In Shakespeare's Macbeth, once Malcolm's men are at the meeting place, what do they use for camouflage?

In Shakespeare's Macbeth, Macbeth has
been complacent about the safety afforded him by the witches' predictions in Act Four.
This is the second set of predictions they have delivered to him, but this time the
witches are under orders from Hecate, Queen (or "Goddess") of the Witches, to lead
Macbeth to his doom. She says this is easy to do with mortals by providing them with a
"false sense of security." Macbeth comes away with a false security
based on the information from the witches—information
Macbeth demands of them—as if he is in control
of these evil creatures. Macbeth's ambition has truly blinded him, and he behaves
foolishly.

With the new predictions, the witches have given
Macbeth information that is misleading in that things are not as they
seem. Macbeth takes the prophecies literally,
while the witches have spoken the predictions figuratively. We see
this as Malcolm's army gathers to attack; they cut down tree branches to camouflage
themselves because they do not want Macbeth's scouts to know how many of them there
are—a strategy they hope will give them an advantage when they fight Macbeth's
army.

When the soldiers advance, Macbeth's scout reports
that it looks like the woods are moving. The original prediction
was:

Macbeth
shall never vanquish'd be until

Great Birnam wood to high
Dunsinane hill

Shall come against him.
(IV.i.103-105)

Macbeth has
assumed that the woods cannot move—it's impossible. When he hears
the report from his soldier, he is incredulous and furious. The witches have misled
Macbeth because it looks as if the woods are moving: it his
then that Macbeth realizes that he has been
tricked.