Much has been written on the topic of camouflage in nature, and I don't have the access or the equipment to show you some of the truly marvellous examples in nature that I'm sure you've seen on the telly. However, maybe you'll enjoy some of the examples that have come my way over the years; they represent some of the most wonderful - and I use that word both advisedly and often with regard to nature - examples of evolutionary adaption imaginable.
Several approaches to camouflage are recognised. (The word incidentally comes to us straight from the French camoufler, simply 'to hide' or 'deceive'. It only appeared in English, for reasons unclear to me, during the First World War, referring to military applications.) The two most widespread in nature involve firstly breaking up outlines by use of bold and irregular patterning, and secondly blending into the background by matching colours, minimisation of shadow, and/or an overall posture and shape resembling an 'uninteresting' object.
And camouflage works remarkably well for big animals as well as small
ones; there is nothing quite like the shock of realising - preferably
from within a vehicle - that that movement is the flick of an elephant's
ear, and that it is attached to an elephant, and that there is a whole
herd all around. (Not that I can suggest why an elephant needs
camouflage!)
Context is critical. An animal which disappears into its environment is entirely conspicuous out of that context, as the following examples demonstrate.
Sumatran Tiger Panthera tigris sumatrae, Adelaide Zoo. No missing it here, but in dappled shade among grass and shrubs, it can disappear as its outline vanishes. |
Coiled among foliage, this green tree snake Thrasops batesii (Limbe Botanic Gardens, Cameroon) would not be nearly so obvious. |
Titan Stick Insect Acrophylla titan, Nowra, New South Wales south coast. Among foliage or twigs this superb monster - some 20cm long - would effectively vanish. |
For the rest of this posting I am going to focus on vertebrates; don't be too exasperated, this is merely because I have too much material for one posting, and I will make sure our invertebrate friends get their full due next time!
The examples above represent two predators and one potential prey; both roles can require camouflage, for evident and complementary reasons.
Most of the following examples employ their camouflage with the intention of not becoming someone's dinner, though in the case of the lizards and frogs for instance (and the tree snake above) they play the role of both dinner and diner in different situations.
One group of animals which needs effective camouflage comprises nocturnal birds, many of which roost in the open during the day. As such they are certainly vulnerable to direct predation, but owls in particular are also unmercifully harassed by diurnal birds, who know perfectly well that at night the owl is a very dangerous neighbour and would rather it slept and woke somewhere else entirely. Tree-roosting species have evolved some superb resemblances to tree bark, with perfect patterns of cracks and fibres.
And while looking at creatures wanting to be mistaken for lumps of tree, how about the sloths, which are permanently at risk in the canopy from large eagles?
OK, so maybe these examples aren't convincing you, though I can promise that in the right situation they are remarkable, but the ground-roosting nightjars are something altogether else! Try this one - a Standard-winged Nightjar Macrodipteryx longipennis at Ngaoundaba Ranch, central Cameroon - before looking at the clues in the caption.
Some frogs are pretty good at it too.
unidentified tree frog, Manu National Park, Peru. This a night photo, when the frog doesn't need to hide, but in the day imagine those remarkable skin patterns against a mottled tree trunk. |
Engystomops freibergii Tambopata Research Centre, southern Peruvian Amazon. This one is superb! |
Lined Earless Dragon Tympanocryptis lineata, Bladensburg NP, central Queensland. Beautifully hidden among the ochre and rust colours of its arid environment. |
unidentified agamid, north of Maroua, northern Cameroon. |
Common Gliding Dragon Draco volans, Gomantong Caves, Sabah. The matching of its pattern to the lichened tree trunk is remarkable. |
In the Neotropics there are no agamids, but there are plenty of Anolis lizards (family Anolidae or Iguanidae, depending on your taxonomic preferences). Here the priority is more likely to be towards hiding in the greenery.
Green Anole Anolis chloris, Mindo Valley, Ecuador. |
Young animals are especially in need of camouflage, especially before they are able to accompany their parents or, in the case of birds, able to fly.
Common Potoo chick Nyctibius griseus, Sacha Lodge, Ecuadorian Amazon. In this case it really isn't obvious where branch stops and chick starts! |
But even before the chicks, eggs and even nests must be hidden from predators.
Next time, I will conclude this mini-series by looking at some pretty impressive invertebrate disguises.
BACK ON TUESDAY
1 comment:
Possibly the reason the word appeared during WW1 was covered by Sir Humphrey Appleby. It was about the first time the Poms were on the same side as the French!
Martin
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