Population dynamics of Dromiciops gliroides (Microbiotheriidae) in an austral temperate forest

Abstract

Dromiciops gliroides is an arboreal marsupial endemic to the southern temperate forest located between 36°S and 43°S in both Chile and Argentina. This species is a key seed disperser of many native plants, including the keystone mistletoe, Tristerix corymbosus. We studied the population fluctuation of D. gliroides and the possible effects of natural disturbances on the population. We estimated density, abundance, survival, and recruitment ratios for 7 years (2009-2011 and 2013-2016) at Reserva Llao Llao, Argentina, using capture-recapture techniques. A Jolly-Seber model with robust design was fitted using a hierarchical Bayesian approach. The estimated mean abundance during these 7 years was 81 individuals. The highest abundances were observed in 2009, 2010, 2011, and 2014 (98 individuals on average). The years with lowest abundance were 2013, 2015, and 2016 (60 individuals on average), which coincided with the occurrence of natural disturbances in the study area (eruption of the Puyehue-Cordón Caulle volcano, the flowering of Chusquea bamboo and a subsequent rodent outbreak, and an unusually dry summer). These results suggest that the observed population fluctuations of D. gliroides could be related to natural forest disturbances.