Unique second Arribada at Gahirmatha

Abstract

Gahirmatha (20° 42' N, 87° 5' E) in Orissa, India, is one of the largest rookeries for olive ridley sea turtles (Lepidochelys olivacea) in the world. The turtles usually arrive around November for mating. The first mass nesting occurs in January and the second mass nesting occurs about 60 days after the first. In general, the number of turtles nesting during March is less than that of the January mass nesting. But this year in March, the turtles nested in record-breaking numbers, not only more than that of the first mass nesting of 1987, but also the largest number since 1976. The nesting took place from 8 to 14 March 1987. A daily account of the nesting is presented in Table 1. The total number of turtles emerging during the first mass nesting in 1987 was 245,157, restricted to a stretch of four km, from 5 to 14 January. The second mass nesting covered a six km stretch of beach. One of the peculiar features was that the emergence started at 1:30 PM on March 8 in bright sunlight. This is contrary to the usual behavior of the turtles, which usually emerge to nest either after sunset or during the day with an overcast sky. The mass nesting continued until the next morning. On 9 March, the emergence started in the evening, reaching a peak at 9:30 PM, when the beach became totally covered with turtles. The mass nesting occurred in the same area where the turtles had laid eggs during the first mass nesting. The hatchlings resulting from the first mass nesting were ready to emerge when the second took place. The result was that the hatchlings as well as some of the developing eggs were dug out of the sand by nesting turtles. A considerable number of hatchlings were either thrown into the air or buried in the sand due to the nesting activity of the turtles. Thus, a large number of hatchlings died due to the second mass nesting. The number of turtles nesting reached a maximum on the third day. In the frenzy to find a nesting place, the turtles migrated further and further away from the water line and even climbed the sand dunes. What was interesting was that the turtles cut into the wire fence of the 30'X20' hatchery set up by the Wildlife Division by cutting it with their beaks. Some of them even nested there, digging out the transplanted nests. The concentration of turtles was such that 3 to 5 turtles were found digging in the same place with their backs towards the same spot. This was a comical sight, as the simultaneous digging resulted in filling of one's body pit by another. The result was that none could dig a proper nest for laying. Due to the destruction of nests resulting from the high concentration of activities, the beach became littered with broken shells and dead hatchlings.