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I've been a Canberran since moving here from Adelaide on the first day of 1980. I now live in suburban Duffy with my partner Louise Maher, ABC 666 radio and on-line journalist. Among my early memories is following Sleepy Lizards (Shinglebacks) around the paddocks north of Adelaide, guarded by the faithful bull terrier. I have always been passionate about the natural world, trying to understand how it works, how the nature of Australia came to be, and sharing those understandings. My especial passions are birds, orchids and mammals. For much of my life I have been a full-time naturalist, running bush tours, writing books etc, doing consultancies, presenting a regular radio slot on local ABC, chairing a government environment advisory committee and running adult education classes. Recently I have eased back somewhat, but am still writing, teaching, doing some radio work and running overseas tours - as part of my fascination with our Gondwanan origins I've been running tours to South America for the past decade. I was awarded the Australian Plants Society Award in 2001 and the Australian Natural History Medallion in 2006, both for services to education and conservation.

Thursday, 12 October 2017

Chameleons; the fascinating ground lions

Chameleons are truly amazing lizards, but until a recent trip to Madagascar I'd had almost no contact with them. Madagascar though is the world centre of chameleondom, and you can't avoid them (in the highly unlikely case that you might want to!). The 85 species – every single one of which is endemic to the island – represent over 40% of the world chameleon total (in an area less than 0.4% of the world’s land area), and more are being described every year. 
Female Jewelled Chameleon Furcifer lateralis, Peyrieras.
(All photos in this posting were taken in Madagascar. The animals at Peyrieras were captive,
in a large aviary - or whatever is the term for the lizard equivalent -
containing natural vegetation; the rest are wild animals.)
Their name comes from Latin for ‘ground lion’, though most are arboreal; I'm at a loss to explain the 'lion' part either, though it may relate to the ornate neck decorations of some species. Chameleons all belong to one family of lizards, within the broader grouping that also includes iguanas and dragons, though they apparently separated from those at least 100 million years ago. It has been suggested that, based on the concentration of species there, they arose in Madagascar and spread, but recent detailed work shows that they most likely evolved in Africa and spread to Madagascar on two separate occasions. 
Male Panther Chameleon Furcifer pardalis crossing the road near Ankarana NP,
in the far north of Madagascar.
Like all lizards and snakes chameleons must shed their skin regularly, to expose a new, larger skin beneath.
Unlike most other vertebrates their skin does not expand as they grow.
They are characterised by gripping feet, a curious rocking gait, protruding eyes which can swivel independently, horns or crests on their head or face, a prehensile tail (in most species), an enormously extendable sticky tongue and of course the capacity to change colour.

The foot arrangement is often described as zygodactylous, but that is inaccurate as it properly refers to four toes, with the outer two opposing the inner two (as in parrots). A chameleon has five toes on each foot, flattened and bound together by skin into bundles of two and three toes, an excellent arrangement for gripping branches.  
Panther Chameleons (male above and female below), Peyrieras,
displaying their distinctive foot structure.



Chameleons have excellent vision (especially for a reptile), seeing in both violet (ie the wavelengths we see) and ultraviolet light. Upper and lower eyelids are fused, and the animal sees through a ‘pinhole’ just large enough to enable the pupil to function. They can focus on an insect up to ten metres away – the best magnification of any reptile. Their independently pivoting and swivelling eyes can allow them to focus on two objects simultaneously and have a 360 degree view of the world, but when hunting they focus together to give binocular vision. 
Oustalet's Chameleon Furcifer oustaleti, Anja Community Reserve, southern Madagascar,
watching us through its 'pinhole' eye.
This huge chameleon, arguably the world's largest (see below) lives in the arid forests of the west and south-west.

Female Panther Chameleon, Ankarana NP; her left eye is looking forward and her right
is focussed out to the side.
The 'horns' are in fact nose extensions covered in scales; mostly a feature of males, they form a key aspect of display and mate selection. 

Big Nose Chameleon Calumma nasuta, Ranomafana NP.

Northern Blue-nosed Chameleon Calumma linota, Amber Mountain NP.
Male Parson's Chameleon Calumma parsonii, Andasibe Mantadia NP.
Rhinoceros Chameleon Furcifer rhinoceratus Peyrieras.
(I am almost sure of this one, but happy to take advice to the contrary.)
Short-horned Chameleon Calumma brevicorne, Analamazaotra Lodge.
The prehensile tail is primarily used as an anchor while the animal is stepping across a gap between branches, but we also observed one hanging apparently lifeless by its tail from a wet cold tree early in the morning; by afternoon it had gone about its business.
This is the same Short-horned Chameleon as in the previous photo, first thing in the morning,
still in the torpor in which it had apparently spent the night.

Female Jewelled Chameleon, Peyrieras; presumably hanging on with tail as well, just in case!
Their tongue can be projected to more than twice the owner’s body length (in smaller species), via a complex muscular arrangement supplemented by an ‘elastic power amplifier’ based on energy stored in elastic collagen. The wet sticky tip grips prey strongly; the explosive extension of the tongue is independent of the surrounding temperature, while pulling it in again is slowed down by low temperatures. Prey mostly comprises insects, but larger species regularly take smaller lizards and even nestlings.
Panther Chameleon, Peyrieras, above and below.
The tongue strike is almost too fast to see, and I am nowhere near good enough to catch it extended!
This is the start of the strike.
And this the aftermath - the grasshopper didn't have a chance!

The colour change is often assumed to be primarily for camouflage, but display to females or rival males or threats, and temperature regulation, are at least as important in many situations. The mechanism has only been understood very recently (2015), and works by a combination of surface pigments and underlying guanine nanocrystal arrays. In relaxed mode these arrays tend to reflect shorter wavelength light (blues and greens) but when they are ‘excited’ the distance between the crystals increases and longer wavelengths (reds and yellows) are reflected. In combination with the surface pigments, which can also be dispersed variably, this can produce a surprising variety of colours and shades. 

Here is a series of individual male Panther Chameleons at Peyrieras; they were more or less in sight of each other, so it is possible they were reacting aggressively, though this is a very variable species.



All Madagascan chameleons are egg-layers, but some species elsewhere give birth to live young. 

Madagascar is home to both the smallest (Brookesia micra, less than 30mm long including tail) and the largest (either Parson’s or Oustalet’s Chameleon, both of which can be more than 650mm long) chameleon species. The tiny pygmy or leaf chameleons of Madagascar (Brookesia), and the pygmy leaf or African leaf chameleons of East Africa (Rhampholeon) spend most of their time foraging for tiny insects including ants among the leaf litter on the forest floor. There are over 30 described Brookesia species, but more are being recognised by the year - not an uncommon situation in Madagascar.
Brown Leaf Chameleon Brookesia superciliaris Ranomafana NP.

Brygoo's Leaf Chameleon Brookesia brygooi, Peyrieras.

Minute Leaf Chameleon Brookesia minima, Peyrieras.

Amber Mountain Leaf Chameleon Brookesia tuberculata.This is an immature animal, but still... The skill of the guide in finding this minute creature in the leaf
litter was amazing. I don't usually photograph animals being held, but there wasn't much choice here,
and her hand does give some idea of the scale.

Oustalet's Chameleon lives in the dry forests of the south-west and west, while Parson's is from the eastern rainforests. It is generally agreed that Parson's (which can be nearly 70cm long and weigh three quarters of a kilogram) is the more massive, while Oustalet's is a little longer but more lightly built.
Male Oustalet's Chameleon Lac Alarobia, Antananarivo.
It's a tough gig being a chameleon, it would seem!

Female Oustalet's crossing the road near Ankarana NP.
Male Parson's Chameleon, Andasibe Mantadia NP.
One huge problem in Madagascar is widespread habitat loss, with little original vegetation left outside reserves; this is especially true of the vast central plateau. Populations of many species are restricted to isolated reserves, and it is often unclear if they always had such limited distributions. The tiny Amber Mountain Leaf Chameleon above lives now only on this wonderful rainforested mountain in the far north, as does this species.
Amber Mountain Chameleon Calumma amber, Amber Mountain NP.
I think that chameleons are just wonderful, and I hope you do too. I hope too that eventually I can see some in other parts of the world.
NEXT POSTING MONDAY 23 OCTOBER
In a couple of days I'll be in South America, but I've prepared three
postings to appear while I'm away, albeit a bit less frequently than usual.
My aim will be to introduce just one member of (nearly) every Australian
bird family over those three postings, beginning on the first day of
National Bird Week.
(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.)