Threat and impacts

The population and conservation status for all 23 species of crocodilian vary greatly, with some species pushed to the brink of extinction and other species recovering from those threats they were facing.

The following is a summary of the main threats to crocodiles:

Habitat loss

The most critical threat facing threatened crocodiles is the loss and fragmentation of natural habitats.

The loss of swamps, marshes, wetlands and other natural systems into agriculture, mines, and urban developments, the draining of swamps and other wetlands, and deforestation and clearcutting reduce potential habitat for many species.

In addition the remaining patches of habitat are are often too small and fragmented for species to survive. This problem is exacerbated by the construction of roads or other such barriers that cause populations in these fragmented islands to become vulnerable to localised extinction. In addition many crocodile species have limited dispersal ability and cannot easily occupy unsuitable habitat.

Habitat destruction has been implicated in the decline of many crocodilian species, including the Chinese alligator and Cuban crocodile.

Hunting and exploitation

Humans have exploited crocodiles for a very long time, and sometimes this exploitation has resulted in population crashes.

Indigenous peoples have used crocodile hides for thousands of years with little impact on populations. The dangerous levels of exploitation came with the rise in demand for crocodile leather in European countries.

An estimated ten million alligators were killed between 1870 and 1970. Up until recently, an estimated million caimans were killed illegally every year to make crocodile leather products.

Although hunting was restricted in the 1940's, numbers continued to decline from illegal poaching. Only recently with the monitoring and enforcement of hunting regulations have wild populations started to recover.

Hybridisation

Hybridisation may also endanger crocodiles, damaging the genetic variation within a species. For example, the Siamese crocodile has been often reported hybridising with the Saltwater crocodile, which saw wild populations decline dramatically.

Captive hybrids are particularly common and breeding programmes often produce hybrids that may be accidentally or intentionally introduced into the wild.

Persecution and trophy hunting

People have long considered crocodiles vermin or a dangerous nuisance. For this reason, crocodiles have been hunted to extinction in some places, particularly as cattle ranching encroaches on crocodile habitat. The American alligator was targeted as a problem animal and wiped out in many areas in the southern United States.

After European colonization of Africa, the governments of many countries paid a high bounty for every crocodile killed in order to make the countryside safer for people and grazing cattle. The large Nile crocodiles were also sought after as sport trophies for hunters on safari.

Other threats

Crocodiles face a number of other threats:

Collection for the exotic pet trade has reduced population densities in local areas of some countries.

Pollution associated with gold and precious metal mining activities is a major threat to some caiman species.