No, you haven't. I can quite categorically state this, because the dahu is a legpull. When trophy hunters went to the mountains, French and Swiss guides used to tell them that the dahu was the ultimate trophy and they fell for it. Their supposed quarry is described as something like an antelope. The legend seems to have started in the Alps and from there made its way to the Pyrenees. A dahu requires two people to catch it. Standing on a perilous ledge, it will hear the first hunter make a noise which will call it to fall off its perch. A second hunter will be down below with a bag waiting to catch it.
There are local variations of the dahu. The piterne is allegedly found in Normandy, while the tamarou is found in the Auvergne and elsewhere.