Seeing these elusive creatures: Small mammal trapping in Renosterveld

Seeing these elusive creatures: Small mammal trapping in Renosterveld

By Odette Curtis-Scott & Grant Forbes

There are some creatures in Renosterveld that are barely ever seen with the naked eye, and if they are, they are a mere blur as they rush past you while you walk through the veld. This is especially true for our shy small mammals: essentially the mice, rats and shrews that inhabit our shrublands.

Above: Cape Rock Sengi / Elephant Shrew, an endearing creature with a large round body and big eyes. They are not closely related to other shrews or rodents, but are in fact closer to hedgehogs. They are mostly insectivorous, and due to the nature in which they forage for invertebrates amongst flowers, they are also important pollinators of some species, including some Massonia, Hyobanche and Proteas.

Because these creatures are generally so elusive, and several are also nocturnal, the only way to account for their presence is to set live traps for them. These traps are baited with various baits, including peanut butter-and-oat balls or droëwors, and set overnight, at pre-determined distances apart (e.g. we will set a line of 20 traps, each spaced 5 m apart).

In the morning, we check the traps and make a list of all the small mammals we find. We then photograph them (or try to) – that is the fun part and can be quite challenging, as some escape before we get the chance to focus our cameras, while others pose very obligingly. All are released once they have been photographed.

Above: Karoo Bush Rat, the ‘vlei rat’ of the drier regions of South Africa and Namibia and has adapted to these arid environments.

Our gratitude to the Fynbos Trust

The Fynbos Trust recently supported the ORCT with the purchase of 40 Sherman traps – specialised traps for live trapping small mammals (for research purposes). And we tested them out over a weekend spent with the Spider Club of South Africa members at our Haarwegskloof Renosterveld Reserve, with great success!

Average trapping rates are generally extremely low in most areas (4-7% is considered average globally). So we were thrilled with a success rate of 30% across all four traplines which we ran over two nights (one had a success rate of 45%!).

Above: Pygmy Mouse, one of the smallest rodents on Earth, weighing just 3 to 12 g.

Above: Striped Field Mouse, a common inhabitant of many Fynbos and Renosterveld systems and occurs through much of sub-Saharan Africa.

In total, we recorded five species:

  • Striped Mouse (Rhabdomys pumilio), the most common species;
  • Reddish-Grey Musk Shrew (Crocidura cyanea);
  • Karoo Bush Rat (Otomys unisalcatus);
  • The minute Pygmy Mouse (Mus minutoides)
  • And the highlight, the endearing Cape Rock Elephant Shrew / Sengi (Elephantulus edwardii).

We have also previously recorded Cape Spiny Mouse (Acomys subspinosius), Forest Shrew (Mysorex varius) and Namaqua Rock Mouse (Micaelamys namaquensis) at Haarwegskloof…. A nice diversity of small mammals, which is likely to be even higher (there are several species which do not come into Sherman traps).

Above: Namaqua Rock Mouse, this nocturnal mouse is a communal species. It’s also an omnivore, feeding on seeds and insects. In fact, this species acts as a seed disperser, helping to regulate the nutrient cycle of soil. 

Above: Cape Spiny Mouse, a mouse that is largely reliant on the Cape Floral Kingdom, especially Fynbos and Renosterveld. It’s unlikely to occur in modified habitats, rather favouring Fynbos seeds, as well as insects and snails. 

A valuable addition to our bioblitzes

We look forward to many more trips in the field with our new Shermans and would like to thank Chris Martens of the Fynbos Trust for supporting this initiative. These are going to add significant value to our bioblitzes and veld monitoring surveys in future!

Chris is also a special advisor to the ORCT board and a mentor to the ORCT staff and has guided and mentored us on numerous issues. We are extremely grateful and honoured to be working with such a wonderfully knowledgeable, experience and generous person!

Above: Reddish Grey Musk Shrew, a tiny (weighing about 12g) and feisty nocturnal predator of invertebrates, including insects and earthworms, spiders and centipedes.