玳瑁

Hawksbills may take decades to mature and it could be between 20 to 40 years before they are ready to breed (10). Upon reaching sexual maturity, a female will typically lay up to five clutches of around 100 to 140 eggs in one breeding season, and then wait a few years before nesting again (6). Nesting is much more dispersed than in other marine turtles, but individuals do tend to return to a particular beach season after season (10). Having survived the dash to the sea, hatchlings are believed to spend their first few years in the open ocean before returning to more sheltered coastal waters. Recent studies indicate that the oceanic phase may be shorter for hawksbills, or even omitted in certain regions, as hatchlings swim less vigorously than those of other species (7). Probably less than one out of 1000 eggs will survive and reach adulthood (10). Adults are opportunistic predators, using their sharp beak to prize invertebrate prey from crevices within the reef. Unusually amongst marine animals (to whom they are often unpalatable), sponges make up the majority of the hawksbill's diet (6).

International trade in the hawksbill turtle is banned amongst signatory nations by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (3), but extensive illegal trafficking still occurs between CITES signatories and among other nations. Preventing this black market trade is the key to saving this species and TRAFFIC (the wildlife trade monitoring arm of WWF and IUCN-World Conservation Union) is involved in monitoring and highlighting this problem (13). In 1988, the government of the Seychelles took a very public stand against tortoiseshell trade by burning a stockpile of seized shells (4), in a manner reminiscent of burning ivory pyres in Kenya. Action to save the world's turtles is being taken by many international bodies and recent increases in hawksbill nesting populations have been observed at a few well-protected sites (10). With successful monitoring of populations and a decrease in illegal trade, the hawksbill may respond well to long-term protection.

This Critically Endangered marine turtle has been exploited for thousands of years as the sole source of commercial tortoiseshell. The beautiful carapace is generally streaked and marbled with amber, yellow or brown and often has a strongly serrated edge (5). Unlike other species, the scales (or scutes) of the carapace overlap. The narrow head and strongly hooked beak give rise to this turtle's common name (6), while the imbricate nature of the (overlapping) scutes give rise to the Latin species name of 'imbricata' (7).

Adult hawksbill turtles are mainly associated with the clear, relatively shallow water of coastal reefs, bays, estuaries and lagoons, with nesting generally occurring on remote, isolated sandy beaches (6) (9).

Hawksbill turtles are found throughout the world in tropical waters and are known to nest on beaches in at least 60 countries (8). Recent evidence indicates that hawksbills take part in long distance migrations with breeding and feeding grounds in very different locations (5), although they tend to be more sedentary (move less) than other sea turtles species.

Classified as Critically Endangered (CR) on the ICUN Red List 2007 (1). Listed on Appendix I of CITES (3), and Appendix I of the Convention on Migratory Species (CMS or Bonn Convention) (4).

Global numbers are very difficult to estimate but it appears that this turtle has suffered drastic decline, probably by as much as 80 percent over the last century (1) (8). Major threats to survival come from illegal trade in the turtle's prized shell, known as tortoiseshell, which has been sought for jewellery and ornaments for centuries. There is also a substantial market for eggs, meat and even stuffed juveniles as exotic gifts in some parts of the world (11). Additional pressure on the global population comes from harvests to support traditional customs, the loss of nesting sites, accidental entanglement in fishing lines and the deterioration of coral reef systems which act as feeding sites for these turtles (12).