The man is against the paper.He think that paper have some problems.
First of all,One-Way Glass sometimes useful,but it just likes a mirror. But birds can't understand the mirror,the sky is in the mirror and the birds will think that is real sky,the bird is in the mirror,it will think that is another bird.It also very dangerous for wild bird.
Second,Colorful Designs also have disadvantage.The weakness is that the bird will think the coloful designs is a hole,it may think about to through the h