26 April 2010

Heuweltjies

I've been doing most of my camera trapping at Tygerberg Nature Reserve this year and some of you might have wondered where the name comes from. Well, the main theory is that is it comes from the Southern Harvester Termite.

From the City of Cape Town Nature Reserves booklet (online copy here):
"From a distance, the blotches visible on the hills of the Western Cape reminded Dutch settlers of a leopard's skin, and the hills became known as Luipaerts Berghen (1657). This was changed to Tijgerberghen in 1661, and is now known as Tygerberg. These regular round patches are called 'heuweltjies' or small hills. Many scientists think that heuweltjies are the remains of ancient termite nests. Harvester termites bring plant material into their burrows and over time they change the nature of the soil. As a result, the plants growing on heuweltjies differ from those in the surrounding veld."

Another site with some information about Tygerberg and the 'heuweltjies' can be found over here or check out the brief entry for 'heuweltjies' on wikipedia.

The spots are clearly visible from this Google Earth image

The Southern Harvester Termites are reasonably large. The soldiers have a body length of 7-13 mm and the workers are 6-8 mm long.

A Southern Harvester Termite (Rysmier) working in the late afternoon on Tygerberg hills

In soil with high clay content their mounds may become sharp and conical. At the base of the mound is a spherical hive with horizontal layers of chewed vegetable matter. The queen, king and nymphs live in the mounds. The mounds generally become covered in sand and form massive long-lived structures up to 20 m in diameter and 2 m high. These mounts are evenly spaced across the landscape (like all termitaria). The mounds are richer in nutrients than the surrounding area because of the pelleted feces and other waste that accumulate on the surface. These mounds are colonised by plants that favour disturbed sites and richer soils and can create remarkable patterns in the landscape.

Workers dragging twigs onto the heap at one of the entrances

Workers forage in large numbers by day and prefer woody plants. Plant twigs are cut and dragged to temporary storage areas around the foraging ports. The termites avoid fynbos and sandstone areas, but are common in more open veld.



References:
Picker, Griffiths, Weaving (2004). Field Guide to Insects of South Africa. 2nd ed. Cape Town: Struik Publishers. 54.

6 comments:

  1. Have you been thinking of CTing a termite mound? Might get some nifty pictures of freeloaders. Alan Root's film about termites and termite mounds had some mighty amazing footage.

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  2. Being a plant geek too - this is really, really interesting. Definitely more interesting than the Codger's speculation about the connection between grass clump height and cow pies the last time we were wandering the fields of Chimineas! :)

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  3. @Codger:
    Yes, I have been keeping an eye open for a nice termite mound. I stumbled upon one with some old marks from digging, but the site was not ideal and didn't convince me that it will be a very rewarding camera set. So, I'm still searching for a good spot with termite activity. (As far as I can tell the mounds at Tygerberg aren't very tall, although they seem to be pretty wide...)

    I haven't seen the Alan Root movie, will keep an eye open for it, thanks.


    @RandomTruth
    Glad you enjoyed it. I'm not too sure about the stats that are going around (especially the number for the mammals) but Tygerberg should have around 460 plant species, and its size is only 300 hectares. Its one of the last pieces of Swartland Shale Renosterveld and very threatened. The area around here is extremely rich in plant species (Cape Floral Kingdom).

    I'll try and do a post that focuses a bit more on the plants and vegetation of this area some time in the future.

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  4. Some amazing shots here Henry. No better place to be then the outdoors, camera in hand. :)

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  5. "The area around here is extremely rich in plant species" - what an understatement Henry! I think 1/2 the cultivated plants in America come from that area! Especially in California, because we have similar climates. :)

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  6. Ha ha ha ha!! LOL, well I did say "extremely rich" :P

    Thanks for all the comments from you and the Codger, I really enjoy them! :)

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