The joys and tribulations of a field biologist (and hermit) studying
mongooses in the South African bush.
Friday, March 26, 2010
Come into my parlour...
At this time of year, I don't envy flying insects.
In truth, I don't envy them anytime, but now, at the end of the wet season, their lot is particularly grim. The bush is brimming with orb-web spiders.
Tier upon tier of vast, disc-like webs tremble between every tree and bush. Each web spans about 1.5 m and shimmers golden when viewed from the side. A stroll through my study site leaves me feeling like Frodo in the tunnel of Torech Ungol.
The most common species is the massive golden orb-web spider, Nephila senegalensis. The females are daunting, with a body 25-30mm long (add legs and they're larger than my spread hand). They weave a web so strong it ensnares small birds (I released a struggling blue waxbill recently). Fortunately, they're harmless to humans and flee rapidly when their web is blunderingly destroyed, so the pitter-patter of scuttling feet on one's face lasts only a second or two.
Golden orb-web spider, Nephila senegalensis.
The golden orb-web spider is named for the colour of its silk. This is the patch of silk at the centre of the web.
An altogether more clinging species, is the black and yellow garden orb-web spider (catchy name, huh). It is also very large (25mm body) but is a bit less common.
Black and yellow garden orb-web spider, Argiope australis.
You can see the zig-zags of white silk (called stabilimenta) that span its web, forming a cross at the centre where the spider hangs. The function of stabilimenta is still hotly debated, but these decorations may camouflage the spider, breaking up its outline, attract insects by imitating the ultraviolet runways of flower petals, or warn blundering vertebrates of the presence of a web.
From my point of view, the little (8 mm) yellow and black kite spider is relatively inoffensive because it usually strings its web a couple of metres above the ground.
Yellow and black kite spider, Gasteracantha versicolor.
Having spent 16 years living in remote places in the African bush studying the social behaviour of mongooses, my own is non-existent. I survived 8 years in the desert, at the Kalahari Meerkat Research Project (i.e. Meerkat Manor), and am now doing research on dwarf mongooses in the lowveld of NE South Africa.
If you come across a mistake on this blog, please let me know. I really want to learn new things, and to get them right!
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