That's absolutely crazy, never heard of squirrels doing that! Hope the birds were okay? Overall, the mesh is generally still safe besides apparently rare freak cases like yours. Maybe it depends on the brand? As for the link, the article mentioned is not yet completed hence why it has not been linked to this one yet, however I hope to have that one out soon as well :)
I think this is a great article to show others how you can build a specific coop just about anywhere, out of just about anything! I love the use of non-traditional things like a truck topper, whiteboards, etc. Very creative! The "blueprints" were a helpful addition, too.
Our state has many types, but we've only seen garter snakes here. This was very informative and good to learn in case we ever encounter a more hostile/dangerous type.