sealant

I am based in Australia. I plan to build a 2 - 5 meter aviary on my verandah with my deck as base to make hosing it out easy. What can I use to seal the timber and protect it from damage by bird poop and water?

We were planning on DIYing a large cage for an Eclectus and were wondering if all we were going to be using is safe Pinewood (Know it's safe from researching) 1-inch spacing chicken mesh/wire Are there any bird safe varnishes along with bird safe sealants/polyurethane? We made plans etc. but...