Feral pigs are environmental and agricultural pests. They cause damage to the environment through wallowing, rooting for food and selective feeding. They destroy crops and pasture, as well as habitat for indigenous plants and animals. They spread environmental weeds and could spread exotic diseases.
Brown trout has a fusiform (or spindle-like) body shape. It is silver to olive-brown andyellow in colour, with small scales and large red spots covering the body. In South African dams, this species can grow up to 75cm in length and weighover 6kg, whereas in rivers, smaller specimens are found. This fish feeds on invertebrates, insectlarvae, aerial insects and molluscs, as well as the occasional fish and frog.
The distribution of Atlantic salmon is temperature dependent. While they live in fresh water, they have blue and red spots. When they mature, they take on a silver-blue sheen. The easiest way of identifying the adults is by the black spots predominantly above thelateral line; the caudal fin is usually unspotted.
House rats are generalist omnivores and so eata wide variety of plant and animal material. They are serious pests in the natural worldnature as they eat birds and beneficialinsects, and to farmers as they eat a wide range of agricultural crops. They are vectors of many diseases, including the bacteriumYersinia pestis, an agent ofbubonic plague. Despite its alternative common name-black rat - this rodent exhibits several colour forms.
The flowerpot snake is one of the world's smallest snakes, rarely exceeding 20cm in length. Adults are small and thin, on average about6 -16cm in length. The head and tail tip look much the same, with no narrowing of the neck. It feeds on small invertebrates, mainly ant larvae and pupae. The species is the only known parthenogenetic snake, i.e. all specimens are female and reproduction is asexual.
Vermiculated sailfin catfish
The vermiculated sailfin catfish has rows of armour plating covering its body; the abdomen is almost completely covered in small plates. Colour pattern is generally dark brown with either darker spots or lighter spots (or vermiculations). The adult size can range from about 50 - 70cm. Environmental impacts ofvermiculated sailfin catfish are not fully understood, but in locations where they are introduced and abundant, their feeding behaviours and burrowing activities can cause considerable disturbance.
Perch live in schools, usually in the top 50 metres of water, and often mix with other species of fish.Redfin perch are a popular sport fish with some anglers because of their fighting qualities and taste. However, they are also voracious predators of other fish and invertebrates. They can destroy recreational fisheries in enclosed waters by stunting the growth of other fish species or eliminating them.
The goldfinch is native to Europe, North Africa, and western and central Asia. It is found in open, partially wooded lowlands and is a resident in the milder west of its range, but migrates from colder regions. It is a popular cage-bird species and has been introduced to many areas of the world.
The boa constrictor is a large snake that can reach lengths of anywhere from 0.91 - 3.96m. They generally live on their own, and do not interact with any other snakes unless they want to mate. Their bite can be painful, especially from large snakes, but is rarely dangerous to humans.They are popular within the exotic pet trade, and are bothcaptured in the wild and bred in captivity.
Brown trout have a streamlined, spindle-shaped body which is silver to olive-brown, yellow, with small scales and covered with large reddish-brown spots. In South African dams, this species can grow up to 75 cm in length and over 6 kg in weight, whereas in rivers, smaller specimens are found. This fish feeds on invertebrates, insectlarvae, flying insects, and molluscs, as well as fish and frogs.