Spatial ecology of the water opossum Chironectes minimus in Atlantic Forest streams

Abstract

Spatial ecology of the water opossum Chironectes minimus in Atlantic Forest streams.Mammalian Biology http://dx. ABSTRACTThe water opossum Chironectes minimus is the world's only semi-aquatic marsupial. It is considered rare, and it is reported on several regional conservation lists of species as either endangered or data deficient. Given its uniqueness and the poor knowledge of its ecology, we aimed to investigate home range size and overlap and habitat selection of the water opossum in Atlantic Forest streams in southeastern Brazil.We radio tracked water opossums and collected information about their habitats and behaviour from October 2004 to April 2010. We combined common home range estimators for animals living in linear habitats with the synoptic model of home range and habitat selection. For the 10 individuals monitored, the home ranges varied between 0.80 and 9.66 km of watercourses; none of them had exclusive home ranges. The home range size for males was, on average, three times larger than for females. The overlap data showed that, on average, one male could encompass the home ranges of up to five females simultaneously, but more than one male could have access to the same female.For habitat selection at the individual level, we could not find any strong influence of habitat features on water opossum preferences because individuals selected different sets of habitat variables. However, at the population level, we found a negative relationship between home range size and river size. The water opossum seems to prefer shallow and narrow watercourses to establish its home ranges. Here, we present valuable information to advance our knowledge of the water opossum and its ecology, which is urgent for conservation purposes.

Use of highway culverts by the water opossum (Chironectes minimus) in southeastern Brazil

“…Here, records were more frequent in the dry season, but we could not determine the sex of the filmed individuals. Considering that the home length of C. minimus may vary between 0.8 and 9.6 km but few individuals have home lengths larger than 6.7 km (Fernandez et al 2015, Leite et al 2016, it is likely that the records reported herein represent at least two individuals.…”

“…Vehicle collision rate seems to be low for C. minimus even when compared with other semi-aquatic mammals such as the capybara (Hydrochoerus hydrochaeris) and the Neotropical otter (Lontra longicaudis) (Coelho et al 2008, Huijser et al 2013, Magioli et al 2019. A plausible explanation for the rarity of roadkills is that C. minimus seems to never leave watercourses during its daily movements (Leite et al 2016).…”

“…Most of the information on the ecology of C. minimus comes from studies carried out in Rio de Janeiro, southeastern Brazil, which have shed light on the home length, population density, use of shelters, and activity pattern of the species (Galliez et al 2009, Leite et al 2013, Fernandez et al 2015, Leite et al 2016. These and other reports show that C. minimus uses water bodies with sandy or stony substrates, fast-flowing water, and with well-preserved riparian forests (Palmeirim et al 2014, Voss et al 2001, Bressiani & Graipel 2008.…”

Moving far from water: unusual dispersal movement of the water opossum (Chironectes minimus: Didelphimorphia, Didelphidae) in central Brazil

“…At local spatial scale, the water opossum is potentially threatened by deforestation of riverine vegetation, contamination and deterioration of freshwater ecosystems (Pérez-Hernandez et al 2016). In Atlantic Forest, C. minimus has been described as highly sensitive to the degradation of riparian forest and riverine vegetation, preferring well preserved habitats such as streams and rivers with stony substrate, clear and fast-running water associated with a highly preserved riparian forest (Handley 1976, Galliez et al 2009, Palmeirim et al 2014, Leite et al 2016). However, the water opossum also seems to be able to occur in degraded habitats, with few studies showing that this marsupial is found in degraded riverine forests.…”

Movement behavior of the Monito del monte (Dromiciops gliroides): new insights into the ecology of a unique marsupial

“…Consequently, this behavioral expression largely determines animal fitness as well as its ecological roles in the ecosystem, considering that the environment is highly dynamic in terms of and resource availability [4,5]. Spatial behavior, therefore, may be strongly correlated to morphological (body mass), physiological (metabolic rate), ecological (intra-and interspecific interactions, diet and foraging strategies), social, and environmental factors [6,7]. Information on spatial behavior in wild animals is difficult to obtain (and particularly for cryptic species), but is important for understanding their home range, social interactions, mating systems and foraging strategies [8].…”