We analyzed dual-capture data collected during longitudinal studies monitor
ing transmission and persistence of Sin Nombre virus in rodents in Colorado
. Our data indicate that multiple captures (two or more rodents captured in
a single trap) may not be random, as indicated in previous studies, but ra
ther the result of underlying, species-specific social behavior or cohesive
ness. In the pairs we captured, most often, rodents were of the same specie
s, were male, and could be recaptured as pairs. Therefore, dual captures of
rodents, which are unusual but not rare, tend to occur among certain speci
es, and appear to be nonrandom, group-foraging encounters. These demographi
c and ecologic characteristics may have implications for the study of the t
ransmission of hantaviruses.