Is it a bird? Is it a dog? Or is it a stock standard, run-of-the-mill panther?

That's what MAF officials and wildlife experts tramped into the foothills of Mt Somers, 40km inland from Ashburton, to try to determine yesterday.

But they came home empty-handed. Not a cat, paw print or mauled sheep carcass to be found.

Yet that has not swayed local opinion. In Mt Somers village at the foot of the Southern Alps - just a dairy, one petrol bowser and a pub - this is no joke. They've known about the big black cat for years. They just didn't tell anyone.

Chad Stewart did, though. Mainly because when he drove his sheep truck into Blair Gallagher's yard last Friday and saw the big cat sitting 30m away looking at him he was "freaked".

So freaked he didn't even get out of his cab until the creature had bounded away back into the snow-covered hills.

His description - and his fear - was real enough to convince Mr Gallagher.

"He said it was about knee high with a long tail, about 90cm, and black. Yes, I do sincerely believe he saw something odd. He's got no reason to make it up. I mean, he was really quite shaken by what he saw."

Mr Gallagher was convinced enough to put up a helicopter the next morning to try to spot the animal, but overnight rain and snow had blanketed whatever footprints there might have been.

It is of course a perfect place for a stray panther to hide without ever being caught.

The Gallagher family farm is between Mt Somers and Montalto. There is still some snow on the ground but yesterday the sky was a perfect blue. Behind the farm are the foothills, then the Alps - miles and miles of inaccessible landscape.

Officials from MAF and Christchurch's Orana Wildlife Park searched the farm's borders yesterday but found nothing to suggest there is a cat or any other large animal living wild.

Their search was not based on Chad Stewart's sighting alone.

Since he reported seeing the cat Mr Gallagher has heard of several sightings of a big black cat. The first by hunters three or so years back, others as recent as three weeks ago - all within about 50km of his farm.

Panther sightings have also been reported around the country. Maf's hotline has had calls from Hawke's Bay, Auckland and the deep south of the South Island.