JULY 2020

JULY 2020

With the relaxation of some of the restrictions put in place to control the Corona virus, we have seen many members on the Estate during the month of July. July, traditionally a cold, windy month, was no different this year but still produced spectacular white grassland scenery like the above shot facing north from the southern part of the Rock Kestrel trail. And probably the most inactive month of the year concerning wildlife, I still managed to encounter a prolific array of interesting and exciting stuff. Below is a gallery of some of these:

Brrr. It has been a very cold July with some mornings so thick with frost that it looked like snow covering the ground. I found these beautiful ice structures beside the crossing into Hidden Valley from the Kliprots road. I think the curvy structures are formed when the spray from the water tumbling over the rocks freezes and builds up on itself like an ice stalagmite in a cave that is formed by freezing water vapour. If you can help with how and why these structures, which reach up to 10 centimeters high, are formed, then leave a comment at the end of the blog and let me know your thoughts. However and whyever they are formed, I'm sure all can agree that it has to be very cold (for us spoiled South Africans)!

 

During the month of May, I posted a blog highlighting the succulents one can encounter on the Estate. One of these succulents and certainly one of my favourites is the Bonsai Crassula, Crassula sarcocaulis. Since then, while high up above Rock Solid (unit 22) on the slopes at the base of Mount Prospect's peak, I found this spectacular rockery garden of them. Like epiphytes (air plants), as they are here, they are not growing in any soil but decomposing plant material and mosses on the rock surface. This also explains why they are all leaning as they have less anchorage to stabilise themselves against the strong winds experienced up there  Quite a treasure!

I stumbled upon this delightful little milkweed plant called Starred  Little Crowns, Brachystelma stellatum, high up on the rocks above Knife-edge Ridge in the very north-eastern portion of the Estate quite a while back, but only managed to identify it recently. It is an exciting addition to our plant list because it is classified as RARE in the National Red List of South African Plants. This is defined as a plant that
"meets at least one of four South African criteria for rarity, but is not exposed to any direct or plausible potential threat and does not qualify for a category of threat according to one of the five IUCN criteria. The four criteria are as follows:

• Restricted range: Extent of Occurrence (EOO) <500 km2, OR

• Habitat specialist: Species is restricted to a specialized microhabitat so that it has a very small Area of Occupancy (AOO), typically smaller than 20 km2, OR

• Low densities of individuals: Species always occurs as single individuals or very small subpopulations (typically fewer than 50 mature individuals) scattered over a wide area, OR

• Small global population: Less than 10 000 mature individuals."

In the Red List, they don't specify how many of and which of these criteria are met but I'm sure this species meets three of these criteria because: it is only found from Origstad Nature Reserve to Steenkampsberg and Long Tom; has low density of individuals (I only found three plants, very close together, in the whole area); and has probably represented by a small global population being endemic to such a small area on the planet. Fortunately, the populations are regarded as stable thanks to their habitat preference of high altitude rocky situations where development is unlikely to take place. The only threat I can think of is afforestation for timber production and that will never happen thanks to places like Finsbury Estate

Wow! This is the tenth species of ant I have so far identified on the Estate and five of them are from the same genus of Sugar ants (Southern Africa) or Carpenter ants (northern hemisphere). This is a Pale Yellow Sugar ant, Camponotus importunus, and this soldier was exposed when I accidentally shifted a boulder and exposed the secret entrances to its nest. They are scavengers of plant and animal material and the older workers emerge at night and search for food to scavenge (younger workers are put to work within the nest looking after the queen, cleaning passageways or tending larvae and pupae and only venture outside once experienced enough). They are very much attracted to sugars, syrups and honeys and if any of these are found (or any other scavengable material) the worker will take the shortest route back to the nest, leaving a scent trail of pheromones behind for the workers they are about to summon to follow back to the food source. These ants also frequently have multiple queens in a single nest who repel each other and reside as far from the others as possible within the nest. 

This is a carton nest, rather common but usually concealed amongst foliage in bushes and trees, constructed by a very different kind of ant, Cocktail ants, Crematogaster sp. The nests are constructed from pieces of chewed plant material mixed with saliva and is surprisingly strong. These are very aggressive carnivorous ants that search, in larger groups, for insect victims during the day. Once a victim is located, the locater runs around in a frenzy depositing excitable pheromones on the ground that attract others and they lift their abdomens forward above their heads (hence cocktail ants) and inject venom into the victim until it is subdued. The ants then carry the victim spread-eagled, to spread the weight evenly, back to the nest in a tree or bush. The ants have arolium which are pad-like lobes projecting between their tarsal claws. These arolium are critical in helping the ants to get the prey items to their nests high up in bushes and trees. The colonies, unlike the Sugar ants above, contain only a single queen but often have mature workers with functioning ovaries who sometimes lay eggs. These eggs are then eaten by the queen but if the queen dies, these workers can continue the colony for a limited time.

My team and I were working on the Pine along the northern parts of the Zebra trail when we encountered this Common Mole-rat, Cryptomys hottentotus.A very exciting encounter because they spend their time under the ground and the only sign of them we usually see are the little mounds of loose sand after they have cleared it from their subterranean tunnels. Although their eyes are extremely small and their eyesight very poor, this chap still saw us and when it did, it immediately lifted it's head and began grunting (pretty loudly!) and snapping those massive incisors together. Made me think of a miniature Hippopotamus! I wanted to pick it up to deposit it where I could photograph it easier but realised that it uses those incisors (unlike the Moles from the northern hemisphere that use their forelegs) to bite through the rocky soil when searching for food or building underground tunnels and rooms. Indeed, I found out afterwards that their skulls are specially adapted to house extra large muscles to enable this... good thing I didn't let it bite me... could've lost part of a finger. I did pick it up with my shirt and it immediately spun around within its skin to face me which I also learned later it was capable of to enable it to move around in its limited space underground (Honey Badgers can also move around within their skin). Another physiological feature of this subterranean mammal is that its incisors are exposed even when it's mouth is closed and its cheeks sealed which stops it getting a mouthful of soil while digging its tunnels. The social structure is also abnormal and is the genesis of eusociality: They live within a system where only one dominant male and one dominant female breed while the rest of the colony support them. The rest of the colony is usually made up of older offspring helping to raise their newer siblings (like in Porcupines and Jackals and many bird species - it is called an extended family) but immigrants are also accepted into the colony and depending on their experience and attitude will become casual workers or breeders while blood youngsters will be workers. Workers work about 20% harder than casual workers in the colony. The nest is made up of a system of permanent, maintained tunnels and chambers used for food storage and resting. They radiate out from this nest in tunnels to find food which is the roots, bulbs, corms of a wide variety of plants. They can even drag shallow-root plants through the ground into their tunnels and feed on the leaves and stems! Smaller food items are eaten in situ and larger items are carried to storage chambers and stored for later consumption. One colony studied in the Western Cape had a network of tunnels exceeding a kilometer in length! I guess the mole-rat I found must be an individual that has left his/her colony in search of another in which it hopes to be accepted as an immigrant.    

Another exciting discovery that took a long time to identify is the Northern Vampirecup, Cytinus visseri, which I photographed in May but only recently identified. This plant is a rare fully-fledged parasite that produces no chlorophyll at all (which is required for photosynthesis) and so relies on other plants, particularly Helichrysum reflexum of the Daisy family, for survival. That Helichrysum, which according to the literature is the only host to this plant, is a dense rounded bush of about a meter cubed which usually conceals the parasite although this individual was exposed. So it was unlikely that that was the  plant it was parasitising. The one green leaf visible in the photo resembles those of a plant in the Carrot family. Of course, if I had known I would have recorded the nearby plants but alas... Anyway H. reflexum does occur here on the Estate at high altitudes amongst rocks and it has a beautiful, rounded shape with copious amounts of pretty paper flowers. The parasite also produces no aerial vegetative structures and the only parts seen above ground are the maroon flowers which are enclosed in their petals. The petals have hinges, though, that enable the petals to fold right down at ground level exposing the flowers that contain copious amounts of sweet nectar (+30% sugar!). The plants are dioecious (male and female flowers occur on separate plants) and the exposed flower in the photograph is a male. The pollinating of the plant is also quite rare: The plant produces a scent (plasticy and yeasty to humans - not so attractive!) that is extremely attractive to small mammals like the Striped Field mouse, the Pygmy mouse, a Dormouse and the Short-snouted Elephant Shrew. These small mammals tend the flowers at night by folding the petals down and lapping up the sweet nectar and at the same time collecting pollen on their faces to deposit on the next flower and complete the cycle of pollination. This is the ONLY dioecious plant, in existence, that is pollinated by mammals! There was a study conducted between 2002 and 2006 at Mauchsberg in the Sterkspruit Nature Reserve, where the largest know population of the plant is found, close by near Long Tom where these and many other interesting facts were established about the plant and its pollinators.  

This is a photograph of a rather scraggly small tree right beside the front patio of the Miner's Cottage. But the Tree Fuschia, Halleria lucida, can grow into a handsome specimen in the right conditions. In fact, it is highly regarded as a garden subject because it is, without doubt, one of the best indigenous trees to plant when attracting birds is the motivation. Myriad Sunbird species, White-eyes, Thrushes, Robins, Pigeons, Fly-catchers, Turacos, Mousebirds and Barbets are regularly attracted when the tree is carrying flowers or fruits, which is almost all year round. In nature, they occur in stunted form on exposed rocky outcrops, on forest fringes as small trees and as large, imposing trees in evergreen forests. It also grows in disturbed places like mine diggings on the Estate. The bird-attracting, nectar-filled tubular honey suckle-like flowers are mostly concealed as they grow from the old wood of the tree. More reasons why it is a sought after garden subject is that it is easily propagated from seed, cuttings and truncheons and it is tough, frost resistant and a quick grower that thrives under varied conditions. It also usually flowers already in its second year of growth. 

Often while on a hike, somebody picks up a perfectly cubed piece of stone or points out one still embedded in a sandstone or mudstone boulder, that we call a Devil's Dice. When not in cubed form and excavated from underground and when still shiny it is called Fool's Gold because it is often mistaken for gold. The cubes we find are crystallised Pyrite ((1xFe) + (2xS) = FeS2) with a skin of Limonite where the Sulfate molecules are replaced by Oxygen and Hydrogen because of its exposure to the air. A single cell unit in the crystallised form of Pyrite is made up of 14 iron molecules and 28 sulfur molecules bonded together with an iron molecule in each corner and one in the center of each face of the cube, surrounded by sulfur molecules. A one centimeter cubed piece of crystallised Pyrite contains 1 to the power of 23 cell units, making it extremely dense. To give an idea of the enormity of that number: 1 to the power of 12 is equal to 1 trillion! As its name suggests, Pyrite, when struck with a piece of iron, creates sparks and in the 16th and 17th centuries was used in wheellock firearms to create the spark necessary for the gun to fire. In those days it was also stacked and the water leached from it boiled with iron to produce ferrous sulfate, used as a dye fixative in the textile industry and as a constituent of ink. Today it is used in medicine, horticulture, gold refining, the construction of modern dry-cell batteries and more. I ground down the face of a dice with our grinder and successfully exposed the shiny, metallic lustre of the Pyrite beneath the Limonite layer but did not manage to get it to spark when I struck it with a piece of steel. The Devil's Dice I used was small and quite awkward to hold so maybe that is why it didn't spark. 

Even though the month of July falls in the dead of winter, one can still find many striking species of flower in bloom. Like this beautiful Dicliptera clinopoda from the Acanthus family that I notice flowering each year from only one place on the Estate (although commonly found hiding among the scrub on the access road in Rivendell farm) between the wooden step bridge that crosses between SPK 7 and SPK 8 and Otter's Rest (unit 10) on the Spekboom River.

And finally, another striking flower blooming in the middle of winter, a Crimson Balloon Pea, Lessertia frutescens, After pollination, the striking, flattened pea flowers develop into a puffed-up balloon within which the seeds reside. This large bush was photographed on the river path along the Majubane river between Morrin Pools (unit 14) and M3 about 10 meters off  the western side of the path. Hard to miss in the drab winter colours...

What an exciting month for me, eh? That is such a special feature we have here on the Estate: the fact that there is always something amazing going on out there in our mountainous piece of heaven! If you stumble upon anything interesting, or anything you want to know about, photograph it and send it to me at jimmy@finsbury.co.za and I will try to identify it for you and if it is something interesting, I will incorporate it into one of my monthly blogs. So long!