"Gosh, Homer" we can imagine one naive traveller from Minnesota drawling to another, noticing the giants as the plane taxis to the terminal, "makes you wonder how big the local koalas are!"

"And, Wilma, the platypuses! They must be the size of sharks," her husband gasps.

But the gigantic kangaroos, though very realistic from a distance, are in fact sculpted kangaroos, made from corrugated iron. The biggest of them is almost three metres tall and the imaginatively-named work, Roos, is by New Zealand sculptor Jeff Thomson. Thomson, who says that in the 1980s he had eight life-size corrugated iron silhouettes of elephants stolen from City Hill (one of them has never been seen again), finished installing his kangaroos this week. Poignantly, it has happened in the very same week in which the ACT government has announced the culling of 1600 more flesh and blood kangaroos.

Canberra Airport boasts that Roos is the latest sculpture to be commissioned as part of Canberra Airport’s commitment to public art and the 14th major sculpture in the airport precinct. It consists of two males and a female with a little joey tucked away. It's located adjacent to the main runway at the north of the airfield. The beasts are lifelike from a distance, but at almost three metres high, the sculptures are vastly larger than real eastern grey kangaroos.

Thomson, speaking from New Zealand says that he's been making works (lots of them animals) for decades from recycled corrugated iron. He lives near Auckland and has what he calls a "library" (a warehouse) of sheets of corrugated iron of all colours and states of wear and tear. Canberra Airport supremo Terry Snow knew of Thomson's corrugated iron work (he may have seen the Thomson corrugated-iron dairy cattle grazing quietly on a lawn at the New Zealand High Commission in Yarralumla) and in commissioning some kangaroos for the airport insisted that they be made of that characterful material.

The airport kangaroos were made in New Zealand from New Zealand-found corrugated iron in the artist's library ("Although it may be Australian-made iron in the first place," he fancies) and when they were finished he had to detach the tails, ears and feet to make the megafauna monsters portable enough to ship to Australia. He reassembled them on site where generations of naive Homers and Wilmas will gasp at them.

Once upon a time Thomson's corrugated iron animals had to be flat silhouettes (like his stolen elephants and like the high commission's cows), but for some time now he's been equipped with a powerful contraption that can roll the sheets into curves and this has enabled the airport's kangaroos to be substantial, three-dimensional, full-bodied and realistic looking. He says the iron they're fashioned from is painted with almost 15 different tones of grey to add texture and get the look just right. The pieces of iron are moulded around a base armature and riveted into place and this lack of welding means the sculpture will not rust, enabling the sturdy roos to endure.

One very cute, apparently unplanned, unanticipated outcome of the installation is that the airport's control tower has begun to use them as markers for the controlling of taxiing aircraft. For example, a Qantas flight 123 might be asked to "hold at the kangaroos".

The kangaroos seem to have been installed somewhere where, lots of the time, they will be visible (on one side of the plane) to people on flights that have landed and that are now taxiing to the terminal several hundred metres away. They have been made so huge so that they stand out in the immensity of a great space where life-size kangaroos would be just dots on the landscape.

Thomson had been looking forward to seeing his kangaroos as he flew away from Canberra after installing them, "But I was on the wrong side of the plane!"

Talking to this Canberra journalist reminded the New Zealander of how, in about 1987, he made the coveted front page of this major metropolitan newspaper after eight of the 13 life-sized (and surely irresistibly collectible) iron silhouettes of elephants he'd installed on City Hill were stolen. Police recovered seven of the eight but the eighth has never been seen since.

Readers! Does one of you have Thomson's elephant or know of its whereabouts? If you will send Gang-gang a contemporary picture of it (this columnist's sacred journalistic obligation to protect his sources means you will never be dobbed in) it might well win us, at last, the Walkley Award we have thus far been inexplicably denied.

At the time, Thomson remembers, police told him it was likely the missing elephant was tossed into Lake Burley Griffin and promptly sunk, but we prefer to believe that it is roaming free, trumpeting with joy, in some fun-loving person's garden.