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MAR­TYN ROBIN­SON trains his sights on the peb­bles pep­per­ing our stony deserts to see what he can spy

Gardening Australia - - BACKYARD VISITORS -

Cam­ou­flage is vi­tal for many an­i­mals to sur­vive. It needs to be a fairly ac­cu­rate copy of what­ever it rep­re­sents, as get­ting the wrong tex­ture, shape or size will at­tract at­ten­tion. One dis­guise that is very hard to pull off is mim­ick­ing a peb­ble, but some Aus­tralian an­i­mals man­age this trick. The top three for me are a bird, a grasshop­per and a lizard. All live in arid zones on gib­ber plains, also called desert pave­ment, where the ground is cov­ered with shiny, iron­stone peb­bles, rang­ing from the size of a fist down to a thumb­nail.

Al­though quite vis­i­ble in this im­age (above) even the gib­ber­bird (Ash­byia loven­sis) can ‘melt into the back­ground’ as soon as it crouches mo­tion­less among the gib­bers. Males and fe­males, which are very sim­i­lar, don’t ap­pear at first glance to be good mim­ics of the gib­bers, but try to keep your eye on them in their nat­u­ral peb­bly habi­tat and they seem to van­ish.

Mean­while, the gib­ber grasshop­per (in the Acri­di­dae fam­ily) matches the lus­tre and shape of the peb­bles so well that un­less one hap­pens to hop, the chances of notic­ing it are re­mote. When dan­ger threat­ens, th­ese clever grasshop­pers have an­other cam­ou­flage trick: they curve their ab­domens to one side to present a less sym­met­ri­cal shape in a bid to match the gib­bers.

But the best of the three dis­guises has to be the tiny peb­ble dragon (Tym­pa­nocryp­tus cephalus). Like the grasshop­per, this rep­tile matches the gib­bers in colour, shape and lus­tre, but it has an ex­tra di­men­sion: its tail, which could or­di­nar­ily give it away, looks like a twist of dried grass.

Now you may won­der why th­ese three an­i­mals have evolved to look like gib­bers, given how hard it must be to re­main mo­tion­less all day. The gib­ber plains have very lit­tle veg­e­ta­tion, so any­thing hid­ing in the plants is easy for preda­tors to find. But, with gib­bers ev­ery­where, preda­tors don’t know where to start search­ing for those few gib­bers that aren’t what they seem.

Mar­tyn gar­dens mainly on Syd­ney’s North­ern Beaches

Have you found some­thing in­ter­est­ing in your gar­den? Send us a photo and Mar­tyn will ID it. Email your­say@gar­deningaus­tralia.com.au with ‘Crea­ture’ in the sub­ject line.

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