It seems that this is a depiction of a variant of the profession fowler, or bird-catcher, a type of food production industry.
The bird catcher stands in an arbour camouflaged with fronds and tries to catch birds with the catching device — called Kloben — a long clamp trap that can be pulled together with a rope he holds in his left hand. Nine birds, including tits and finches, buzz above the trees. Bait seems unnecessary or optional, as it seems to rely on emulating a twig, an otherwise 'safe' and popular resting place for the birds. If one makes the mistake to land on one 'twig' the rope makes the other 'twig' move towards closing the trap and holding the feet captive.
This page in particular is described at the source Amb. 317.2° Folio 99 recto (Mendel I)
The contemporary term for it would be Kloben, a device described in more detail here:
The bird catcher stands in an arbour camouflaged with fronds and tries to catch birds with the catching device, a long clamp trap that can be pulled together with a rope he holds in his left hand. Nine birds, including tits and finches, buzz above the trees.
Or from 'Zedlers':
A Kloben is a wooden instrument used to catch all kinds of small birds, but especially tits. It consists of two long sticks, dug out lengthwise so that the height of one fits exactly into the depth of the other. Both sticks are carved a little at the bottom and then pushed into a round piece of wood prepared for this purpose by a carpenter or wood turner, whereby both parts lock together. The two parts of the block are then fitted with strong cords, with which they are pulled so tightly that they can hold even a hair. If a titmouse or another small bird comes onto such a stretched-out log, the birdcatcher pulls it closed, catches the bird by the claws and pulls it into the hut.
— Johann Heinrich Zedler: "Grosses vollständiges Universal-Lexicon aller Wissenschafften und Künste ", 1731–1754: "Kloben, ein höltzernes Instrument", ca. 1 Spalte, in Bd. 15, S. 493.
As for the practice now, I hesitate to describe that for Europe as a whole, as this
— Jodocus Oesenbry: "Vogelbuch", Thalwil, 1575 (Zürich, Ms C 22, here p40, showing a glue-stick and a Kloben).
method seems to have been popular throughout, but lost attractiveness or importance at the end of the 19th century. Today it would be a forbidden method to hunt, albeit still practised in Italy, or the Balkans, or even further east, and illegal if done on EU territory.
Especially in Switzerland, the Kloben acquired symbolic meaning, for 'catching birds' as meaning 'get a girl' or 'catch a sinner' (in Catholic lands apparently closely thought together anyway ;):
It appears that this method wasn't popular in English speaking countires at all, as a dictionary fails to provide a direct translation for Kloben and opts for the literal and cognate way to describe it as "cloven stick". (— David Dalby: "Lexicon Of The Mediaeval German Hunt. A Lexicon of Middle High German terms (1050—1500), associated with the Chase, Hunting with Bows, Falconry, Trapping and Fowling", degRuytre: Berlin, 1965. p119.)