Furry little Otomys visitor

Untamed indigenous gardens have some special benefits as was revealed at a home in Beacon Bay on the 1st December 2017. An adult vlei rat, Otomys irroratus, followed a clearly marked run from its saucer-shaped nest to an open feeding area of grass. It was shortly followed by a pair of youngsters who cautiously started feeding close by.

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Ten species of the genus Otomys occur in Africa and O. irroratus is illustrated here. Photos: Kevin Cole                      

Vlei rats are wholly herbivorous and their digestive tract shows some advanced specialisation. The feeding trait is illustrated above where the  plant material was bitten off at the stem by the adult and then picked up in the mouth and grasped on either side by the paws and short 20-50 mm pieces cut off and chewed. Also noticeable is that this individual is sitting in a semi-upright position on its haunches while feeding. They are anti-social animals and tend towards isolation in adulthood.

Unlike other rat species only two or three precocial young are born at a time with their incisors slightly erupted (so as not to cause too much discomfort to the female while suckling).

Snakes and owls prey on the species  and in Beacon Bay mongooses and genets (large-spotted)  would also find them a tasty food source.

References:

The rodents of southern Africa by G De Graaff

The mammals of the southern African subregion by JD Skinner and RHN Smithers

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A ‘lynx’ that can cling to a wall …. .

A week ago a strange looking spider was observed maneuvering up a wall at home in Beacon Bay, East London. It was small in size with large spiny bristles on the legs. It responded quite quickly to human movement and moved swiftly up the wall.

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A lynx spider of the genus Oxyopes                                                                        Photo: Kevin Cole ELM

Intrigued and unable to identify the spider I contacted Astri Leroy of the Spider Club of South Africa (info@spiderclub.co.za). She quickly responded with the following reply ‘It’s a male (see the hugely modified ends to his palps, like little boxing gloves)  small lynx spider, of the family Oxyopidae, in the genus Oxyopes.  There are a number of species in this genus that are common, widespread and very difficult to separate into species from photos.  In fact as far as I can recall just under 30 different species in the genus’.

Reading up on these spiders it is further revealed that they do not build a web, are not known to be harmful to humans and are found on flowers, leaves, grasses and occasionally come indoors. The numerous spines stand out at right angles to the legs and some of the species can be very brightly coloured.

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Note the spiny bristles on the legs and ‘boxing glove’ like palps on this lynx spider                            Photo: Kevin Cole ELM

A behavioural trait of stalking and jumping at prey like a cat probably gives rise to their common name – the lynx spider. They have been known to jump 2 cm in the air to seize a passing insect in full flight.

References:

Spiders of southern Africa by Astri and John Leroy

Southern African spiders: An identification guide by Martin R. Filmer

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Bronze plaque from the Grosvenor (1782) shipwreck site

Mr Philip Vorster from Mboyti along the Wild Coast kindly donated a bronze plaque which reflects the history of the first steam engine to be used during a salvage attempt of the Grosvenor in 1887.

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The steam engine was manufactured by Robey and Company in Lincoln (UK). Mr Bryan Edwards of the Robey Trust kindly provided the following information related to the number 9987 on the plaque:

“9987 is an entry in Engine Book 2, and as such the details are more brief than they were in EB3 onwards.  All we have is that:

9987 was a 12hp, compound (would almost certainly have been a 2-cylinder) ….

Machinery Order number  4260.

Delivery:  19-10-1887″

The steam engine was landed in Durban and transported overland by wagon to the Grosvenor wreck site.

The museum has a permanent display about the Grosvenor in the maritime gallery.

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Nahoon Beach – storm surge event

Nature is proving the hypothesis that increased annual storm surges will be experienced along the South African coastline in years to come. The museum has recorded events over the past two decades and it has been noted that apart from big storm surges every few years (the last being in 2015) mini storm surges are increasing annually.

The biggest annual event occurred last night and a photographic record from Nahoon Beach illustrates just how large the impact was on the coastal primary dune adjacent to the internationally known beach.

A spring tide and days of windy coastal conditions (probably from storm centers south of the SA coast) produced heavy seas with large high energy waves displacing onto the shoreline. Areas where these waves were focused by a bay or promontory (such as Nahoon Point) received a battering and, in particular, the primary dune at Nahoon Beach.

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In recent times there has been no embryonic dune formation with concomitant stabilisation by pioneering dune plants and the effects of these waves erodes directly at the base of the primary dune. The caused massive dune slumping with tons of sand being eroded out to be deposited elsewhere.

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A hint of what was to come was noted on Monday 21st August 2017 when museum scientist Kevin Cole visited Nahoon Beach to document the beginning of an erosive coastal event. It was noted that concrete plinths used to stabilise a sewer connector pipeline had been exposed (for the first time in decades) indicating a low base erosion event along the beach.

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The dune slumping which had occurred along the primary dune at Nahoon Beach was not higher than 3m (as illustrated by the two ladies standing in the photo below taken on Monday 21st August 2017).

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The storm surge last night and this morning has further eroded the dune system, almost to the vegetation line (illustrated below- top photo Monday 21st August 2017, bottom photo Thursday 24th August 2017).

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Additional concrete plinth bases have also been exposed which run a line to the Nahoon River mouth. At the mouth on a very low tide the remains of the sewer pipe can be seen (in part) under the water crossing the river.

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As expected some other interesting specimens which have been buried will be found. A case in point is that a young visitor from KwaZulu-Natal found an animal tooth (which still has to be identified) at the Nahoon corner car park this morning.

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A site visit will be made to Nahoon tomorrow as more dune erosion is expected to take place at high tide later today and tomorrow morning.

 

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There is a dwarf in the tree ….

A few nights back an Eastern Cape Dwarf chameleon (Bradypodion ventrale) was spotted in an acacia tree in Beacon Bay, East London. Many years ago this species were quite common but they haven’t been seen regularly in recent times.

The Eastern Cape Dwarf chameleon is one of the larger of the fifteen currently recognised species of dwarf chameleons in South Africa (all of which are endemic to the country). The genus is widespread but essentially absent from the Kalahari and the Karoo.

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Eastern Cape Dwarf chameleon in Beacon Bay. Photo: Kevin Cole ELM

All dwarf chameleons are viviparous – an average of 5-15 babies are born alive and fully developed after a gestation period of about 3 months. These tiny (20mm) reptiles are fully equipped for survival and can feed on small insects.

Bradypodion ventrale illustrated above can be identified by a casque that is slightly swept back, a pale gular region and a dorsal crest composed of pronounced triangular tubercles. Two rows of larger tubercles are also noted on the flanks. It is a grey chameleon with a light central patch on the flanks. The enlarged tubercles my be yellow or green to orange-brown.

Chameleons are not found worldwide – restricted to Madagascar, Africa and some neigbouring islands such as the Comores, Mauritius, Seychelles and Zanzibar. There are about 150 – 160 species arranged into 9 genera.

Reference: Chameleons of southern Africa by Krystal Tolley and Marius Burger

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Controlled fire burn at the Beaconhurst School Nature Reserve today

Fires form part of a natural grassland ecosystem  and in areas which are protected such as the Beaconhurst School NR controlled burns are necessary to allow the rejuvenation of the grasses and the biome in general.

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Museum scientist Kevin Cole has been an honorary custodian of the reserve for the past decade and working with the principal of the school Mr Aubrey Norman it was agreed that a controlled burn should be undertaken. There was a lot of moribund grass and the combustibility of the veld in general was very high due to a persistent drought in recent months.

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The Beaconhurst School NR is an important, near pristine natural habitat in the suburb of Beacon Bay with a number of habitat types such as acacia (thorn tree) thickets, a small wetland, riparian forest (a valley of bush which joins up with the Qinira River) and the various grass types.

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Considerations for a burn which took place today included the wind speed and direction (westerly wind at 5 knots gusting to 7 knots), the anticipation of rain later in the day, preparations of  fire breaks and staff to control any fire flares (in the fire breaks which may run away into areas not included in the proposed burn footprint) and consultations with the BCMM Fire Department and the SA Police Service.

Before the fire was started Kevin spent 1.5 hours moving in transects above the riparian forest to encourage any animal specimens off the ear-marked burn footprint into the forest below. Blue duiker and bushbuck which live in the reserve were not seen in the area to be burnt. A look-out was kept for snake species and other reptiles and any such creatures were relocated to safe areas. The most difficult species to locate in thick grass are molluscs (snails) and smaller rodents.

An initial fire was started adjacent to a fire break with the wind from behind – as this flared up and raced in the intended direction Kevin moved around and started a back-burn. The process was repeated successfully until the area was burnt. There was a small break away fire which jumped the fire-break and happily the BCMM fire truck arrived timeously with enthusiastic staff to settle matters with a good dose of water.

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Kevin (EL Museum) and Andile (BCMM Fire) share a lighter moment after a smokey task at the reserve

The reserve is now ready to receive some good rains a present a flush of green in the coming months!

Beaconhurst School Chief Groundsman Stan and his staff are wholeheartedly thanked along with the principal Mr Norman for  successfully contributing to biodiversity conservation in the area.

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Risso’s dolphin stranding at Queensbury Bay, East London

Mr Alan Harris of Glen Stewart contacted the museum about a cetacean stranding on the rocks at Queensbury Bay. The animal was identified by museum scientist Kevin Cole as a Risso’s dolphin (Grampus griseus)- the largest dolphin not to be named a whale.

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Alan Harris with the Risso’s dolphin at Queensbury Bay (north of East London)

The stranding was reported on the 21st July 2017 and it it presumed (judging by the condition of the animal) that the dolphin had been floating at sea for a day or two before being washed up at Queensbury Bay. A reasonable amount of the delicate thin skin on the head had blistered off and there were a few scratch marks from a rocky entry to the shoreline.

The juvenile dolphin measured 2.01 meters in length and showed no signs of any major physical trauma. A reasonable amount of information has been gathered about Risso’s dolphins from mass strandings in South Africa between 1983 and 1991.

Diagnostic features for the identification of the species include a blunt head (beakless), a prominently centrally-placed erect dorsal fin (in adults) and numerous pale scratches and scars on mature animals. The calf stranded here is still uniformly coloured with a distinctive V-shaped crease from the blowhole to the tip of the rostrum.

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Risso’s dolphin – note the distinctive V-shaped crease in front of the bulbous head

The photo above also illustrates a whitish-grey anchor shaped mark on the chest connected by a thin mid-ventral streak with an irregular lozenge-shaped mark extending from the umbilical region to the anus. This marking persists into adulthood with the species.

Risso’s dolphins do not have teeth in the upper jaw. Erupted teeth have only been found in the lower jaw from dolphins in our waters – confined to the very front of the jaw (erupting at a body length of 1.88m). Between 2 and 6 pairs have been recorded in the species and in old animals the teeth become worn down often falling out resulting in an individual with no teeth at all.

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No teeth will be visible in the juvenile of the species as illustrated here for the stranded Risso’s dolphin at Queensbury Bay

Risso’s dolphins occur worldwide in tropical and temperate seas and can reach speeds of up to 28 km/h (normal travelling speeds are about 5.5 km/h or less). They mostly feed on squid and octopus.

Four mass strandings of the species have been recorded in South Africa – May 1983 (4 males and 4 females). April 1989 (10 males and 11 females), February 1990 (1 male and 6 females) and August 1991 (9 males and 2 females).

This is the second Risso’s dolphin record for 2017. Sean Pike of Wavecrest reported a live 1.5 meter animal which has beached close to the Nxaxo River and was released close to Sandy Point later on the same day (21st February 2017).

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A neonate 1.5m Risso’s dolphin which stranded at Wavecrest (Wild Coast) 21st February 2017. Photo credit: Sean Pike

After the release there were no reported sightings of the animal again and it is hoped it survived.

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The Wavecrest Risso’s dolphin being transported to the release site at Sandy Point. Photo credit:  Sean Pike

Risso’s dolphins can reach a length of 3.5 meters in the South African waters with the front half of the animal noticeably bulkier than the body behind the dorsal fin (whale-like upfront and dolphin-like in the tail region). At birth the dolphins are brownish-grey and becomes whiter as it ages (the combination of gradually lightening pigmentation and the accumulation of scars).

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Museum scientist Kevin Cole with the Risso’s dolphin calf which was buried after blubber, skin and muscle samples were taken. It was deemed too bloated to do a necropsy.

References:

Whales and Dolphins of the Southern African Subregion by Peter. B Best

Whales, Dolphins and Seals. A field guide to the marine mammals of the world by Hadoram Shirihai and Brett Jarrett

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