AGGRESSIVE BEHAVIORS AND THEIR EFFECT ON RESOURCE USE BY FEMALE SINCELLA LATERALIS

Abstract

INTRODUCTION The study of lizard behavior has benefitted greatly from observation and analysis of the behavior of North American species. In particular, studies of North American species within the Iguania clade (sensu Sites et al. 2011) form the foundation of herpetology’s understanding of communication and territoriality in lizards (reviewed in Carpenter and Ferguson 1977; Stamps 1977). In general, North American iguanians communicate with each other via visual displays including “head bobs” or “push-ups” in which the lizard raises then lowers its head and/or front end of its body in a stereotypical pattern (Carpenter 1978). Such visual displays are employed for communication related to territorial defense or reproduction in many lizard species, including members of the North American genera Sceloporus (Sheldahl and Martins 2000; Haenel et al. 2003), Crotaphytus (Baird et al. 2001; Baird 2013; York and Baird 2017), and Uta (Fox et al. 1981). Results of such studies have made it possible to probe the relationship between phylogeny and territoriality in lizards (Stamps 1977; Martins 1994; Vitt and Caldwell 2014). ABSTRACT: Studies of aggression and space use are essential to understanding resource use by reptiles, particularly lizards. Research in this area, however, exhibits bias in that the seminal work has been done on (1) species that are highly visible in their habitats (e.g. Iguanians); and (2) males. Studies of secretive species such as skinks and of females are less common. Here, we present results of a lab study of dyadic encounters of adult females of a common North American skink: Scincella lateralis (Little Brown Skink), and compare them to results obtained from an earlier study of adult males of the same species. Female S. lateralis never interacted unless they were within one body length of each other. The most common behavior exhibited was avoidance of one lizard (the subordinate) away from the other lizard (the dominant). As a result, the two lizards spent more time apart than close together and rarely shared the retreat. The larger of the two females was dominant in 9 of 10 trials. Compared to adult males, adult females showed far fewer aggressive behaviors such as lunging or chasing, and never bit each other. Unlike males, however, subordinate female S. lateralis exhibited tail twitching significantly more often than did dominants, suggesting this behavior may be a social signal for females, though the data suggest there may be other possible functions. Despite differences in the frequency of behaviors exhibited, patterns of space use and retreat use were the same in females as they were in males.