#rodentblr

Rodents two days in a row? Sure, why not. This is Natterer’s Oecomys (Oecomys concolor), a rodent from northern South America, specifically the Rio Negro West region of northern Amazonia. They have a head and body length of 12.5 cm and tail length of around 15 cm [1]. The image above is actually of a non-specified Oecomys, but that is just because I was unable to find any images specifically of Natterer’s Oecomys.

Especially older information regarding them is difficult to assess, as for a long time, many species were lumped under their name. In 1960, Philip Hershkovitz consolidated 25 different species just under O. concolor and O. bicolor. This means that any studies on them around this time may very well have been studying other rodents [1] and many gene sequences labelled as Natterer’s Oecomys in gene databases come from far outside the range we accept for them now [2]. In general though, Oecomys appear to be specialised to live in trees, and while no detailed dietary research has been done, they have been claimed to eat primarily fruits and grains [3].

Natterer’s Oecomys was first proposed as a species in 1848 by Johann Andreas Wagner, based upon an individual caught by the titular Johann Natterer. The uniform “beautiful white” of their stomach which impressed Wagner and led to the species name is not actually very representative of the species as a whole. There have been several of Natterer’s Oecomys (within the narrower definition we use now) who have grey stomachs with hair which may even have buffy tips, making their species name somewhat ironic [1].

Above you see the Australian Swamp Rat (Rattus lutreolus), and below you will see information on them. They can reach a body length of up to 20 cm with a tail of 14 cm and are found in eastern mainland Australia and in Tasmania [1].

They were initially described as a water-loving species (and thus given the name lutreolus, meaning little otter), but their main habitat association is actually just dense green vegetation. Ironically the Tasmanian populations even avoid swimming and prefer to keep dry. In this vegetation they will build conspicuous tunnel systems and runways by gnawing and burrowing beneath the surface [2]. They select their habitat by prioritising density, with females occupying the best areas [3]. Females tend to act aggressive towards males outside of the summer mating season [4].

Through the use of these networks, they can protect themselves from aerial predators even during the day [3]. They can then use this advantage to modify what time of day they’re active based on other rodents. While they naturally gravitate to being nocturnal if they’re all alone, their activity patterns shift to twilight and daytime when other, more strictly nocturnal, species of rodents inhabit the same area [5].

Australian Swamp Rats primarily feed on plant stems, however their diet also depends heavily on the availability of other plant materials (and on occasion fungus and insects). For instance, in heath habitats there is little else available for most of the year, but once seeds pop up in spring and early summer, they’ll gladly have those as well (and the additional energy may be why they breed during this time [6], as they can, in theory, breed year round [4]).

There are some threats to them described in the literature. For instance, they do not respond as fearfully to the scent of invasive predator species such as the Red Fox (Vulpes vulpes) or feral cats (Felis catus) as they do to native predator species like the Spotted-tailed Quoll (Dasyurus maculatus) [7]. There has also been some destruction of their habitat “by fire, by grazing by domestic animals, and by the direct hand of man” [2], but overall they are still very common and seem to be surviving quite well as a species, and so are categorised under Least Concern by the IUCN [8].

All of our currently available hamsters & mice at Tiny Whiskers Animal Rescue in Minneapolis. We are a 501c3 small animal rescue.

All of our currently available guinea pigs and rats at Tiny Whiskers Animal Rescue in Minneapolis. We are a 501c3 small animal rescue.