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Saturday, March 16, 2013

Snouted Cobra, Naja annulifera


Snouted Cobra, Naja annulifera

This snake was found in the Waterberg Mountain range. They are a relatively widespread South African species which favour bushveld ecosystems. 

This individual has a mixture of markings common in this species, namely banded and plain phase. The banding can be seen near the tail.



The distribution within South Africa is shown in the following map accessed at http://sarca.adu.org.za/ :



This particular individual was found on a warm night. It was foraging and when approached it put on an impressive display. Hissing, striking with an open mouth and also made a mock charge – as soon as the snake was touched with the hook stick it immediately dropped and tried to make it’s escape. 





The venom of this species is potently neurotoxic and any bites should be regarded as a medical emergency.

Proliferation of Specific Birds and Animals in the Johannesburg Area



Johannesburg’s environment has changed substantially from a Moist Highveld Grassland Biome into an ‘Urban Forest’ made up of roughly ten million trees.[1] To get an idea of what the terrain in Johannesburg must have looked like in the past one could look at the Melville Koppies Nature Reserve in Central Johannesburg and Klipriviersberg Nature Reserve in the South of Johannesburg. The rapid urbanisation of the Johannesburg Area: through development of pristine grassland and the draining of wetland areas into office parks, strip malls, housing complexes and the urban sprawl and associated human activities has led to a high number of local extinctions.
            


Humans are destructive, but human activity has led to certain environmental conditions that have opened up spaces for the proliferation of a few species that are able to find a place for themselves in our rapidly changing urban environments. In Johannesburg, the creation of an urban forest has enabled a few opportunistic animals a chance to establish themselves in a new environment free from established competition and to a large degree, predators.[2] Some of these are new arrivals from other regions and others have always been here but have become more common due to some ecological factor or another. Birds are among the most successful of these animals and are for many people living in the urban forest that is Johannesburg the only real source of wildlife they may encounter.
 
Traditionally there are certain types of birds that are associated with humans. These include the cosmopolitan city bird, the Rock Dove or Feral Pigeon (Columba livia). This is an introduced species and is abundant even in the most densely populated areas in Johannesburg. There are another two pigeons in the area, although not as common as the Feral Pigeon, that have become well established in the urban environment, these are the Rock or Speckled Pigeon (Columba guinea) and the African Olive or Rameron Pigeon (Columba arquatrix). In nature the Speckled Pigeon favours roosting on cliffs, large boulders and even caves, in Johannesburg it can commonly be found roosting on buildings in suburbs and urban areas. This pigeon is very striking with its brick red colouration and quite undisturbed by people. The African Olive Pigeon is a forest species and was not always a bird of the Johannesburg area. In some areas populations are suffering due to deforestation, but in Johannesburg their numbers are steadily increasing. These pigeons are fruit eaters and are significant distributors of seed and they play an important role in the urban forest. Another bird that has a long association with humans is the House Sparrow (Passer domesticus). This bird, like the Feral Pigeon is an introduced species from Europe. It was first introduced to Durban in the late 1800s and there were separate introductions to East London and Maputo. It became established in Johannesburg by 1949.[3] Even though the House Sparrow is non-native it is not a threat to native species, unlike another introduced species: the infamous Indian or Common Mynah (Acridotheres tristis). This species was introduced to Durban in the early 1900s from India, central and southern Asia and were first introduced in Johannesburg in 1938.[4] They are now locally abundant. These birds are aggressive, bold and intelligent and they are undisturbed by traffic and people. They seem to have displaced local species, like the Pied Starling (Spreo bicolor), but field observations have shown a recent trend toward an increase in indigenous starlings in the Johannesburg area.[5] 

African Olive Pigeon

Another introduced species in Johannesburg is the Rose-ringed Parakeet, the population seems to have originated from aviary escapes. These green birds are the only parrot species that occur in the greater Johannesburg region and can often be seen in the more forested areas, their green colour and long tails make them unmistakable. They are very noisy birds and highly gregarious.

Rose-ringed Parakeet


In urban and suburban areas, where there are gardens, there are lawns. Lawns are also commonly cultivated on the verges of suburban streets and schools, parks, sports-fields, graveyards and open areas in office parks and housing estates all make use of lawn. These cultivated lawns are good habitats for small invertebrates, both on the surface as well as below the surface. One of the most familiar birds one could find on practically any stretch of lawn or any piece of open ground with grass is the Hadeda Ibis (Bostrychia hagedash). 

Hadeda Ibis

These large birds are common throughout the Johannesburg region and their call is as familiar in the suburbs as car alarms and dogs barking. Increasing lawns as well as an increase of trees in the region for roosting has led to this species continued success. Open lawned spaces have provided a habitat for lapwings or plovers (Vanellus) of which there are three species which are most often seen in Johannesburg, these are: Crowned Lapwing (V. coronatus), Blacksmith Lapwing (V. armatus) and the lesser seen African Wattled Lapwing (V. senagallus). These birds commonly mob humans and animals that stray too close to their nests, which are built on the ground. If the mobbing does not work and the threat becomes too close to the nest or young, one of the birds will pretend to be injured and attempt to lure the threat away. The young plovers are excellently camouflaged and I have seen them seem to vanish before my eyes. All three of these species have become more common in Johannesburg due to human land use. The Spotted Dikkop or Thick-knee (Burhinus capensis) is another bird that is expanding its range in the suburbs. These birds are nocturnal and can often be seen at night on suburban verges. They look like big plovers and have long legs with which they run down their prey. In the day they can be seen crouching or standing amongst vegetation and tend to stare out eerily. There are two owls common in the Johannesburg region and these birds take advantage of the bounty of rodents that are associated with humans (Rattus rattus and Mus musculus); these are the Barn Owl (Tito alba) and Spotted Eagle-Owl (Bubo africanus). Both can be heard at night in suburban areas throughout Johannesburg, the Barn Owl has a characteristic shriek and the Spotted Eagle-Owl hoots.

The urban forest has attracted some traditionally woodland birds that would not exist in the numbers they currently do if it was not for the trees and the shelter and food they provide. When growing up in the South of Johannesburg I clearly remember a period where there were simply no Grey Louries (Corythaixoides concolor). Before the 1970s they were rare vagrants to the Witwatersrand area and seem to have moved into region following a major drought in 1978.[6]  In the mid nineties I began to notice their appearance in the Southern Suburbs and now they are a very common sight. These birds have adapted well to the suburban environment. 

Burchell’s Coucal 

As the vegetation mass increases in suburban gardens the habitat of the Burchell’s Coucal (Centropus burchellii) increases. This bird is more often heard than seen and is well known for its bubbling call. It is a voracious predator and eats small mammals, small birds and nestlings, insects, reptiles and amphibians. The bird often goes undetected as it clambers through the undergrowth searching for food. The cackling Red-billed Wood-Hoopoe (Phoeniculus purpureus), although it has always been a bird of the area, is also becoming more and more common in the urban forest of Johannesburg. These highly gregarious and noisy birds move from tree to tree hunting for insects and can often be seen on thatched roofs probing for invertebrates with their long bills.

The suburban and urban environment attracts a large number of African Pied Crows, these can be seen patrolling just about any area in the region and are commonly associated with human settlements. These birds are opportunistic and intelligent, they have been known to forage under streetlights before dawn and after sunset.[7]

 

There are also some other animals that have become more prolific in the Johannesburg area and some introduced species. These include a number of insects, mammals, fish and reptiles. Some of these animals are introduced into the environment for some or other reason, some are escapees, some have just turned up and some are stowaways.[8] Others still have either always been in the area and have become more common because of human activity. This is an area that needs more (specialist) research. 

Among reptiles, there is a species of Terrapin from North America that has become established in ponds, vlies and streams in Johannesburg.[9] These used to be sold as pets and were released when they became too large for their enclosures. There is also a species of gecko that has colonized Johannesburg known as Moreau’s Tropical House Gecko (Hemidactylus mabouia). These geckos arrive as stowaways amongst holiday makers’ belongings who have been at the coast. They have managed to make use of the microhabitats that surround security lights in suburban and urban areas, the warmth from these lights and the creatures that they attract have enables this gecko to colonize areas that would otherwise be too cold for them to survive.[10] In Norwood during 2010 I found two Cape Dwarf Chameleons, one dead one and on live specimen. I am not sure if these isolated findings qualify as an introduced species, but I intend on looking for more in the area soon. The Cape Dwarf Gecko is another recent colonist to suburban and urban gardens. These geckos are active in the day and can often be seen scuttling about on tree trunks. The Striped Skink (Trachylepis striata) is a reptile that has always occurred in the Johannesburg but it is managing to survive where most reptiles are regionally extinct. This species is very common on paved areas and around houses. 

Most larger mammals are unable to coexist with humans in Johannesburg. There are some hares that can be found in park areas, on the outskirts of the city there are mongooses and even porcupines that occasionally venture in the suburbs. One mammal that is managing to coexist with humans in the suburban environment is the Rock Hyrax or Dassie (Procavia capensis). In June 2012 Municipal spokesperson Nthatisi Modingoane declared that the Dassie population is “way above the carrying capacity of the municipal nature reserves and other natural open spaces within the city”.[11] Something interesting I have observed about the Hyraxs is that they are traditionally regarded as a diurnal species, but I have observed them at night and often hear their cries late into the night. This makes me think that perhaps they are changing their behaviour due to human pressures and are foraging at night. 



 Some animals appear out of nowhere. During April 2012 there was a sighting of a Baboon (Papio ursinus) in the Klipriviersberg Nature Reserve. The Baboon was later spotted in Bassonia and Meyersdal and has since disappeared. 

The Parktown Prawn (Libanasidus vittatus) is the final creature that will be described here. Irrationally feared in Johannesburg and subject of many urban myths, from exaggerations about the impossibility of killing them, to stories about how they are the result of science experiments gone wrong. This large insect is common in the well-wooded suburbs of Johannesburg. They are carnivorous and spend most of their time underground and their biology is not very well understood. The males have spectacular heads with what appear to be tusks. There is some speculation as to how they came to be so prolific in Johannesburg. They were not reported before 1960 and then suddenly they became highly prominent, the species has been becoming more and more widespread in the region.[12] “The natural habitat for this genus is in and around forests in Mpumalanga, Northern Province and probably also Zimbabwe. During the day they can be found in burrows or under logs. Specimens have also been collected in gardens in Johannesburg, Randburg and Pretoria”.[13]

This overview of prolific animal species in Johannesburg is by no means complete. I see  this overview as the first step towards further research in suburban and urban ecology in Johannesburg.


[1] Davie, L. 2004. Jozi's urban forest now at 10m trees, and growing. [Online] Available: http://www.joburgnews.co.za/2004/sep/sep8_forest.stm [17 September 2012].
[2] Domestic cats are the main predators of the urban environment and manage to kill a lot of the slower birds that feed on the ground and smaller mammals and reptiles.
[3] Hockey, P.A.R, Dean W.R.J, Ryan, P.J. (eds). 2005. Roberts – Birds of Southern Africa, VII ed. The Trustees of the John Voelcker Bird Fund, Cape Town. (Page 1083)
[4] Hockey, P.A.R, Dean W.R.J, Ryan, P.J. (eds). 2005. Roberts – Birds of Southern Africa, VII ed. The Trustees of the John Voelcker Bird Fund, Cape Town. (Page 972)
[5] This is based on personal observation. The indigenous starlings I am referring to here are: the Pied Starling mentioned in the text, the Cape Glossy Starling (Lamprotornis nitens) and to a lesser extent the Red-winged Starling (Onychagnathus morio).
[6] Hockey, P.A.R, Dean W.R.J, Ryan, P.J. (eds). 2005. Roberts – Birds of Southern Africa, VII ed. The Trustees of the John Voelcker Bird Fund, Cape Town. (Page 250)
[7] Hockey, P.A.R, Dean W.R.J, Ryan, P.J. (eds). 2005. Roberts – Birds of Southern Africa, VII ed. The Trustees of the John Voelcker Bird Fund, Cape Town. (Page 723)
[8] There was recently an incident at Monte Casino where a Black Mamba (Dendroaspis polylepsis) was seen via cctv surveillance emerging from the bonnet of a car that was parked. The snake was caught and positively identified as a Black Mamba which is not a snake that occurs in Johannesburg. At least another two suspected stowaway Black Mambas have been caught in Johannesburg by reptile removal people.
[9] Branch, B. 1998. Field Guide to Snakes and other Reptiles of Southern Africa. Struik Publishers, Cape Town. (Page 36)
[10] Alexander, G, and Marais, J. 2007. A Guide to the Reptiles of Southern Africa. Struik Publishers, Cape Town. (Page 300)
[11] Modingoane said the City had received a barrage of complaints from residents in Fourways Gardens, Norscot and Lonehill in the north, and Glenvista, Mondeor and Klipriviersberg in the south about damage to their properties caused by dassies… Current indications suggest that while some of the dassies venture into residential areas merely to forage for food, other groups have taken up permanent residence within residential areas, sometimes in drains or roofs, or even in houses. He explained that the growth in infrastructure had led to a loss of natural open spaces, while land use regulations had resulted in residential properties “encroaching on the natural habitats of some mammal species, resulting in human-wildlife conflict.”’
waka’Ngobeni, M. L. 2012. Dassie numbers to be controlled. [Online] Available: http://www.jhbcityparks.com/index.php?option=com_content&view=article&id=838:dassie-numbers-to-be-controlled&catid=1:latest&Itemid=56 [18 September 2012]. 
[12] “The first museum specimen from Johannesburg was collected by R. du Preez in November 1962. It now seems possible that they were originally present in low numbers and that environmental changes in suburban gardens led to an increase in numbers and range. However, urbanization may not have been the only reason for an increase in numbers, and changes in weather patterns may also have played a role. When the rainfall increased over the past three summers it was expected that this would lead to a massive increase in populations, but surprisingly, the opposite occurred. It is thought that flooding of burrows and refuges could have led to a decline in populations. Unfortunately entomologists do not have quantitative data associated with changes in population density, but it is possible that this species could act as environmental indicators” Toms, R. 2003. The monstrous cricket "turns 200" while "badboy"  Parktown prawn steals the limelight. [Online] Available: http://www.scienceinafrica.co.za/2003/november/monster.htm [17 September 2012].
[13] Toms, R. 2003. The monstrous cricket "turns 200" while "badboy"  Parktown prawn steals the limelight. [Online] Available: http://www.scienceinafrica.co.za/2003/november/monster.htm [17 September 2012].