A Hawksbill turtle swims along the reef edge

Although in life they can be covered in algae, Hawksbill turtles have beautifully coloured scales, or scutes, on their shells

Like other sea turtles, Hawksbills can rest for long periods underwater without surfacing

Australia now has what is thought to be the last remaining large nesting population of Hawksbill turtles in the world

Sponges are the main food of Hawksbill turtles

Sea cucumbers are eaten by Hawksbill turtles

Poor water quality threatens turtle food resources

Hawksbill Turtles

Hawksbill turtles (Eretmochelys imbricata), are air breathing reptiles, one of the world’s seven species of sea turtle. They feed on a wide range of marine invertebrates and some algae.

'Hawksbill'

The common name 'Hawksbill' turtle comes from their distinctive beak-like mouth, which looks like the beak of a bird of prey. They use this 'beak' to prise attached animals and algae from reef crevices.

They have thick, overlapping scales on their shell with very beautiful amber, brown and black patterns.

Remarkable armour

Sea turtles evolved about 150 million years ago, in the age of the Dinosaurs, and their body design has been so successful that they have changed little since then.

Hawksbill turtles have broad, flattened ribs that are joined to each other and are fused to the spine, and a broad bony plate under their bodies, producing a bony case that completely encloses everything except the turtle’s limbs and head. The internationally respected biologist Dr Alfred Sherwood Romer wrote in 1933:

'Because they are still living, turtles are commonplace objects to us; were they extinct, their shells - the most remarkable armour ever assumed by a tetrapod (4 legged) animal – would be a cause for wonder.'

This protective case has served them well, as adult sea turtles have relatively few predators, apart from sharks, crocodiles and humans. It also allows Hawksbill turtles to move safely amongst sharp corals and reef rock.

Traditional hunting

Hawksbill turtles are hunted for their shell and meat, and their eggs are harvested. Some Hawksbill turtles build up toxins from their diet in their meat; there have been illnesses and deaths reported after eating Hawksbill meat, although they are still hunted for food.

Turtle eggs and meat have been a traditional food for Aboriginal and Torres Strait Islander people for thousands of years. Turtle shell is used to make fish-hooks and decorations

All harvesting of turtles and their eggs has been banned in Queensland since 1968, apart from Aboriginal and Torres Strait Islander traditional hunting.

The 'tortoiseshell' industry

Hawksbill turtles have very colourful, thick scales, or 'scutes' on their shell which were carved and polished to make ornaments, glasses frames and jewellery. The raw material used to make these products is called 'bekko'. Hawksbill turtle skin was used for leather and preserved whole turtles and shells were sold as souvenirs.

The high value of tortoiseshell made Hawksbills the target of unsustainable levels of hunting. Their numbers were so severely depleted that they are now on the IUCN Red List as Critically Endangered.

The tortoiseshell trade in Australian waters goes back to Malay traders in the 17th century; Europeans began exporting tortoiseshell in the late 1700s. At its peak between about 1895 and 1909, more than 1000 turtles were taken from northern Australia each year.

The Australian tortoiseshell harvest largely ended in the 1930s, and was made illegal when Hawksbill turtles were declared a protected species in Australia in 1968. Thanks to the early closure of this industry, Australia now has what is thought to be the last remaining large nesting population of Hawksbill turtles in the world.

It is thought that the pre-harvest southwest Pacific nesting population of Hawksbills must have been enormous to support the level of harvesting that has occurred in the past: it could never support this level of hunting now.

Trade in turtle shell and all turtle products is now illegal in Australia and most overseas countries.

Turtles and tourism

‘Turtle riding’ both as the turtles came up the beach to lay their eggs, and in the water, was promoted as a popular part of Great Barrier Reef tourism until about the 1950s.

Later on, as more was learned about the lives of sea turtles and they became more scarce, these harmful and stressful interactions went out of fashion and people looked for less intrusive and stressful ways of interacting with turtles.

Turtles are now protected on the Great Barrier Reef and visitors watch turtles behaving naturally in the wild, through programs like the Turtle Research program at Mon Repos, near Bundaberg, or at the Turtle Hospital at Reef HQ Aquarium in Townsville.

Turtle biology

Hawksbill turtles are a relatively small sea turtle, growing up to around 80cm shell length and weighing up to 50kg. Females grow larger than males. They are very slow growing and may live for 80 years or more.

As air-breathing reptiles, they must surface regularly to breathe; the length of time that they can stay submerged depends on their levels of stress and activity. While they are actively feeding they will stay underwater for around 4-5 minutes between surfacing for breaths, but they can also sleep underwater for up to several hours without surfacing.

Sea turtles don’t need to drink fresh water because they can get rid of the excess salt from seawater through special ducts next to their eyes. When females are ashore laying eggs the salty secretion looks like tears.

During their long migrations, sea turtles sense the strength and angle of the earth’s magnetic field, which varies depending on your position on the earth, allowing them to navigate across the sea.

Various meat & some veg...

Adult hawksbill turtles feed on invertebrate animals, mainly sponges, but also soft corals, shells, sea squirts, sea cucumbers, seagrasses and algae. Hatchlings are omnivorous and will eat whatever they can find at the water's surface.

Global citizens

The lifestyle of sea turtles makes them truly global citizens: as they move through their life cycle they are dependant on completely different habitats, hundreds or even thousands of kilometres apart, and often in different countries. They nest in about 60 countries.

Their habitats are in tropical and subtropical waters of the Pacific, Indian and Altantic oceans.

Tagging studies have shown that Hawksbill turtles nesting on Milman Island, off the northern Great Barrier reef, migrated from the southern Gulf of Carpentaria, southeastern Indonesia, southern Papua New Guinea and the northern GBR.

Hawksbill Turtles in Australia

Hawksbill turtles nest mainly in low densities, although there is one high-density nesting site at Milman Island on the northern GBR.

Hawksbill turtle nesting areas in Australia are the offshore islands and cays north of Princess Charlotte Bay in the northern Great Barrier Reef (GBR) and Torres Strait Islands, Arnhem Land and Western Australia north of Shark Bay. These areas are globally significant as hunting has severely reduced many populations in other parts of the world.

Feeding areas extend from northern Western Australia, across to Torres Strait and right down the east coast to northern NSW.

Small numbers of Hawksbill turtles feed on the fringing and mid-shelf reefs of the Whitsunday region.

Home bodies & great travellers

Hawksbill turtles that hatch in the northern Great Barrier Reef disappear into the Pacific Ocean gyre, returning when they are between 5 and 7 years old. After these so-called 'lost years' when they are rarely seen, they return to a shallow rocky or coral reef and set up home.

Once young turtles settle on a good spot to feed they can remain in the same area for decades, even using exactly the same spot to sleep every night.

Life begins at 30?

Once they reach breeding age at around 30 years old, Hawksbill turtles get itchy feet again, migrating many hundreds of kilometres to breed, every 2-5 years. The frequency of breeding varies because their breeding cycles are tuned in to the sea surface temperature in their feeding grounds.

Males and females return to breed at beaches in the region where they hatched, where the females go ashore to lay their eggs.

Making more turtles

Hawksbill turtles gather to mate off their nesting beaches between November and February in the northern Great Barrier Reef, although breeding can occur year-round.

Males hang around in the waters off the nesting beaches, waiting for a chance to mate with the females, who will store sperm from multiple males to fertilise each batch of eggs. After mating the male's work is done and they depart for their feeding areas.

The female's work has only just begun: they then come ashore on island and mainland beaches to nest. Breeding is year round, nesting peaks in January to February on the GBR and in the Torres Strait. Most hatchlings emerge between February and April. Females return every 2 weeks until they have laid 2 to 3 clutches of around 122 small, round eggs.

Not all beaches are created equal

Not every beach is right for nesting: for hatchlings to develop, the sand of the nesting beach must be well aerated, protected from flooding by tides or creeks, free of disturbance from storms and egg predators, not too salty, moist but not too wet, and between 25-33˚ C.

The sex of hatchlings depends on the temperature of the sand that the eggs are buried in: boys are cool (all boys at or below 26˚ C) and girls are hot (all girls at or above 29˚ C). Nests with a range of temperatures in between produce a mixture of both sexes.

'Survivor', turtle style

Hatchlings take around 64 days to develop and usually emerge en-mass, at dusk or at night, using their numbers and the cover of darkness to increase their chances of avoiding predators. Even so, large numbers fall prey to birds and crabs, and many more to fish, during their race for the open sea. As they emerge and cross the beach, they somehow imprint chemical and positional information about where they are, so that can return as adults to breed.

Hatchlings are strongly attracted to light that is low on the horizon, which would normally be light reflected from the sea and would attract them seawards. This instinct can get them into trouble when we put artificial lighting along shorelines, attracting them inland to a sticky end on roads or on the menu of suburban pets. Offshore lighting at resorts, port facilities and large-ship anchorages also attracts hatchlings and makes them vulnerable to bird predation.

Fuelled by the yolk sac which they swallow before hatching, hatchlings swim perpendicular to the waves for up to 2 weeks without feeding, towards the open sea, where there are less predators. Those that make it will then enter the deep ocean gyres, where they are thought to spend the next five years or so floating at the surface in drift-lines of flotsam and drifting Sargassum sp. seaweed. During this stage of their lives they are carnivorous, eating whatever small animals they come across floating on the surface. Possibly less than 1 in 1000 will make it back to the reefs.

Turtles in trouble

Green turtles face numerous threats to their survival, including:

Disturbance during nesting from people, pets, vehicles and lights near nesting beaches
Loss of feeding habitat due to poor water quality
Entanglement in, and ingestion of marine debris, especially plastics
Discarded fishing gear ('Ghost nets') and shark control nets trap and drown turtles
Turtles are accidentally caught in some fisheries, although measures to minimise by-catch of turtles, such as Turtle Excluder Devices in trawl nets, are mandatory on the Great Barrier Reef. Hawksbills are also bycatch in long-line fisheries
Introduced species such as feral pigs and dogs which dig up nests and eat turtle eggs
Boats travelling fast through shallow seagrass areas which can hit and injure or kill turtles
Climate change threatens turtles by changing the sea surface temperature, disrupting breeding cycles, and altering sand temperatures on nesting beaches, disrupting the sex ratios of hatchlings
Changes in sea level and storm frequency due to climate change threaten the reef habitats that Hawksbill turtles depend on for food
During their breeding migration, particularly in their nesting areas of northern Vanuatu, the Solomon Islands and eastern Papua New Guinea, hunting for tortoiseshell and meat and the harvesting of eggs remain threats to Hawksbill turtles

How you can help Hawksbill turtles...

Go slow for those below!! Sea turtles feed in shallow inshore waters: slow your boat speed and keep a good lookout to avoid striking turtles. If you can, travel at speed in deeper water, where there is less turtle activity
Report stranded or dead sea turtles: call the marine Animal Stranding Hotline at RSPCA Qld 1300 ANIMAL (1300 264625)
Avoid disturbing turtles on beaches during the nesting season and avoid using lights that might frighten females laying eggs or cause hatchlings to head inland
Keep your dog under control on the beach during turtle nesting season
Don’t drive vehicles in the dunes where turtles nest
Support local programs to restore and protect turtle nesting and feeding habitat
Support local programs to control feral animal pests
Avoid littering the marine environment: pick up litter when you visit the beach, even if it isn’t yours!
Water quality begins at home (and at work...)! Remember that the chemicals you use will ultimately end up in the sea. Use environmentally friendly chemicals; avoid artificial herbicides and pesticides if you can. If you have to use harmful chemicals, follow the instructions on the label carefully and avoid uses that might let chemicals wash into drains or waterways.
Buy turtle-friendly seafood products: Australian prawn fishermen use turtle excluder devices on their trawl nets
Check your crab pots regularly: turtles die when they become entangled in poorly designed or abandoned crab pots
When you travel, don’t buy souvenirs made from turtles
Support programs that conserve turtles in developing countries