18 January 2010

Keeping Company with a Shrew

It is difficult to identify many small mammals when all you have is a "bad" photo. Distinguishing between the different Vlei Rat species is proving difficult, and the fact that different books have different opinions does not help either... Sometimes it gets very tricky to identify beyond genus level. Having the animal in your hands makes it allot easier, but using camera traps one doesn't have that privilege.

Vlei Rat (Vleirot) nibbling on a plant in front of the camera


It is easy enough to assume this is some Vlei Rat species, but which one? In the end I decided to base my decision on The Mammals of the Southern African Subregion by J. D. Skinner and C. T. Chimimba (3rd Edition). The book seems to be reasonably up to date and have a very scientific approach to describing all the mammals in the region. Based on the description and distribution information I would say that this is a Vlei Rat :)

Now, you are forgiven if you think that I might be repeating myself, but actually all members of the genus Otomys are referred to as being "Vlei Rats", but there is in fact also a species called Vlei Rat (Otomys irroratus).

These pictures are a bit out of focus because the animal is sitting to close to the lens


Vlei Rats have a total length of about 24 cm of which about 9 cm is its tail. They weigh approximately 120 g and have a robust stocky appearance with a short tail and a blunt face. They are densely furred with a shaggy coat. The fur is dark but the colour varies geographically. The ears are large and rounded.

video

Video: Vlei Rat from behind...


Vlei rat's are usually associated with moist, marshy habitats, but can also be found in drier habitats. They have a wide distribution but are more common in habitats associated with damp soil (vleis, along streams or near fringes of swamps). They can be found at considerable distances from water.

They live alone, in pairs or in small groups. They are terrestrial, only entering water when forced too. They are crepuscular (active during dawn/dusk) with some diurnal (day) and nocturnal (night) activity.

Vlei Rats are wholly herbivorous and show advanced specialisation of the digestive tract. They eat plant shoots and the stems of grass, sedges, reeds and other plants. They have a low metabolic rate and low overall minimum thermal conductance. This helps them to adapt to their habitat and habits.


References:
Chris & Tilde Stuart (2008). Veldgids tot Soogdiere van Suider-Afrika. Kaapstad: Struik Uitgewers. 130-131.
John D. Skinner & Christian T. Chimimba (2005). The Mammals of the Southern African Subregion. Cape Town: Cambridge University Press. 171-173.

2 comments:

  1. Congratulations on your blog, Henry. It's good to see your photos of small mammals, so often ignored by camera trappers, and to read the mammalogy. You are now on my blog roll. Keep the posts coming.

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  2. Hi Codger

    What a surprise to find that somebody left a comment on my blog, and even a bigger surprise that it is the Camera Trap Codger himself. I've been reading your blog for a long time now and enjoy it allot.

    I really enjoy photographing the small animals. They are sometimes more difficult to track down than some of the bigger ones. I always wish I had more time (and cameras) to get pictures of the more elusive/difficult animals, but then again the challenges are part of the fun of camera trapping.

    Thanks again for your comment, I'll try to return the favor sometime :)
    Henry de Lange

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