Unstable social structure indicates low diversity of relationships in the spotted forest skink Sphenomorphus maculatus

Abstract

To the date, we hardly understand what and how affects the social structure in animals. Longevity and social stability must be the key factors influencing the relations among individuals. To test this suggestion, I described the spatial and social structures of the spotted forest skinks (Sphenomorphus maculatus) from southern Vietnam in the breeding seasons of 2008 and 2009. This species is known to have short lifespan and low social stability among seasons. No difference between male and female space use was revealed. Home ranges were 107.7 ± 23.68 m2 in males and 78.9 ± 27.27 m2 in females, and these contained core areas and activity centres within them. Home ranges and their parts overlapped among individuals of all sexes and were used by several residents, although not at the same time. Intrasexual and intersexual relationships were agonistic, more aggressive among males, and characterized by hierarchy with males as dominants and females as subordinates. Dominance status in males was supported by aggression in males and by submission in females. Females avoided sexual encounters, and no affiliation between sexes or mate guarding behaviour were revealed. A poor social behavioural repertoire was limited by aggressive and submissive behaviour, and it was difficult to distinguish sexual courtship from agonistic interactions. Hence, social and spatial structures were relatively simple in comparison with other saurian species and low stability of social composition is the most probable reason of such a social simplicity.