Behavioral repertoire of the Brazilian spiny-rats, Trinomys setosus and Clyomys laticeps: different levels of sociality

Abstract

Behavior is a useful trait for comparative studies that provide the comprehension of phylogenetic relationships among species. Here, we present a description of two spiny-rats species’ behavioral repertoire, Clyomys laticeps and Trinomys setosus (Rodentia: Echimyidae). The affiliative and agonistic behavioral patterns were sampled during a three-year study of captive populations of wild animals. Observational data were collected in two phases under different arrangements of individuals in groups. We also compare the behavioral traits of T. setosus and C. laticeps with the known behavioral patterns of Trinomys yonenagae. We add categories to the previous descriptions of T. setosus and a standard ethogram for C. laticeps. Trinomys setosus showed a visual and vocal display we called foot-trembling, which was not described in this form and function for other species studied until now. We discuss the differences in their sociality levels and similarities and differences among behavior patterns and repertoires.

Movement patterns of the rodent Trinomys dimidiatus in Atlantic Forest

“…Here, the different effects of body mass for each sex could be explained by a polygynous mating system, which is frequently observed in echimyids (Adler, 2011, but see McEachern et al, 2009, so males, especially large ones, move larger distances because of their energy reserve but also to find more partners. Another interpretation could be that part of the accumulated energy in heavier females is allocated to reproduction efforts, such as defending newborns from aggression or defending areas with greater resource availability, as observed for other rodents (Cantano et al, 2023;Godsall et al, 2013;Ostfeld, 1986;Wolff, 1993).…”

“…Therefore, given that tropical rodents may reproduce throughout the year (Bergallo & Magnusson, 1999), females of T. dimidiatus may keep movements close to the nest regardless of rainfall amount and food item availability to avoid males' aggressions towards newborns. Although aggressions to newborns have already been observed in T. setosus (Cantano et al, 2023), group formation, burrow sharing and social behaviours have been also recorded for both T. setosus and T. yonenagae (Cantano et al, 2023;Santos & Lacey, 2010). Thus, the occurrence of infanticide and its effects on T. dimidiatus females' movements must be further investigated.…”

“…Byrne et al., 2014; Saitoh, 1995; Schneider et al., 2003; Slip & Shine, 1988; Spirito et al., 2020; Wells et al., 2008) and are often considered as temporarily or definitive dispersive movements. Also, agonistic behaviours towards males are more frequent in Trinomys setosus and may indicate a male‐biased dispersal in the genus Trinomys (Cantano et al., 2023). All individuals that changed core area location did it only once and most changes occurred during the initial captures and then the individuals kept being captured in the new core area.…”