If you are unfamiliar with wire guage, the lower guages are thicker wire. Higher guage is thinner wire.
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Chicken wire is typically around 20 guage. Heavy-duty fencing used to contain horses and goats is usually around 10 guage.
Macaws can snip through most fencing like it isn't even there. Heavier stuff might slow 'em down, but if they are being left unattended in the enclosure all day ... they have plenty of time to work on it.
Many pictures you will see of macaw aviaries on-line are actually for "play areas" or exercise pens. They are not intended to contain the macaw all year round - just for a few hours each day under direct supervision ... because the birds could cut their way out in fifteen minutes, if they got bored and wanted out.
This doesn't mean you can't contain a macaw using wire mesh, but you definitely need to give serious consideration to the quality (and thickness) of your materials. The gold standard for parrot aviaries is stainless steel mesh. For macaws, heavy duty stainless steel rope mesh is ideal.
Something like this:
Parrots enclosure wire rope mesh is easy to install and maintain, and it has a long service life to create a neat space for parrots in zoo.
www.zoo-mesh.com
Also, be sure to avoid using galvanized metal in your construction. The zinc coating is toxic to birds.