Night of the turtle invasion

Turtles Costa Rica

[words © Mark Eveleigh]

The sun rose on a battlefield that was thick with flying dust. Hunched shapes lay in tortured postures, writhing on the sand. Others crawled, inch by painful inch, towards the relative cover of the waves…where sharks and crocodiles waited for them. In their exhaustion they could only make 10 steps before, danger or no danger, they were forced to stop and lie still, gasping. Around them hundreds of vultures flapped and bickered. Thunder rolled in from the watery horizon and, in the gloomy mangroves, coyotes could be heard whining at the lightning that drove them off the beach.

Beyond those twisted, briny trees, the tropical forest of Guanacaste cloaked the hills in a blanket that stretched inland almost to the chain of volcanoes that form Costa Rica’s spine. We had trekked through much of that forest during the previous week – under the accusing bellows of territorial howler monkeys – and had arrived on remote Nancite Beach during a brief, golden sunset the evening before.

As soon as we had stepped out onto the sand we sensed the mood of anticipation that seemed to fill the whole bay. A few frock-coated vultures, hopping along like busy undertakers, were there to meet us. Though we could see nothing among the gilded waves, we were aware that something was amassing – converging on this short stretch of Central American coastline.

This particular beach is the only one in the world where massive numbers of endangered Pacific Olive Ridley turtles swarm in the phenomenon that is known in Spanish as the arribada (literally ‘the coming up’). Nobody knows how they are able to coordinate so that they all lay their eggs over a period of a few days, or why they pick this particular kilometre-long stretch of sand in preference to other, apparently identical, patches of coastal real estate next door.

Costa Rica is home to six of the world’s eight species of marine turtles and, despite being only about the size of Wales, the aptly named “Rich Coast” harbours an incredible six percent of all the world’s biodiversity. In ecological geek-speak, Costa Rica has been described as “a mother-lode of eco-diversity, emanating bio waves north and south”, but for the amateur wildlife enthusiast it is simply one of the world’s last “paradises”.

This section of the Pan-American land-bridge is home to an unusually cosmopolitan community: South American jaguars share territories with North American pumas; coatimundis hunt alongside coyotes; collared peccaries browse with white-tailed deer; kinkajous and possums; monkeys and squirrels; ocelots and foxes; macaws and magpie jays; quetzals and cuckoos…

There are 830 species of birds, 400 reptiles, 10,000 plant species…and the National Biodiversity Institute has been counting insects for decades! For a splash of colour the country has been blessed with 1,200 orchids, 57 hummingbirds and no less than 1,400 butterflies, including the magnificent Blue Morpho, which the indigenous tribes believed to be fallen bits of heaven.

Less than a century ago the country was still almost covered in impenetrable rainforest. The miracle is that Costa Rica realised the importance of its unique riches while there was still time and – more surprising still for such a small and not at all affluent country – resisted the temptation to exploit them wholesale in search of the quick buck.

Today there are 161 protected areas. But, more importantly, the people live cheek-by-jowl with their wildlife in a way that you are unlikely to find elsewhere; you can often see more animals during a single walk through a Costa Rican village than you will see in the greatest national parks of many other countries.

That is not to say that there are not still problems: deforestation, a result of the burgeoning population, is threatening sensitive eco-climates; degradation is rife in over-exploited reserves near the capital; illegal fishing and poaching continues.

While the Olive Ridley turtles at Nancite Beach have to deal with their natural predators they are, at least here, protected from the most voracious of egg thieves: the human poachers who sell the eggs as pick-me-up tonics in the bars of the capital. Nancite, though part of Santa Rosa National Park, is off-limits to poachers and tourists alike and to earn our entry permits we had to agree to help with whatever work was needed at the research station. So on arrival we reported to the collection of beachside shacks that Lenin, the Costa Rican vigilante guard, was privileged to call his “office”.

Although even Lenin could not yet have known it, we had arrived by pure chance on the night of one of the biggest arribadas of the year.

By 9pm the first turtles were already emerging. In the moonlight we could see shiny black domes rising up on the water’s edge and now and then a head would bob up out of the waves where the males had already congregated. We were careful to keep our distance as the first “scouts” peered around short-sightedly, trying to make up their minds whether the coast was clear. The long, hard slog up the beach, on fins that are perfectly designed to propel them for hundreds of watery miles, was almost painful to watch and they left trails that looked strangely like the tracks of amphibious landing-craft. These first arrivals were mostly tired old maids, struggling up the sand to offer their eggs – and if necessary their bodies – to the waiting predators for the benefit of the younger, prime layers who would come later with the main “invasion”. Perhaps they understood that the mangroves were a source of danger and that they would make an easy meal for a jaguar or crocodile but they would not be swayed from their mission and, once they started digging, seemed to be totally oblivious to our presence.

The oldest of these veterans would have been over 50 and weigh about 45kg. Their faces were strangely human with their mournful, down-turned mouths and tearful eyes that wept as a reaction to the unaccustomed dryness. The youngest may have been cruising the Pacific for 15 years, never having been on dry land until they were irresistibly drawn by the scented waters that flow off this beach.

Lenin assigned us each a section to survey. “A turtle takes an average of an hour to come out of the water, lay her eggs and get back to the sea,” he explained. “So we only have to do a count every hour to know how many turtles have visited.”

These figures provide the only accurate estimate of the world’s Olive Ridley population. They are not reassuring. In 1999 60,000 turtles visited Nancite, but by 2001 the figure had dropped to 17,000. Very little is known even now about the arribada phenomenon but naturalists believe that fluctuations may always have been the norm and that large numbers of turtles will periodically abandon a beach, to let it lay fallow so that they will not contaminate their own collective nest with rotting eggs. Where they go to when they abandon Nancite is another part of the mystery however.

By 11pm there was a constant two-way traffic of turtles heading stoically to and from the sea. It seemed that each had a fixed idea of exactly how far up the beach she wanted to be. Some settled for the high-tide line and others continued almost into the trees before they began to dig a pit with their hind fins. There were a few battle-scarred old matrons who barely got to the edge of the water before they started to dig, obviously thinking, “that’s it, I’ve done my bit.” Each turtle would then lay a batch of around 50 eggs, before filling in the nest and tamping it hard by pounding her weight from side to side.

In the early hours of the morning the main landing came. It was a veritable invasion of protein, designed to overwhelm the hunger of all the predators – jaguars, pumas, crocs, coyotes, coatimundis, racoons, vultures and even the hermit crabs that would gorge themselves on overturned nests. Arriving in sufficiently intimidating numbers, the turtles have been known in fact to drive other predators off the beach. As we patrolled we did our best to disperse the vultures that were now confident enough to snatch the eggs away even as they emerged from the labouring mothers. Lenin showed us a turtle carcass and the tracks of a large crocodile at the end of the beach. Though we worked by moonlight we would occasionally shine our torch-beams to illuminate the eyes of coyotes and racoons, digging frantically after fresh eggs.

A final corps of veterans came later, to lay their eggs as a protective layer on top of this immense clutch. By the time the stragglers had arrived in the hazy dawn we had walked miles between the gasping creatures, and had counted 2,464 turtles. It was sad – almost tearful even – to witness the risks and the strain that these animals underwent. Hundreds of times I watched that gruelling climb up the beach into the alien, dangerous land, the exhausting digging, laying, burying and pounding, and then the even more tiring struggle back to run the gauntlet of marine predators.

From the haunting memories of that incredible night some images stand out: the constant thump of pounding belly-plates, like minor earthquakes resonating through the sand; unfertilised juvenile turtles that sat patiently on their nests, and then filled it back in… without laying anything; the stubborn old female who butted her head against my back because she had decided that wanted to lay her eggs exactly on the patch of sand that I had chosen for a well-earned rest!

But among the thousands of amphibians that had joined this incredible migration – and even among the carnage of dawn when the vultures, corpses and pillaged nests became fully visible – there was one particular turtle that seemed to epitomise this desperately fatalistic drive of survival that has gone on for 100 million years. Sometime in her earlier years she had been mauled by a shark and had lost the back of her shell and most of her right fin. Somehow she had survived and now, smaller than her companions, she was something of a runt. She was one of nature’s ‘fall-girls’ – living only to take the brunt of whatever misfortune might befall her species – and with her exposed, wrinkled backside she would have been a prime target for the coyote that slunk away as we arrived. We stayed close to guard her and to keep away the vultures that were waiting to snatch the eggs away.

To add to the calamity, she had chosen to lay right on top of another nest and while her crippled fin uselessly went through the digging motions, her good one was making a sandy omelette out of healthy eggs. We pulled unbroken eggs away from her mangled back end and by the time she started laying we had a little heap of seven leathery lottery balls to slip back into the hole.

With single-minded determination she carried out her task and, still ignoring us completely, turned back for the long crawl to the sea. My heart was in my mouth as I watched the water take her weight and she slipped through the waves towards the ocean.

It occurred to me that a lottery was exactly what this was. The fate of this crippled old lady was unimportant in comparison with the survival of the species, which had been bid for in a big way during this single rainy-season night. This weakened individual was worth less as a breeding animal than the others around her; it would be nature’s way if she should be sacrificed to save another, more able, breeder.

When the odds are thousand-to-one against a turtle surviving to breed, the seven eggs that we “replanted” would mean nothing. But in being blessed with this humbling experience we felt that we had won a sort of lottery ourselves and it felt good to do whatever we could to stack the odds even a little bit more in favour of these wonderful creatures.

This story was first published in Wanderlust; the image above is the double-page spread opener from that feature. Mark has a feature on one of our favourite spots, West Bali, in the current issue of Wanderlust.


  • hithazn says:

    Heyy.. Damn cool article…..But, i’d like to add something to it: The Olive Ridley turtles arrive at the east coast of the Indian Peninsula every year between Dec-April as well…. And I had a chance to do the turtle walk- a volunteering program to re-locate the turtle eggs to another safe location for their hatching…. 🙂 We collected about 200 eggs in one 1 night 🙂

  • Mark Eveleugh says:

    Very happy that you liked the article. Really interesting to hear that the Olive Ridleys land in Eastern India too. Life has got to be incredibly tough for these animals – just imagine that you would have to run your collection for 5 nights to have a fighting chance for one of those babies to survive! That’s just with natural predation: I worked on assignment with a turtle study in Spain once and researchers estimated that 30,000 marine turtles are caught accidentally by fishermen each year in Straits of Gibraltar.
    – ME

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