I get that they want to make the animals feel at home (and I'm 100% supportive of that too) but at first glance that line made it seem as though that was the only effort made to make a very small space with few flamingos feel like a big space with lots of them. I realize that that is not quite the case, but I feel like deceiving the animals in terms of population numbers could end pretty badly in terms of the animals' mental state. Zoos have always made me uncomfortable....
Hm. I see how the mirror might be confusing and stressful for them, but they could also be happier with it than not -- they naturally live in enormous numbers most zoos couldn't reasonably replicate, and according to this article they can't tell the mirror from a whole lot of other flamingos. Hopefully their handlers would be able to tell if it were causing them distress.