It’s almost 100% predation.
Waru, why you? …because…
Australia’s own, the flat-back turtle, is under threat of annihilation.
They have survived for millions of years. Their eggs are a touch bigger than golf balls. Their young are the largest hatchlings of any turtle. They carry shields that grant no defense against the barrage of predators they’re facing in the first few minutes of life. Feral pigs on the mainland ensure they don’t ever get to see the ocean.
It’s breeding time for the flat-back turtles and Crab Island is the largest nesting site in the world for them. They first arrive late afternoon, bobbing their heads out of the water, eyeing up a suitable patch. They then drag their heavy bodies out of the ocean, head up high on the beach and start digging. The front flippers dig a ‘body pit’, before the rear flippers dig an egg chamber, about 0.5m deep. Her flippers are much like hands, having similar control to scoop up a handful of sand and bring it to the surface.
While one flipper reaches deep, the other flicks the previous load away. And so she builds her nest with efficient and coordinated movements, without wasting any time. She deposits about 50 eggs (other species lay at least 100) and covers the nest. The turtle is in a trance-like state when laying her eggs. Once done, she covers her eggs and heads back to the ocean.
The flat-back sea turtle is endangered with extinction. They are unique amongst the world’s 7 sea turtle species: They are known as ‘Australia’s Sea Turtles,’ because they nest only on the nation’s far northern beaches – the most restricted distribution of any turtle. They lay fewer, but larger eggs. They have a skin like shell with upturned edges. And they lack an oceanic phase, staying close to the coast as youngsters, unlike other sea turtle hatch-lings that can travel across large oceans. They are rare and little studied. Currently on the island are sea turtle researchers Mr Brett Leis, Dr Ian Bell and Dr Barry Krueger. Their aim is to collect nesting biology data, describe nesting patterns, and examine 10 of the turtles each night to find out if they are first time breeders by way of laparoscopy.
Inside the turtle, Dr Ian Bell is looking for ovarian scars, the telltale signs left from previously delivered eggs. The future eggs will be laid in another season (they show as white / yellow round dots). Following the examination the cut is stitched shut.
Mr Leis has been researching the Crab Island flat-back turtle rookery for several years and currently manages the Cape York Sea Turtle Project (working for Cape York Sustainable Futures). Both Dr Ian Bell and Dr Barry Krueger are world renowned sea turtle experts. Dr Bell works as a Senior Conservation Officer for Queensland Parks and Wildlife Service specializing in sea turtles, whilst Dr Krueger is a sea turtle biologist who has worked all over the world, more recently on flat-back turtles in the Pilbara region of WA and previously managed the Barbados hawksbill turtle project in the Caribbean for many years.
It is about midnight on Crab Island and life is in full swing, and so is death. While the female flat-backs deposit their eggs, hatchlings emerge by the hundreds, perhaps thousands, all heading to the water. The shell is soft but firm. The hatchlings will be lucky to survive the first few minutes. Laying in wait are the Ghost Crabs that carry them off. If they don’t get them then the Rufus Night Herrons will, or the Beach Stone Curlews, the Jabirus and Pelicans. If any of them should miss some, then large numbers of crocs scoop them up with their heads turned sideways. “Only one in a 1000 will survive into adulthood,” says Mr Leis.
The spotlight reveals the eyes of most crocs, as they feast on the hatchlings on the sand. As soon as the quad bike gets nearer, they run to the water, some more reluctant than others. Whilst driving along the beach, Mr Leis marks the GPS positions of turtles, for later analysis.
Mr Leis estimates that about 500 flat-back turtles came to nest this night. The sex of newborn hatchlings is determined by the temperature of the sand. Cooler sand will produce male offspring. The mainland may be warmer, producing female offspring. Mr Leis, “The mainland nesting population is critical for this fact, however feral pigs are wiping out most nests and this has the potential to cause regional extinction of turtles in the area, including Crab Island, because the population relies on these females.”
The turtle’s length is recorded and she is tagged before being released.
Crab Island is lucky not to have the introduced wild pigs, which devastate the breeding grounds on the mainland.
In 50 years time the newborn will return here, to lay their eggs in the sand, continuing a cycle that started millions of years ago. The researchers have been tracking turtles by satellite, which has shown that flat-back turtles can migrate as far away as 3000km to nest here. “We are in day four now,” says Dr Ian Bell, when asked how many first-time breeders were found. “It seems to fluctuate each day. We had 17 last night, and fifteen were experienced breeders with two new recruits to the population. It’s a very small sample size, but we need to finish off the study to see what the whole 50 look like.”
This night the researchers have found ‘fibropapilloma’ on 2 of the turtles. The disease is a herpes virus afflicting some of the turtles, with ‘cauliflower’ like tumors externally, but can have internal growth as well. The disease was found in Green Turtles as early as 1980s. It now affects all sea turtle species, but has been rarely seen on flat-back turtles. “Fibropapilloma could be a result of stress from pollution or poor water quality,” says Mr Leis.
“Down in Moreton Bay (near Brisbane), a lot of green turtles have fibropapilloma that may be a result of living close to an urban area. Turtles travel far. These flatbacks could have been coming from areas such as Indonesia or New Guinea. It would be interesting to find out where they are picking it up from.”
Some of the flat-backs on Crab Island had part of their flippers and shell bitten off. ”You see a lot of turtles have missing flippers and parts of shell; sharks tend to take a nice clean bite, whilst crocodile bites tend to be a bit more crunched,” explains Mr Leis.
Turtles can cut off their blood supply when losing a flipper. They do have a nervous system and are able to feel pain. “You see some pulling themselves out of the water with only one flipper, so they’re resilient tough girls,” says Mr Leis. “You have to admire their determination and effort to lay their eggs and the foundation for the next generation. I just wish us, as humans, we’re just as determined to ensure that sea turtles do not become extinct. But they face an uphill battle.” Crab Island is the largest nesting rookery for flat-back turtles in the world. Mr Brett Leis has been studying the rookery for 3 years and has been collecting valuable information to aid in the conservation of one of the world’s rarest and least studied species of sea turtle.
The research team has a lot on its plate: Operating from two camps, south of Jardine on the mainland and Crab Island, conducting simultaneous surveys to allow comparative analysis. Rangers in training: The team works closely with the Apudthama Land and Sea Rangers to provide training and to increase understanding in monitoring and research methods. Together with the Apudthama Land Trust and NPARC, they have been working to monitor turtles and protect turtle nests from feral pigs on the mainland beaches, particularly the beaches south of the Jardine River.
An email received with the heading ’World shame coast in Costa Rica’ shows whole communities plundering eggs from nests whilst the turtles are still on the beach. They are carried off by the bags full to be sold. Images cannot be shown for copyright reasons. Mr Leis identified them as olive ridley turtles, “They nest in a phenomenon called ‘Arribada’, in which all the turtles emerge over 1 or 2 nights in the season to nest. Unfortunately, it means they are easily exploited. Ironically, this is the same thing happening in the NPA, however it is feral pigs destroying every nest day after day. This sort of thing is happening all over the world, which saddens me. The once large nesting populations of olive ridleys that occurred in Peninsula Malaysia and Thailand are a classic example of over exploitation of sea turtle stocks. Long term, over-harvest of their eggs saw the population collapse and lead to their eventual decimation. They went from hundreds of thousands of nesting turtles a year to zero… in a matter of decades. Same story, if there are no eggs to hatch, then there are no turtles to come back in the future. This is why both, indiscriminate egg collecting and hunting of adults in the Torres Strait and NPA will have dire consequences: no adult females laying and no hatchlings returning as adults = no more turtles!”
Special thanks for help with this article to Mr Brett Leis.
