Short answers, pulled from the story.
Fowling is the hunting of birds by humans, carried out for food, feathers, commercially valuable products, sport, or trophy collecting. It was practiced across Britain and beyond, taking different forms depending on the local landscape and the target species.
A punt gun was a long, small-bore muzzle-loaded cannon mounted along the centre-line of a specially designed low boat resembling a heavy wooden kayak. The fowler lay in the rear half of the boat with paddle blades strapped to his forearms and stalked a raft of ducks until within the gun's short range before firing. In winter, the same gun could be mounted on a sled and used on frozen ground.
The term fowling is perhaps better known in the Fens of Eastern England than elsewhere, where decoys were a standard feature of well-equipped landowners' estates. The practice was not confined to the Fens, however, and occurred across many regions of Britain.
In the land margins of northern Britain, fowlers collected down feathers from eider ducks without necessarily killing the birds. The down was used for eiderdowns and quilted jackets, making it a commercially valuable product harvested directly from the nest.
In the Western Isles of Scotland, fowlers took seabirds directly from their nests on coastal cliffs. This was a distinct approach from the decoy-based or punt-gun methods used in lowland England, suited to the rugged cliff landscapes of the Scottish islands.
In the Fens and other similar wetland areas, a decoy was a standard part of a well-equipped landowner's estate. It was used to lure birds and formed an integral part of organised fowling as a managed practice on private land.