails and other invertebrates and adults feed mainly on fish, mammals
and birds.
Large male C. intermedius may exceed 4-5 m in length and one specimen
was reputed to have reached nearly 7 m. As a large crocodilian the
Orinoco crocodile is often viewed as a threat to people and livestock.
However, attacks on people have rarely, if ever, been reported.
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| Common Name |
Philippine Crocodile |
| Scientific Name |
Crocodylus
mindorensis |
|
Description |
 Previously
widely distributed throughout the Philippines, Crocodylus mindorensis
now occurs Mindanao, Negros and Luzon. Initial decline in numbers was
due to hunting, but now habitat modification is the major threat to
existing populations. Although no definitive population estimates are
available, the total wild population is believed to be small (perhaps
<100 non-hatchlings). Some captive breeding is being carried out, and a
program is now in place to establish protected areas where C.
mindorensis can be released back into the wild.
Adults rarely exceed 2-3 m, and only the largest males sometimes reach 4
m in length. Clutch size is small (7-20 eggs), which is laid in a mound
nest during the dry season.
Until recently, the species was considered to be a subspecies of the New
Guinea Freshwater Crocodile (C. novaeguineae).
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| Common Name |
Saltwater Crocodile
|
| Scientific Name |
Crocodylus
porosus |
|
Description |
 The Saltwater or Estuarine crocodile is the largest of all crocodilians,
which makes it a good contender for the largest living reptile on earth.
The normal maximum size of adult males is 5 to 6 m long, with some
individuals reaching 7 m. There are reports of three specimens reaching
8 to 10 m, but there are no "parts" of the animals in existence with
which to substantiate the claims.
Saltwater crocodiles are distributed from Sri Lanka and the east coast
of India in the west, to the Caroline Islands in the east, from Burma
and Southeast Asia in the north, to Australia in the south. They live in
tidal and freshwater rivers and swamps, and often travel around the
coastline.
In the wild, males mature at around 3.1 m (17 years), and females at
around 2.1 m (12 years). Females nest in the wet season (October-May in
northern Australia), laying an average of 50 eggs in a mound nest.
Interestingly, in Papua New Guinea mean clutch size is higher than in
Australia, but the eggs are smaller – total clutch mass is similar in
both areas. Females actively guard their nests, and non-human predation
on eggs is negligible. However, mortality due to flooding and
overheating is high (mean= <80%), and in some areas 100% of eggs may be
lost to environmental factors.
 Saltwater crocodiles tend to eat even in the cooler times of the year,
and anything that can be overpowered may be taken, including livestock
(horses, cattle, buffalo, pigs) and even humans. In the Northern
Territory, a “problem crocodile” program results in around 240 Saltwater
crocodiles being removed annually from Darwin harbor, to improve public
safety. The size structure of the population in the Northern Territory
is skewed towards a higher proportion of larger individuals, and
research indicates that numbers of small crocodiles are dependent on the
numbers of large crocodiles.
The skin of Saltwater crocodiles is the most prized of all crocodilian
skins for fashion leather. In Australia sustainable use programs operate
in the Northern Territory and Western Australia, based largely on
harvesting of eggs and subsequent rearing of hatchlings on farms. In
Papua New Guinea an egg and juvenile ranching program also exists, and
there is a wild harvest of wild animals. In Papua Province, Indonesia,
ranching of hatchlings and juveniles occurs, as well as a wild harvest.
In other parts of the species’ range, wild populations are depleted, and
trade relies on closed cycle captive breeding (eg Malaysia, Singapore,
Thailand, Vietnam).
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| Common Name |
Siamese Crocodile |
| Scientific Name |
Crocodylus
siamensis |
|
Description |
 The
Siamese Crocodile was once reasonably abundant in the freshwater swamps
of Thailand, as well as parts of Vietnam, Cambodia, parts of the Malay
Peninsula and Indonesia. However, the wild populations have been reduced
to a remnant, mainly by hunting in the 1940s – wild populations are now
known from Cambodia and Indonesia (Kalimantan) The populations in
Vietnam and Thailand are considered to be extinct, and reintroduction
programs are underway there (Pang
Sida and Cat Tien National Parks
respectively). There are large numbers of C. siamensis in captivity in
Cambodia, Thailand and Vietnam. Hybridisation
 occurs between C. siamensis and
C. porosus and C. rhombifer. Hybrids produced tend to grow
faster, produce larger clutches and larger skins, and so hybridisation
is actually encouraged.
Male Siamese crocodiles may reach lengths of 3-4 m. In captivity, sexual
maturity is reached after 10-12 years, and eggs are laid in April-May,
in a mound nest.
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| Common Name |
Tomistoma
(False Gharial)
|
| Scientific Name |
Tomistoma
schlegelii |
|
Description |
 The
Tomistoma resembles the Indian Gharial in that it has
a long, slender snout. It is predominantly a fish-eater, although other
larger prey may also be taken. The species is found in the
Malaysian-Indonesian region (Malaysia, Indonesia), where wild
populations have been greatly reduced - it is extinct in Thailand and
Peninsular Malaysia. Until recently, little was known of the biology and
ecology of the Tomistoma.
Females mature at around 2.5-3.0 m in length (5-6 years of age), and are
mound-nesters. Between 20 and 60 eggs are laid in the dry season, and
hatchlings appear after 2.5-3 months, at the beginning of the wet
season. Lizards and wild pigs are predators on the eggs, which are the
largest of all the crocodilian species.
 There are large numbers of Tomistoma in captivity, but they have
rarely bred in captivity, which is unusual - most crocodilians breed
well once they settle into captive situations. One farm in Thailand is
consistently producing hatchlings and one farm in Sarawak has produced
some hatchlings, but overall there are still many individuals that
simply do not breed.
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| Gharial |
| Common Name |
Indian Gharial |
| Scientific Name |
Gavialis
gangeticus |
|
Description |
 Gavialis
gangeticus, the Indian Gharial, is a member of the subfamily Gavialinae.
Other than its long snout, its most unusual and distinctive feature is
the bulbous protuberance on the snout of adult males. It is from this
structure that the word gharial originated - from the Hindu "ghara"
meaning "pot". The species is sometimes called a "gavial", but this is
incorrect and the use of that name has been largely abandoned.
Gharials occurred historically in India, Pakistan, Myanmar, Bhutan and
Nepal, where inhabited rivers and hill streams. However, due to the
pressures of an enormous human population, loss of habitat and hunting
for skins, the gharial populations declined in numbers. Today, wild
gharial populations exist in India (Chambal, Son, Ken and Mahanadi
Rivers; Katerniaghat Wildlife Sanctuary) and Nepal (Rapti-Narayani,
Karnali, Babai and Koshi Rivers).
 Successful restocking programs in India and Nepal saw wild gharial
populations increase, but over the last 10 years the wild populations
have again declined, as a result of various factors (eg netting, habitat
alteration). As a consequence, the species was recently (2007) listed as
“Critically Endangered” on the IUCN Red List of Threatened Species, and
the global population is estimated to contain around 200 adults.
Mating occurs in December-January, and nesting in March-April. Females
lay an average of 40 eggs (range 6-95) in a hole nest in sandy
substrates on mid-river sandbars and river banks. Known predators on the
nests are rats and jackals, and wild pigs and monitor lizards are also
suspected.
 Male gharials mature at about 3 metres total length, and some may grow
to large sizes (eg exceeding 6 m). Fish appear to be the main food,
although they eat insects, frogs and a variety of other small animals.
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