Spatiotemporal variation in Akodon montensis (Cricetidae: Sigmodontinae) and hantaviral seroprevalence in a subtropical forest ecosystem

Relatively little information is available concerning the natural history or population ecology of the montane akodont, Akodon montensis, a sigmodontine species that harbors Jaborá and Ape Aime hantaviruses. On the basis of mark-recapture sampling of 3 locales during 2 years, this report provides comparative data on populational and other characteristics of the species near its distributional limit, in the Upper Paraná Atlantic Forest in Paraguay. We found A. montensis to be almost exclusively terrestrial (nonarboreal) and to vary in population density among locales and between years, findings consistent with earlier studies. Population density was not related either to neotropical seasonality or to most precipitation variables, but sex ratio varied seasonally, which has not been reported previously. We evaluated the seroprevalence of hantavirus in A. montensis, in association with external, populational, and individual variables. As in most previous studies of rodent–hantavirus systems, seroprevalence varied among sampling locales and was higher among males. However, unlike previous reports, especially those from North America, we did not find a correspondence between seroprevalence and population density, seasonal variation, or most precipitation variables. Simple and direct associations between seroprevalence levels and either seasonality or precipitation may be less characteristic of humid neotropical or subtropical systems. Our analyses revealed that seropositive animals exhibit several noteworthy behavioral and life-history modifications, in particular that they have larger home ranges than do seronegatives; exhibit greater maximum distance moved; have greater home range displacement between sampling sessions, particularly those individuals that are seroconverting during the same period; and have greater longevity, especially among males. In general, these characteristics could be postulated as favorable to the capacity of the virus to be transmitted horizontally to other hosts.