The Olive Ridley Arribada: Nature’s Bounty
Olive Ridleys (Lepidochelys olivacea) are the smallest of all other turtles. They owe their name to the colour of the carapace and skin, which varies from grey to green over different periods of their lives. Our contributors finally realised their long-standing dream of witnessing the life-cycle of these turtles. Their impeccable documentation of the event is a delight to read and a visual treat, this World Turtle Day!
Found in the warm tropical waters of the Pacific, Indian, and Atlantic Oceans, and although found in abundance, Olive Ridleys have witnessed a decline in their numbers over the past few years. The species is categorised as Vulnerable on the International Union for Conservation of Nature(IUCN) Red List. Males and females grow to the same size, however, females have a slightly more rounded carapace as compared to males. The easiest way to identify the gender of an Olive Ridley is by the size of its tail – males have longer tails than females. These turtles spend their entire lives in the ocean and migrate thousands of kilometers between feeding and mating grounds in the course of a year.
In certain quaint seaside villages of Orissa, turtles throng the coasts each year in huge numbers. This occurs majorly at three locations, namely, islands of Gahirmatha, Rushikulya, and the mouth of Devi River.
The mere presence of the turtles along the Indian Ocean suggests that there is a conducive environment being offered and suitable habitat for these wonderful creatures. These turtles migrate several hundred km in the sea waters to finally congregate at nesting sites, which is a unique feature with the Ridlyes, both Olives and Kemp’s Ridley. This phenomenon of nesting is called “Arribada”.
Life Cycle: Olive Ridley (Lepidochelys Olivacea)
Olive Ridleys, along with their cousin, the Kemp’s Ridley turtle, are best known for their unique mass nesting called “Arribada”, where thousands of females come together to lay eggs. Females return to the very same beach from where they first hatched, to lay their eggs. During this phenomenon of nesting, up to 6000,000 and more females emerge from the waters to lay eggs. Olive Ridley sea turtles are endemic to the Odisha coast, and official figures indicate that 90% of the population of sea turtles along the Indian coastline comes to the Odisha coast for nesting. The other nesting sites in the Bay of Bengal are Andhra Pradesh, Tamil Naidu, etc, but are occasional and smaller in number. In the Indian Ocean, they are seen on the Coromandel coast, Velsa (Konkan belt), and Sri Lanka.
As the mating occurs in the sea, the males retreat to the foraging ground post-mating. The females linger around looking for shallow waters for over a month(the general figure is 45 days) till they reach the beaches to lay their eggs. As per forest officials, nesting seasons in India last from around Jan-Mar depending upon conducive and favourable conditions prevailing at that point in time. The females lay around 100- 150 eggs per individual. Each female takes around 30 minutes to an hour to dig a hole around 2-3 feet with her flippers and lay her eggs.
Eggs Laying (Arribada)
The female turtles lay eggs and cover their nests with plastron in approximately 45 minutes (we monitored this). Upon interacting with forest officials, we came to know that compared to previous years where there have been instances of no nesting at all due to various reasons like change in temperature, cyclonic disturbances, salinity, oil spillage, etc, this year had been heartening. We could also spot one tagged turtle, and forest officials were ecstatic as she revisited the same place to lay eggs.
We saw huge congregations of turtles – there was hardly any space to walk even with measured and careful footsteps. The most important and noticeable aspect was the hard work of forest department staff. Even NGOs were actively involved and were working day in and day out during the season of nesting till hatchlings move safely into the sea. The local villagers have been instrumental in discouraging poaching and trade of products like eggs, meat, carapace, etc to a huge extent. The young children also participate in saving the turtle babies from being predated by numerous predators like crows, dogs, jackals, hyenas, wild boars, and raptors.
The next step was to wait for 45 days to be able to watch in awe the first few unsure steps being taken by the tiny Olive Ridley hatchlings. After about 45-50 days of laying eggs, the hatchings begin to pip, or break out of their eggs, using a small temporary tooth located on their snout, called a caruncle.
We reached the site a day before, i.e Rusikulya beach, Odisha. With a motley group of environmentalists and tourists, we cheered as the hatchings poured out of the sandy pits, and took their first wobbly steps. We watched hundreds of newly hatched Olive Ridley turtles walking over the carpet of sea sand, wadding towards the white and blue waters of the Arabian Sea.
Whether hatchlings are male or female depends on the temperature when they are in the nest, known as the Pivotal temperature. While warmer temperatures yield more female offsprings, more males are born if temperatures are cooler.
The First Steps
The last walk of a hatchling from the nest to the sea is very critical to the imprinting of a geomagnetic field that helps the female olive reach their place of birth as adults. The struggle of the newborn is quite apparent as it takes in its bearings and tenses each and every sinew in its tiny body amidst a whirlwind slapping of minuscule flippers. Around it, hundreds of similar-looking turtle babies, some as small as my thumb wobble, thrashing their flippers on the wet sand, moving ahead with small jumps losing direction and bumping into each other, their tiny bodies etching crisscrossing trails in the sand. While large stretches of India’s coastline are home to the turtle species, the Rusikulya beach is said to be the most popular nesting site on the Orissa coastline.
The journey of the newborns towards the sea is extremely challenging. It is so perilous that only a few hundred make it to their destination out of the thousands of eggs laid. Wild predators and overpopulation on the beach are major threats, but this is where the role of conservation societies and NGOs comes in, along with forest officials and the local population.
Nesting Sites’ Challenges:
- Industrial areas near the vicinity of Rushikulya.
- Artificial lighting along the coast at the nesting sites
- Use fishing mechanisms that are not turtle-friendly for deep-sea fishing.
- Changing pattern of the beach and shoreline due to tidal dynamics and cyclonic disturbance over a period of time.
- Beach salinity, pollution levels due to oil spillage, temperature.
- Hatchlings being consumed by a wide range of predators from scavengers to birds, mammals, and even crabs.
- Shrinking habitat due to beaches divided into fragments and beach erosion leading to a shortage of available suitable space for nesting.
Images Credits (for all images): Shakti and Amar Bishnoi