NATURAL HISTORY OF LEIOCEPHALUS SEMILINEATUS IN ASSOCIATION WITH SYMPATRIC LEIOCEPHALUS SCHREIBERSII AND AMEIVA LINEOLATA

Abstract

We examined diet, habitat use, and behavior (focal animal observations of intraspecific interactions, escape behavior, and activity period) of Leiocephalus semilineatus from near Puerto Alejandro, Provincia de Barahona, República Dominicana, and compared some parameters to similar data collected at a site near Baní, Provincia de Peravia. Leiocephalus semilineatus is found in sympatry in dry scrub forests at both sites with Ameiva lineolata, an active-foraging teiid of approximately the same size, and at the Puerto Alejandro site with a larger congener, L. schreibersii. Leiocephalus semilineatus and L. schreibersii from Puerto Alejandro exhibited sexual size dimorphism, whereas L. semilineatus from the Baní site and A. lineolata did not. Leiocephalus semilineatus spent most of the time motionless; other observed activities were interactions with conspecifics, movement, and feeding. Lizards were active from shortly after sunrise to sundown, although activity peaked in late morning. Mean cloacal temperatures of L. semilineatus did not differ significantly from those of the other two species, but were significantly above ambient temperatures. Reproductive condition of collected specimens was examined and no correlation was found between snout-vent length and egg, follicle, or testis size. Clutch size was 1–2. Diets consisted primarily of invertebrates and did not differ significantly between the three species. Members of the iguanian lizard genus Leiocephalus are ground-dwelling, sit-and-wait foragers endemic to the West Indies (Pregill, 1992). Ten of the 23 currently recognized species are found on Hispañiola (Powell et al., 1996). Leiocephalus semilineatus (Figure 1), a Hispañiolan endemic, inhabits dry lowland habitats in the Culde-Sac Plain in Haiti and the Valle de Neiba and the Llanos de Azua in the República Dominicana, but may be absent from the eastern Valle de Neiba. This species has been found in dry and spiny scrub forest, open rocky terrain, along arroyos, and around garbage dumps. It is found primarily on the ground, usually perched on rocks, but sometimes in vegetation including dead agaves and small shrubs. Several members of the genus Leiocephalus have been subjects of natural history studies, including Leiocephalus carinatus (Schoener et al., 1982), L. psammodromus (Smith, 1992, 1994, 1995; Smith and Iverson, 1993), L. schreibersii (Schreiber et al., 1993), and L. barahonensis (Micco et al., 1997), but little is known about the basic biology of L. semilineatus. Schwartz and Henderson (1991) described L. semilineatus as a xerophile associated with gravelly or rocky areas. In at least some parts of its range, Leiocephalus semilineatus is found in sympatry with the teiid Ameiva lineolata, an active forager of approximately the same body size, and with its larger congener, L. schreibersii. Because these areas of sympatry are ideal for studying niche partitioning, we examined aspects of the natural history of L. semilineatus and compared them to those of sympatric L. schreibersii and A. lineolata in order to evaluate the extent to which size of individual and foraging mode affect potentially competitive interactions.