Wednesday 20 June 2012

A tale of african lizards


The lizards are the most diverse,abundant and visible group of the reptiles.No one visits East Africa without seeing a few lizards.Over4450 species  are known world wide.in  East Africa just under 200 species are known so far.The world’s largest lizard is the Komondo dragon Varanus Komodoensis
A monitor from south east asia that weighs upto 160 kg and may be 3.1 m in length.East Africa’s longest lizard is the Nile monitor reaching about 2.7 m or more.the smallest is the cape dwarf gecko,6 cm long (adult).There are no venomous lizards in Africa; two venomous species (gila Monster Heloderma suspectum and beaded lizard Heloderma  horridum)are found in southern North America.,

However many people in East Africa fear lizards especially chameleon ,but usually for superstitious reasons.
Lizards occupy a wide range of habitats,from the artic circle to the equator; they are nearly all terestial ,although  a few are semi-aquaitic ,and there are marine iguanas in galapago islands.In east Africa ,lizards range from montane moorlands at 3500m down to the intertidal zone where little coral-rag skink cryptoblepharis boutii hunts.Lizards are particularly numerous in the drier savanna areas od east Africa,especially where there are rocks;they tend to be rare in high altitudes forest.

In eastern and northern –eastern kenya ,there has been  a tremendous radiation of small geckoes and lacertids;no doubt there are still several un described species there.The most numerous  families in East Africa are the Geckos(55 species),the Skinks(45 species),and the chameleons (40 Species).Unlike snakes ,some lizards are social animals,living in structured colonies .Some species are commensal with man ,living in houses on on walls.

All lizards have scales,usually overlapping ,but they may be granular or juxtaposed.Most lizards have four limbs,but a few have none(so called ‘’snake –lizards’’)and some have only two.Most lizard have external ears ,snakes do not.the two halves of the lower jaw are fused,unlike those odf snakes.The tongue is not withdrawn into a sheath and unlike a snake’s tongue,is usually fleshy and undivided(except in monitors which have forked tongues).Most lizards can shed their tailif seized,and later grow a nwe one;in east Africa the only lizards that cannot do this are the monitors and chameleons.Lizards defence mechanism includes flight.camouflage and concealment ;some of the bigger species can give consinderable bite;monitors can also scratch  with their claws and lash accurately with their tail.

Lizards have many enemies in East Africa,in particular snakes,small mammalian carnivores and predatory birds.Most Lizards eat insects and other arthropods,but a few species are totally or partially herbivorous,often liking flowers or brightly coloured fruit.Most lizards lay eggs.some guard the eggs,a few species gives live birth .there are about 20 familes of lizards,of which eight occur in East Africa;they are the monitors (varanidae),geckoes (gekkonidae),agamas (Agamidae),chameleons (chamaelonidae),skinks(scincidae),typical Lizard or lacertids(lacerticidae),plated lizards and relatives (Gerrhosauridae) and girdled lizards and relatives(cordylidae).Lizards are more visible and more confiding than snakes.


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The red headed rock agama


Red headed rock agama(agama  agama)A big ,rock dweling lizard ,the males are vividly coloured,with bright orange heads and blue bodies.The head is large and triangular;males have a small crest on the nape.The eye is fairly large;and the ear opening is obvious.the body is depressed,legs strong and mascular toes long and thin . the tail is laterlly compressed ,tapering smoothly ,roughly 60% of total length.

Displaying males havea vivid red-orange or orange –yellow head;the chin may be orange or pink.the body is blue  ,often with a pale vertabal stripe that tapers posteriorly.Non displaying male look dull brown, with faint darker crossbars and green /yellow head speckles.Female and juveniles are brown , with green head speckling ,vague dark crossbars and vertebral stripe of irregular subrectangular markings;there is often a striking  bright red or orange patch where the upper limb s touch  the flank.wide speard in coastal thickets and woodland moist and dry savannah and semi desert from sea level to 2200 m altitude ,although most common below 1500 m .absent in areas without rock outcrops or big trees.

A diurnal, rock dwelling lizard, also lives on big trees, utilises buildings and walls, where dense colonies may form due to the abundance of suitable site and refuge, and lives in structured colonies with a dominant male, which will bask in a prominent spot. The female lay eggs, and mostly lays them at the start of the rainy season but may also lay to coincide with unexpected storms. The eggs are buried in a suitable hole or loose soil which are incubated about 50-60 days. 

The diet includes a wide range of insects; they are very fond of ants and may spend long hours beside ant trails, licking up the passing insects. They also take plant materials; grass, flowers and fruits .Mongoose have been seen digging up eggs clutches; the adults are often taken by small birds of pray and snakes; predation on this species by red spitting cobra has been seen in Ethiopia.


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