Abstract

SHEPHERD, John D  and  DITGEN, Rebecca S. Small mammals and microhabitats in Araucaria forests of Neuquén, Argentina . Mastozool. neotrop. [online]. 2016, vol.23, n.2, pp.467-482. ISSN 0327-9383.

We used mark-recapture techniques to sample small mammals in two Araucaria araucana-Nothofagus forest plots at dry and mesic ends of a moisture gradient in Neuquén, Argentina. In summer and fall trapping sessions from 2004 to 2007, we had 678 captures (323 individuals) of 6 species in a total of 5300 trap nights. Abrothrix hirta (64% of captures) was captured in every trapping session, but Oligoryzomys longicaudatus (26%) was trapped only in the fall. Both species had lower body weights when Araucaria seed crop was very small. O. longicaudatus appears to migrate into Araucaria forest from other habitats to exploit the autumn seed fall. We measured 9 canopy and 19 understory variables around 100 trap sites and used factor analysis to identify 4 canopy and 6 understory factors in each forest. We used regression to model capture-vegetation relation­ships. Features of the understory had greater influence than did the canopy. Capture-vegetation models were more complex in the moist forest than in the dry forest. In the moist forest, more A. hirta and O. longicaudatus were caught in patches of bamboo (Chusquea culeou), and away from grass and open areas, but these species differed in capture rates in other kinds of understory vegetation. There was less overlap between species’ mi­crohabitats in the dry forest. More individuals of both species were caught away from patches of fallen logs, but A. hirta and O. longicaudatus, responded differently to other features of the understory. Spatial, temporal and behavioral differences in the way A. hirta and O. longicaudatus use these forests and its Araucaria seed falls promote coexistence and community complexity.

Keywords : Abrothrix hirta; Araucaria araucana; Oligoryzomys longicaudatus.