The Hatching and Emergence of Loggerhead Turtle (Caretta caretta) Hatchlings

Loggerhead turtle (Caretta caretta) eggs were collected at the time of laying during the summer of 1977 on the beaches of Canaveral National Seashore and the Merritt Island National Wildlife Refuge in Brevard County, Florida. The eggs were placed in land-lines buckets and maintained at ambient temperature in a house trailer hatchery. After 50 to 55 days of incubation whole or partial clutches were transferred to glass observation containers and covered to a depth of 20 cm. Hatching and emergence behavior were visually observed and activity was timed on an event recorder that was activated by four motion switches placed within or above the clutch. Pipping of the eggs occurred at a mean of 60.5 days after egg deposition. Emergence occurred at a mean of 61.8 hours after pipping and 63.1 days after egg deposition. The hatching and emergence sequence was described. It was concluded that hatching and emergence were socially facilitated. A mechanism for socially facilitated hatching was proposed. Volumetric reduction of the nest behavior before or during pipping was described. Emergence may be inhibited by rising temperatures in the morning and stimulated by falling temperatures within a certain range at night. Social facilitation, in addition to the obvious value of providing a means for reaching the surface, was apparently advantageous to hatchlings as they emerged and raced towards the surf en masse. Under these conditions predators are likely to be efficient than they would be if hatchlings emerged singly.