The tradition of catching live birds in the Friuli Region dates back to times immemorable. Fortunately today this practise is forbidden by law. The birds were caught to eat as well as to cage them for the enjoyment of their singing. One of many bird-catching systems devised over the centuries was that of building a 'Rocul'. 'Rocul' is one of many specialized words existing in the Friulian dialect to describe bird-catching traps and implements.
The site where a 'Rocul', or 'bressane', was built, was chosen after years of observation which pinpointed where bird migratory-corridors existed. The site had to be away from existing woodland or trees, so that to the birds a Rocul would look like a natural tree grove.
A 'Rocul' would take at least five years to develop and it would preferably be placed on a gentle slope. A double circle of white-hornbeam trees, with an external perimeter of between 40 to 60 metres, would be planted. Hornbeams are very suitable for pruning and form very good hedges. The distance between the trees of the two concentrical circles was of 4,5 to 5 metres and the final height of the trees had not to exceed 2.70 to 3.00 metres.
The relationship between the width and the height of this big trap, had to do with the angle at which birds take off from the ground to get airborne. This particular relationship between width and height, forced the birds to pass through the spaces in between the circles of hornbeams and trapped them in the mist-nets which were hung between the two circles of trees.
A tower, or 'hide', built of stones, bricks and mortar was positioned at the top of the tree circle. From the second floor of this 'Cason', the bird-catcher would, at appropriate times, throw down in the middle of the circle a kind of Y-shaped racket made of a branch inter-woven with willow twigs. As the racket fell, it would cause a whistling sound resembling the air going through the primary feathers of a diving bird of pray. This would scare the small birds which would alight immediately flying between the hornbeams and being caught in the mist-nets.
The birds were attracted to the middle of the circle, which was planted with a mixture of berry-bearing bushes and trees as well as seed bearing grasses liked by various types of birds, by the singing of decoy birds, either caged or strung up. The mist-nets were comprised of three layers: two external large-mesh nets and a loose fine-mesh net sandwiched in the middle. When a bird hit the net, the bird would be trapped by the middle net as in a sack.