Trajectory assessment of the vulnerable marsupial Dromiciops gliroides in the Patagonian temperate forest

Abstract

We studied the movement of the marsupial Dromiciops gliroides by means of an innovative approach that makes use of two complementary techniques, specifically devised for the monitoring of small animals that live in dense forests. Despite playing a key role in the Southern Temperate Forest of Patagonia, very little is known about the ecology and habitat use of this ?almost threatened species? (according to IUCN), the only living representative of an entire order (Microbiotheria). We present here novel results about the movement and explored area of D. gliroides at different spatio-temporal scales using complementary approaches: the spool-and-line and a radiotelemetry techniques. Both are complemented in such a way that, while the first one allows to obtain trajectories at small spatial scale with very precise resolution for relatively short periods, the second one provides longer temporal records at larger spatial scales adding temporal resolution. We show in this work very precise nocturnal trajectories unknown so far of 41 individuals of D. gliroides using spool and line, analyzing several of their statistical properties. For instance, from the turning angle distribution we find that, after release, the animals followed paths that exhibited little angular deviation between steps. In a complementary way, using radiotelemetry, we were able to study the velocity distribution of their movements, assessing a most probable value of 2.0 ± 0.8 m/min and a median value of 7.2 ± 2.8 m/min. The combination of both approaches brings new opportunities for studying other cryptic and poorly known forest dwellers.