False Bay West Coast #2: Boulderlands Blind Burrower
This cache, a 2-step short multi, is the 2nd in a 7-cache FBWC series which will take you to some possibly less well-known parts of this wonderfully wild but still easily accessible coastline – and fill a few gaps between existing caches!
The cache, a small camo-taped tablet pot, is hidden on the edge of an amazing jumble of huge boulders on this seldom visited shoreline north of Rocklands Point.
To Find the Cache:
1) if continuing from FBWC #1 (collecting the required Step 1 info en route to that cache): park at or near S 34 12.513 E 18 27.628, descend the steps, locate the signed small trail near S 34 12.525 E 18 27.659 and follow this down onto the beach. Then pick up the trail heading south along the shoreline in front of the houses and when this runs out, continue by boulder-hopping onwards past Step 1 and FBWC #1 to Step 2.
2) If doing as a one-off: park at or near S 34 12.594 E 18 27.689 and follow the small trail down and then left to the start of the boulder beach. The boulder-hop north to Step 1 to collect the required info before heading back and onwards to Step 2.
If wishing a more speedy return to your cachemobile after completing the cache, instead of retracing your steps along the shoreline, you can simply make your way up the grassy slope above the cache area to the nearby road.
Step 1: at S 34 12.554 E 18 27.696 you will see a bolt and green washer cemented into the top of a large rock. This is a high-water mark (HWM – see note below). On it you will see the number 3AB
Step 2: continue crossing the boulder beach and back onto a grassy path past the location of FBWC #1 to an area with a jumble of huge granite boulders. Make your way down from the path and through these to S 34 12.706 E 18 27.780 on the edge of a boulder where you will find another HWM metal bolt and green washer firmly attached to the rock. On this you will see the number 3CD
The cache is hidden less than 20m away at:
S 34 12.(B+C)AD E 18 27.(A+7)B(D+4)
Note: The position of a HWM is vital in identifying the seaward jurisdiction or ownership boundary of most coastal properties, the edge of many estuaries and of properties abutting tidal rivers. It is defined as ‘the highest line reached by coastal waters, but excluding that reached as a result of: (a) exceptional or abnormal floods or storms that occur no more than once in 10 years, or (b) an estuary being closed to the sea’.
All land below the HWM is public and belongs to the state. As a legal or cadastral boundary, it is recognised as ambulatory, ie. continually changing position over time. Its position at any one time is jointly determined by a professional land surveyor acting on behalf of the land owner and the Surveyor-General acting for the State and its citizens. See here for a fascinating 2021 paper Where, Exactly, is the Shoreline? and here for a well-illustrated 2012 paper on practical examples of determination of the HWM.
En route to the location – along one of the grassy areas, you will also probably have passed by one or more small mounds of sandy earth – evidence of the activities of one of the albeit common but rarely seen small mammal inhabitants.
The Cape golden mole (Chrysochloris asiatica) is a small, solitary, subterranean, insectivorous mammal in the golden moles family Chrysochloridae endemic to South Africa and found from the southernmost part of the Western Cape, to the northern region of the Northern Cape in a narrow band along the west coast.
It lives in underground tunnels, in a range of soil types ranging from sandy to moist mixed with clay. It thrives in loose, dry, sandy soils and cannot live in heavily clayed soils. It is found in sandy beaches and suitable coastal and mountainous areas. Due to habitat destruction, it is now found more frequently in urbanized areas than in the rural soils they prefer. It is common in parks, gardens and cultivated land, and readily invade lawns and golf courses on their hunt for insects.
Females are smaller than males but both appear the same with an average weight of 37-47g. Unlike most mammals but similar to birds, they have a cloaca, a common opening for both reproductive and urinary systems.
It has several highly specialized adaptations for efficient digging and living underground: a streamlined
body with short forelegs with stout claws, smooth silky fur to help moving along the burrows, webbed rear legs for shovelling soil behind, a pointed head with a leathery nose patch (shield) to facilitate burrowing, vestigial eyes (sight not needed in the dark), enhanced smell and hearing, and no external tail. They also have extremely efficient kidneys meaning they can survive with minimal water intake and produce very concentrated urine.
It has a very dense, soft, and silky coat which is coloured blackish to slaty-grey and brown to pale fawn. It has a thick undercoat and a water repellent layer of fur, which lies in the opposite direction. It has enlarged club-shaped mallei, which allows it to hear seismic vibrations. Their eyes are vestigial and furred over, just like their ears. For communication and perception, they mostly rely on their acute/enhanced senses of hearing and smell.
Very little is known about their system of mating. Pairs most likely come together as the result of long-distance calling generated as ground waves, as this is their main mode of communication. They breed year-round, particularly during summer. The have an average of 2 offspring about 4cm long, born almost hairless, and suckled until near maturity. The average lifespan of the mole is not known.
They forage on the surface or in shallow surface tunnels and can hear seismic vibrations created by their prey. They are very elusive and spend most of their time in extensive burrows and tunnels which are approx 200m long. They create up to 20m of surface tunnels daily for hunting grounds.
They enter torpor when the ambient temperature is cool, conserving energy and storing water. During this
state, their body temperature decreases and little activity occurs. They have a lower body temperature than other similar-sized mammals, averaging 32.9 C.
They are sensitive to ambient temperature changes due to their large surface-area-to-volume ratio, small amount of body fat and rapid heat exchange with the environment. As a result, they are active during the morning and at night, the cooler parts of the day. In an ideal habitat, they can be found at a density of 4/hectare. This relatively low density is due to their solitary lifestyle. They adjust fairly well to other habitats, such as developed suburbs where they can be found in gardens.
They are insectivorous, eating mostly insects and other small invertebrates, although they also eat small lizards. They typically forage on the ground surface or in tunnels at night, dawn or twilight. Ground vibrations created by their prey are detected by the mole’s hypertrophied mallei. Less commonly, they may forage on sandy beaches for isopods and amphipods, two types of crustaceans.
They are preyed on by owls and due to habitat destruction can now be found in suburbs and cities where cats and dogs may prey on them. To avoid such predation, these moles listen to ground vibrations and when detected, they know to stay away from the source.
See short videos on the CGM here and here (burrowing).