May 2019

MAY 2019

The month of May, the end of autumn and the beginning of winter, has come and gone. During the month sunrises have moved well into the morning and the temperatures have plummeted. It all seems so sudden. But still, we have not had many white mornings with frost covering the ground and it still gets nice and toasty in the middle of the day. And I still managed to encounter a whole bunch of interesting little critters while out there doing my work. Below is some of those that I managed to photograph:

A Black-legged Golden Orb-web Spider, Nephila fenestrata, photographed at the entrance to the Steenkamps Waterfall walk, is well known from the sub-tropical lowveld but not so much from our temperate climes. The massive orb webs they construct can be up to 1,5 meters in diameter and have a distinctive golden silk. They spend their entire time on the web and with the web being so large and the spider around 100mm from leg tip to leg tip that they are exposed to potential enemies more than would be the case for most spiders. To mitigate this, they construct barrier webs on either side of the main orb to make it more difficult for predators to reach them. The hub of the web is the top half of the orb, while the bottom half consists of the ensnaring sticky strands. Carotinoids and others are responsible for the golden colour of the silk and experiments reveal evidence that suggests that sunlight reflecting off the golden silk is attractive to bees. Also, the spiders can reduce the intensity of the pigment, so in shaded areas they spin webs that are more camouflaged with the background foliage, to the vision of potential prey insects because the spectral reflectance of the silk is within the particular range of insect vision. The silk also loses its stickiness with age, so the spider has to spend much time constantly maintaining its web. The old silk is consumed by the spider while she spins new strands to replace them. I remember when I was guiding in the lowveld, I used to tug on the support strands connecting the orb to the surrounding trees to show my guests just how strong the silk was as they watched even large branches sway! In fact, from 2004 to 2007, a shawl was made from the silk from 1.2 million spiders that were collected from the wild and released again a half an hour later, after they had produced their silk. Then in 2012, a cape was added to this and these garments were exhibited at the Victoria and Albert museum in London. Google these. You will be impressed by the beauty of the garments! Now, when you encounter these webs, there are usually other, smaller spiders on them. These can either be males of the species or a different  species altogether. The male Golden Orb weaver spiders are much smaller than the female and after reaching maturity, they leave their webs and find a female's web which usually has other males present already. they then compete until the most dominant male is there to mate with the giant female. Otherwise, if the other spiders are black and silver, then they are from the genus Argyrodes and they are there to feed off of her captured prey. They are kleptoparasitic. Like the government...

Gee, how beautiful is this moth with feathers. I had to disturb it to get it to spread its "feathers" but normally when at rest they are closed tightly together which makes the wings look like sticks. This, together with the long, spindly legs with branch-like protuberances camouflages the moth expertly in its grassy habitat. so, essentially, the Plume Moth, from the Pterophoridae, has fold-up wings.

If you've been up high on the Estate where quartzite boulders dominate, you'll be familiar with the bright orange crustose Lichens growing on them. This is called Firedot Lichen, Caloplaca cinnabarina. As mentioned in previous blogs, Lichens are a group of living organisms made up of a tight symbiosis between a fungus and an algae or cyanobacteria. The fungus attaches the organism to the substrate and can even dissolve some minerals from it. The algae or cyanobacteria provide the organism with carbs produced by photosynthesis and they both absorb water. The mycobiont (the fungal part of the organism) produces spores and reproduces like other fungi but the spore has to meet up with compatible algae before a lichen is formed. Lichens are also very long lived and according to Wikipedia, the longest living organism was a lichen dated at more than 8000 years! Now, in my blog of November 15 2017, I introduced you to the endemic Drakensberg Crag Lizard, Pseudocordylus melanotus. This lizard has bright orange streaks and patches on its body that camouflage it perfectly in its habitat that includes Firedot Lichen. One can figure who came first. 

On May day I accompanied the Moores and Van Heerdens on a hike around the amphitheater on the eastern end of South Valley, when we encountered a very grumpy little Berg Adder, Bitis atropos, on our pathway. I'm sure you are all very aware of these little vipers because they are one of the more common snakes encountered on the Estate, especially at higher altitudes. We do, however, have two different colour morphs of the species with the typical one being a charcoal grey with pale-bordered black patches. The less typical colour form, which happens to be more common here, is like the one above, plain pale brown with no markings. I have seen both colour forms within 500m of each other and have also seen pale brown ones, like this, but with markings. Although there has not been a recorded human fatality from a bite from one of these snakes, the Berg Adder is unique among the vipers in having a neurotoxic venom like that of Elapids (Mambas, Cobras and others) and unlike the Cytotoxins carried by all the rest of the vipers. It has been suggested that this is due to the habitat where prey can escape easier because of large boulders and cliffs etc. Neurotoxins are much quicker acting than cytotoxins, so the prey item is subdued in a much shorter time-span. Unlike the Elapids, though, the nerve affecting venom of the Berg Adder does not seem to affect cardiac and pulmonary functions that make elapid venom so dangerous. But, on the negative side, the venom is not neutralised by antivenoms made today, so envenomations have to be treated symptomatically. The symptoms of a bite have been likened to severe alcohol intoxication and bizarrely, some victims have suffered these symptons for many months, with some having permanent damage. As you can imagine, those symptoms wont fair well for a mountain climber, who will probably fall before getting to safety!     

A young Striped Skink, Trachylepis striata, emerges from the grass by my patio. Found pretty much everywhere on the Estate, from the river thickets hugging SPK 2 to the summit of Mount Anderson. A nimble little predator of small to medium insects, the Striped Skink also faces a wide range of enemies. From the crow-like Red-winged Starlings to the Drakensberg Crag Lizaed mentioned earlier. And, it also happens to be the preferred prey item of the little Bergie featured above. But it has a defensive mechanism that is particularly effective against the first two predators mentioned but not from the adder : it can drop its tail and while the predator is confronted by this wriggling distraction the wily little skink runs off to live another day. the tail re-grows, although not as long as the original.

When laying her eggs, the adult female Lacewing excretes a sticky fluid from the tip of her abdomen, touches it to the substrate and then lifts her abdomen away from the substrate, stretching the sticky fluid into a thread, which hardens quickly in the air. She then proceeds to lay one egg on the end if this thread so that it resembles a miniature helium-filled balloon on a string.She repeats this exercise till her batch is laid. In spring and summer she will lay a batch of eggs on a plant that is infested with aphids, the small bugs that suck the juices of the plant. Her offspring are voracious predators of these aphids and are not adverse to cannibalism either, necessitating the mother to lay her eggs on a stalk, to help keep the offspring away from each other upon hatching.  In the previous blog I showed a photo of a Ladybird eating aphids, and explained that their larvae eat them as well. Well, these larvae resemble Ladybird larvae and can often be found together with Ladybird larvae in among a colony of aphids. In the instance of this photo, at the end of the season like it is, the Lacewing would lay her eggs on or near a plant that is attractive to aphids and hope that aphids are present the following spring after the eggs have over-wintered and then hatched. The adult of this species is bright green with big shiny eyes and delicate wings like other members of the Neuroptera order of insects. Another member I have posted about in previous blogs is the Ant Lion, whose larvae dig cone-shaped pits in soft sand.  

My little camera is no good at taking distant shots so this is a poor shot but a photograph nonetheless. In the centre of the frame is a Sable Antelope, Hippotragus niger, and at the top is an Eland. On the 15th Don called me on the radio early in the morning and asked if I had ever seen Sable here before. I hadn't, except for the breeding projects in Rivendell. So I rushed out and got to see this Sable just above the old road opposite K9 that is now the end part of the Rock Kestrel Trail. Trent Sinclair, from Mount Anderson Ranch next door, said he sees one on his place that was not there at the time so this must have been it. Very exciting and a new species for me to add to our mammal list here on the Estate.

While burning the firebreaks this month we stumbled upon a Thick-clawed Scorpion, Opistophthalmus sp., that crawled out from under a rock that we had disturbed. The venom of the scorpion is rather weak and that is why the pincers are so large and powerful, so that it can subdue its prey, small to medium-sized insects, quicker than the venom will allow.  So the general rule is: If the pincers are large and the tail is thin, then the scorpion is less harmful but if the pincers are small and tha tail is thick, then it is more harmful. The above Thick-clawed scorpion's sting is not worse than a bee sting but it can still give you a painful nip with those big pincers.

A nice close-up of an Orange Acraea, Acraea anacreon, resting on the autumn bloom of a Tetraselago wilmsii. Because of the toxins carried in the body of the butterfly, it is a slow and sluggish lepidopteran that is commonly encountered in the autumn months throughout the Estate, at all altitudes. The larvae feed on the small, needle-like leaves of the very common River Rice Bush, Cliffortia linearifolia from the Rose family and Aeschynomene bushes from the Pea family that are also common along the rivers' edges on the Estate.

A Mountain Malachite Damselfly, Chlorolestes fasciatus, perched above the water on the look-out for prey, has a DBI of 4 (see Jolly Season 2018 blog). Prey consists of small flying insects like flies, lacewings and mosquitoes that are caught on the wing near the waters edge. The bronze body colour of this individual tells us that it is old. With a life expectancy not exceeding 5 weeks, this one is maybe a little older than a month. The larvae of Damselfies are also predatory but they reside and catch their prey under water where they are a  common prey item to fish, especially Trout. Most wet flies, used in fly fishing, are made to resemble a Damselfly larva. 

This miniature little moth-like insect is a Caddisfly from the order Trichoptera. They are closely related to Moths and Butterflies from the order Lepidoptera which means "Scaled-wing".On closer inspection, you will see that the wings of the Caddisfly are hairy, not scaled  like the moths. Trichoptera means "Hairy-wing". Like the Damselfly larvae before this, the Caddifly larvae also reside under water, but they use silk and sand grains, twigs or other debris to construct a protective mobile home which helps protect them from fish, although they are still relished by Trout. Dry flies used in fly fishing are often made to resemble an adult Caddisfly. Another big difference between Moths and Caddisflies are the mouth parts. Moths have a long, coiled proboscis while a Caddisfly has reduced mouth parts or, like this species, a broom-like appendage to sweep up micro particles. The above species has a characteristic tight S-shaped dance that it performs on the floor while it sweeps up its food.

Even though the grasslands are  more drab as we enter winter, there are still some lovely flowers out there. This is a Hesperantha baurii found among rocks in our grasslands at higher altitudes. If the flower seems familiar to you, it is because it is very closely related to the Scarlet River Lily, Hesperantha coccinea, which is much redder, a bit larger and grows on the waters edge at lower altitudes.

Ryan Nicholson, Charles Van Heerden and Scarlet Moore pose on the newly opened path leading to the Olinia gorge summer waterfall. They completed  some community service work for me by clearing the path from its junction with the Rock Kestrel Trail until it sinks into the Afro-temperate forest in the gorge.The new Olinia gorge walk starts at the starting point for the Rock Kestrel Trail in South Valley and forks off it 600m from the beginning. Instead of turning left to continue on the Kestrel trail, you carry on straight on the new path and after a further 300 meters you will enter the forest. Once you reach the river line, you will turn left, uphill, and a further 200 meters on you will find yourself at the base of a beautiful waterfall which is just a trickle right now, but flows strongly in the rainy season. Once you have enjoyed your time at the waterfall, you will turn around and head back downstream to the parking, in the gorge for most of the way. So from the parking to the waterfall and back to the parking is a 2,5 kilometer circular hike, less demanding than the Steenkamps Waterfall hike. Olinia is the genus name for the Mountain Hard-pear tree, Olinia emarginata, which is very well represented in the gorge and is most certainly one of the most beautiful trees found on the Estate.

And to finish off, a photo of a Ragwort plant, Senecio sp., covered in ice. Even though it has not yet been too cold here yet, we have still had some cold mornings, brrrrrr!

Winter is here but it wont be for long. Get here before it's gone and enjoy some crisp early morning activities from Fishing to cycling, running or hiking.