Multiple captures of fulvous harvest mice (Reithrodontomys fulvescens) and northern pygmy mice (Baiomys taylori): evidence for short-term co-traveling

Abstract

Multiple captures of small mammals (finding >1 animal in a single trap) are often used to infer pair-bonding activity in arvicoline and cricetine rodents. We analyzed data from a 2-year trapping study to determine whether fulvous harvest mice ( Reithrodontomys fulvescens J.A. Allen, 1894) and (or) northern pygmy mice (Baiomys taylori (Thomas, 1887)) travel in mixed-sex mated pairs. A significant majority of multiple capture events (MCEs) in R. fulvescens were mixed-sex, whereas sex composition of pairs in B. taylori did not differ from random. Multiple capture probability was significantly positively related to abundance and unrelated to sex ratio in both species. Multiple captures of B. taylori were more common in winter, suggesting that individuals may associate to huddle for warmth. Masses of singly captured and multiply captured individuals were not significantly different in either species, contraindicating trap bias. Only one co-captured mixed-sex pair was recaptured as a pair (in R. fulvescens) and several animals of both sexes in both species were co-captured with multiple individuals. We concluded that R. fulvescens co-travels with mates for variable lengths of time, but we found no evidence that multiple captures of B. taylori are related to reproductive behavior.