Gobabeb is a unique
crossroads for a wide variety of people, from all over the world, at all points
during the year. Besides the hundreds of students that visit the Station every
year, the Station staff is also joined by different researchers – just in the
past few weeks we’ve had researchers from as far-flung as Oxford University in
the UK and as local as the University of Cape Town in South Africa – and a
growing tide of tourists, curious about what this ‘oasis’ is doing out here.
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| Unanticipated office visitor |
Dancing Spiders and TAOS Fellows Last Friday morning, I had an unexpected visitor
waiting at our office door. Well, more accurately on our office door. Chris (also referred to as Woody; my co-fellow
here at GBB) was less-than-thrilled to have a surprise encounter with the
Dancing White Lady Spider, as he was performing weather duties that morning. In
keeping with my promised role as Spider-and-Moth-Rescuer (Woody is not exactly
a fan of these flying, zooming, crawling things), I was called into action
first thing. Unfortunately for Woody, any removal processes were immediately
delayed when I saw what kind of spider we were dealing with – I had only just
been reading and writing about the Dancing White Ladies the other day, so to
see one pop in for a visit in such a timely manner was a welcome surprise! You
might even say spying the Dancing spider set me off in a jig of my own…
As you can see from the
photos below, the Dancing White Ladies are a pretty sizeable spider –
especially for we Northern Hemisphere dwellers, used to itsy-bitsy spiders and
daddy-long-legs – our office visitor was about 10cm across at her widest point!
They belong to the general “huntsmen” spider family – meaning they’re
formidable hunters, noted for their large jaws and often tipping towards the
larger and heavier end of the spider size scale.
The Dancing White Lady
Spider’s claim to fame is two-fold: first, they have a notably unique mating
ritual/habits, and secondly, they have remarkable, and still not
well-understood, navigational capacities. Here at Gobabeb, one of our former
Centre directors Joh Henschel did much of the ground-breaking behavioral
studies on DWLS (as well as a number of other insect species around the
Namib), in a little enclosure now featured in our Nature Walk called Spoon
City.
The Story of Spoon City begins with an inordinate number of available green
plastic spoons, apparently. A spider-friendly spot in the low dunes just on the
other side of the Kuiseb channel was found, dubbed “Vishnara”, and the first of
many essential spider studies began in 1986ish. Over the course of 101 morning
observation sessions, Henschel et al
found 261 spider burrows – little sandily-weaved trap doors – marking them with
a spoon approximately 15 cm from the entrance, creating the visual phenomenon
of a (seemingly random, to the untrained, non-research oriented eye) dune field
of spoons. At peak spider activity (which varies seasonally, October – February
being high sighting season), there were more than 750 spoons over a 600
square-meter area! The spoons weren’t just decoration, of course – Henschel et al were investigating burrow
abandonment: who, when, how often, and why DWLS abandoned burrows. They also
tested some other behaviors of the spiders, including territoriality and prey
responses (involving affixing beetles to sticks and awaiting response.
Whoever said research was uninteresting didn’t look too hard into arachnid
research, hey?).
The many burrow-hunting
mornings and spider-trap fanangling led to some fascinating insights
about these beautiful strong-mandibled spiders. Henschel et al found that most DWLS kept relatively local ranges (rarely
ranging further than 60-80cm from burrow entrance) and practiced their own form
of “door-keeping” – a ‘lazier’ form of hunting wherein the hunter eats whatever
prey happens to walk by at the ideal moment. In investigating those
navigational skills – DWLS are able to cut the most efficient path back to
their burrows, regardless of how far or aimlessly they have wandered from it, a
unique trait for arthropods – they even affixed mini-dataloggers with infrared
beams (!) onto some of the spiders. Although many a wandering path and track
were followed and logged, there were no absolutely-conclusive explanations for
these navigating feats, however the DWLS superior range of eyes are suspected
to play an important role in enabling their knack for navigating.
Their other claim to animal
fame is the source of their name: you knew ‘dancing’ had to come in someplace!
The Dancing White Lady Spider is so-named because of their mating rituals. Male
DWLS emerge from their burrows in pursuit of a female’s burrow, using those
impressive navigational skills as they trek around the dunes, sometimes several
hundred meters or even kilometers from the safety of their own burrows. Once
they have found an audience, they perch atop the burrow and begin their
performance – drumming their bodies and tip-tapping their eight legs in a
precise ploy for the lady-Lady’s heart (rather than her appetite). Upon
completion of their dance, the males await the females’ response – if the dance
proved worthy of accolade, the male is rewarded with the chance to mate; if he
has drummed the wrong note, then he has danced his last jig. Which will it be?
Sadly for the males, it is
bound to be their last performance either way – if the female is adequately
impressed, even the reward of mating is followed by her feeding on the male.
The prize is the chance to mate, the price paid is the male’s life either way –
it’s just a question of whether he gets his money’s worth. Sometimes the males
will escape with their lives, but the females are just a bit heavier than them,
often giving them the upper-hand (leg?).
These spiders have
long-featured in Gobabeb’s regular goings-on, most notably while Joh was at the
helm. The research section conducted annual spider censes in October and
November, before any reproduction skewed the population numbers, for long
enough to leave traces of it on our magical GBB Server/the source of all
Gobabeb (recent) history. Between my newfound fascination with these remarkably
graceful and awe/fear-striking arthropods, and the lucky discovery of a genuine
Joh Henschel Spider Trap in the fabled Room 42 (a less-than-orderly reliquary
of research projects of yore), I am hopeful that we might be able to see a bit
more of these spiders in the future. Hopefully in the field moreso than the
office though – for their sakes as well as Woody’s nerves!
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| Shower interrupter, regular interloper |
Going a bit batty… After the Dancing White Lady Spider heeded the call set out by my night hike research, I was soon visited by another subject of the hike: (what is most likely, but not definitively) the Namib long-eared bat, Laephotis namibensis. I say ‘not definitively’ because as it is now, we don’t really know enough about the Namib long-eared bat to say anything definite. There have been very few studies focusing on this species, even given its relatively recent discovery. It was among the fresh faces found during part of the Smithsonian Institution African Mammal Project, when a team of researchers led by Ronald E. Cole set up mist nets at a very young Gobabeb in 1963 to survey the diversity of mammals found in this stretch of southern Africa.
Since being discovered, we
have learnt very little about this cute-faced, big-eared winged mammal. It was
caught during several bat censes performed at Gobabeb during the 1980s, but
remained largely undescribed and its behaviors are entirely unknown. Existing
knowledge consists of a basic idea of species range (it has been caught in
parts of the Western Cape region in South Africa), and some idea of higher
activity time – it is most often caught over bodies of water and is a ‘late
flier’, caught closer to 21-22h at night rather than other bats caught at dusk.
We don’t even know where these bats live – our best guess is that they may shelter
underneath the bark of Camelthorn and Anaboom trees during the day.
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| That cute little face! How could you not want to study this little one? |
That is, when they’re not sheltering in Gobabeb bathrooms. These bats seem to like frequenting the bathrooms at our fair station – in particular, the Old House bathroom in the courtyard, and, more recently, the women’s bathroom at the Station. In fact, when I indicated my interest in seeing one of the bats to my colleagues, I was directed to the OH bathroom as the premier bat-viewing site. And indeed, it was in the OH bathroom that I got my first chance – another morning begun by getting a closer-look at one of our winged/many-legged neighbors. I took my time getting some shots of this shower-interloper, as I had found out during my research the difficulty in finding good photos available of the Namib long-eared bats. I also wanted to get a good collection of bat photos for our quickly-arriving newest researcher, Angela, who will be studying bats around Gobabeb. At long last, our bats are primed to receive the attention they have long been denied – and hopefully I’ll get a positive ID on this little guy/girl/bat!
Snakes on the Plain(s) My next nocturnal visitor also had me dancing and
running for my camera – albeit in a bit more panic than excitement than my
previous two neighbors had. It was while I was on weather duty, and at the end
of a long week, that I encountered my first snake here – and at a bit too close for comfort’s proximity – just
outside of Old House. Doris and I had just decided to take an evening trek out
onto the Gravel Plains to release a beetle caught that morning in the pitfall
traps, which had, at the time, convincingly played dead. Seeing as I had to do
evening weather duties anyway, we ventured out together. Just as we were
leaving the Old House veranda, the concert began – suddenly Doris is hopping
and yelping, I am oohing and aaahing, and the snake (THE SNAKE?!) is huffing
and puffing.
In the
paralyzed-yet-adrenaline-fueled moments that followed, I snapped a few entirely
dark photos as Doris started frantically seeking snake-bite-marks on her
flipflop-clad feet and the snake slunk into the shrub still seething. While I
know that people’s generally inflated fear of all snakes is somewhat
unjustified, I can honestly tell you that the noise made by puffing adders is
absolutely, awesomely terrifying. It is a kind of wheezing-through-teeth which
is surprisingly loud once the size of the snake is sighted. We, of course,
surprised the snake as much as it had surprised us – it and Doris had mirrored
each other in leap-like motions, the snake squirming in mid-air as if in
response to Doris’ squealing.
This jumping is apparently not
out of character for horned adders, noted back in 1988 at, you guessed it,
Gobabeb. Other fun facts about horned adders unearthed from Gobabeb’s wonderous
library: horned adders are, amazingly enough, not immune to their own
venom. This was discovered after several snakes were bungled together for
transport back to a terrarium, and two died within a day of their arrival,
sporting distinctive puncture-marks. These snakes were also noted to be
particularly active in the evenings, despite earlier suspicions of mostly
diurnal (day-time) activity, making our sighting all the more likely to be a
horned adder.
Our unexpected third resident of Old House that evening was likely a
horned adder, which are rarely known to bite. That puffing noise was, however,
its way of warning us that it was prepared to do so if we were threatening with
the bottom of a shoe. It was likely out and about because, as I had eerily
noted just prior to our encounter, it was an unusually warm night. Snakes are
also known to frequent Old House, given our (literal, and unofficial) open door
policy and our renown as a gathering place for rodents. Luckily for me, our
most recent set of (human) residents worked hard to rid OH of its pesky furry
snackers making OH a less inviting temptation for wandering snakes.
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| A probable horned adder slithering over the rocks. Not pictured: Doris and Meg squealing/leaping in foreground. |
