TURTLE MONITORING IN THE iSimangaliso WETLAND PARK
During turtle season (Nov-Feb) we arrange one turtle drive every night at low tide. Due to the concession legislation we have access to the beach at the low tide mark for 4 hours. We are permitted to drive the length of the beach looking for the females and the hatchlings. There is a charge for the turtle drives but no charge for turtle walks.
Night drives are tide-dependent and may happen just after dinner or in the early hours of the morning and can sometimes be as long as three hours
Both loggerhead and leatherback turtles nest during the summer months at night (November – February). Steep beach faces make it easy for loggerheads to swim through the surf over low lying rock ledges. The females emerge from the surf and rest in the wash zone on the beach. Here they assess the beach for any danger by lifting their heads and scanning the beach. Satisfied that there is no danger they then proceed up the beach to well above the high water mark.
Having found a suitable site, the female commences by excavating a body pit, this enables her to lie with the top of her carapace level with the beach. She then digs an egg cavity with her hind flippers. The egg pit is a flask shaped hole about 50-80 centimetres deep. A normal clutch constitutes 100-120 soft white shelled eggs which are deposited into this hole. When all of the eggs have been laid the female fills the hole with sand and kneads the surface until the sand is packed hard. Once this is done, she disguises the nest site by throwing sand with her fore flippers over the nesting area. Leatherbacks can return up to seven times to lay eggs, while loggerheads return up to four times in a single season.
Loggerhead turtle eggs take between 55-65 days to mature and leatherback turtle eggs take between 65-70 days. Once ready to emerge the hatchlings cut their way out of the egg with a special egg tooth on the end of their beaks. After the bulk of the eggs have hatched the hatchlings start digging at the sides of the nest. The hatchlings will often wait during the heat of the day, until the sand has cooled before emerging and heading to the sea.
The most serious threats that are present at various life stages
- Nesting – Egg collecting, slaughtering for meat, coastal development, sand mining and beach driving
- Home Ranges – (coral reefs, sea grass beds, open oceans) These are disturbed or destroyed by bad fishery practices, pollution and global warming.
- Migration Movements – Their migration routes are threatened by trawlers or drift nets and long lines.
- Littering in the Sea – The leatherbacks feed mostly on jellyfish – with the serious problem of plastic bags littering our seas, the bags are often ingested by turtles who choke on this toxic waste.
Loggerhead and Leatherback Turtle Monitoring
Seven species of marine turtles exist in the world’s oceans today, therefore turtles are important indicators of ocean health. There are five species found off the Kwa-Zulu Natal Coast, namely, the loggerhead, leatherback, hawksbill, green and olive ridley turtles. Of these five species that occur in South African waters, only the loggerhead and leatherback females nest along our shores.
Monitoring Turtles for 40 years
From the early 1960’s, concerted efforts were made to enforce legislation banning egg collection and the harvesting of adults. In 1963, under the auspices of the Natal Parks Board, a Turtle Conservation and Monitoring programme was initiated along the north- eastern coast of Kwa- Zulu natal which is now the iSimangaliso Wetland Park.
The purpose of the project
To monitor and record nesting populations of loggerhead and leatherback sea turtles along the eastern seaboard and simultaneously provide protection of the females during this vulnerable stage on the shore.
The 56 kilometer of beach, north and south of Bhanga Nek, in the iSimangaliso Wetland Park, is the main focus area of the project.
After the incubation period the nest breaks open and the hatchlings emerge – the sex of the hatchlings, like crocodiles, is determined by the temperature within the nest but with opposite results. Females occur between 32-34 ºC and males occur in cooler temperatures. The success rate of the hatchlings is very low. One of the biggest threats is the honey badger that patrol the dunes for nests. The nest often opens at night to minimize predation by crabs and birds. Once in the sea the hatchlings are at risk from fish and squid and because of all these factors it is estimated that maybe two of each annual nesting survive to become an adult.