Rhinoclemmys pulcherrima (Gray, 1855) is a semiaquatic emydid turtle which inhabits dry forests from northern Mexico to Costa Rica. Very little is known about its habits, although it is quite abundant in some areas (Pritchard, 1979; Ernst, 1981). This is the first report on its nesting behaviour and is based on three events: a female that nested in 1979, and another that nested in 1980 and 1984. They were kept outdoors in a lOOm2 garden in San José, within the range of the species. Females about to nest become more active than usual and apparently search for a place devoid of grass and roots, under bushy vegetation that perhaps serves as camouflage during the nesting process; nesting may occur anytime from May to December (Castillo, 1986), and includes five basic steps. 1. The female anchors herself to the ground by her forelegs and excavates with alternate movements of the hind legs. The claws help fragment the clods, dirt is thrown backwards. She may stop for short periods, and after about an hour, the hole is about 10cm deep. 2. The tail is oscillated vertically for a few mm. 3. A translucent, thick substance begins dropping from the cloaca, and egg laying begins (Fig. 1a). The head is retracted thrice into the carapace each time an egg is laid (N = 1-3 eggs). The interval between deposition of each egg is 2-3 mm. In all cases the nests were later found open and the eggs had been destroyed, so we could not measure them, but normally they measure about 4.6 x 2.9cm (Castillo, 1986). 4. These are stacked at the bottom with the legs (Fig. lb), and tail oscillation continues for about 10 mm. after oviposition. 5. She covers the eggs with dirt (small amounts initially) which takes some 25 mm. (Fig. ic). The dirt is initially tamped by the claws of the hind limbs, then by the whole terminal part of the hind limb, with a shivering’ movement. The body moves in a semicircle, the forelegs serving as axis, which increases the area covered by the hind legs while tamping. Finally, twigs and other debris are added with hind limbs. When the female leaves the nest, the neck is moved as if hiccoughing. Steps 1-3 in nesting sequence of R. funerea are similar (A. Coto, 1986, pers. corn.), and interestingly, R. punctularia and R. diademata do not dig nests, although their eggs soon become inconspicuous as mud and fallen leaves cover them in the wet forest (Pritchard and Trebbau, 1984). Nest digging is the rule in R. pulcherrima (Castillo, 1986) and might have an adaptive function in the dry environments that it inhabits
