How well does large glass or acrylic-fronted aviaries for parrots and other birds work? Is it true that parrots will know the boundaries of their glass cages within a short time? Are there any specific problems associated with glass or acrylic-fronted aviaries? And why doesn't more zoos have them? I know that Berlin Zoo have glass-fronted aviaries in their birdhouse. So I'm sure they exist.
Parrots are extremely intelligent, no doubt they can recognize the glass of their enclosures quickly. Prague zoo keep amazons in a glass-fronted enclosure and also in other part of the zoo there are lories (Chalcopsitta duivenbodei, Charmosyna papou goliathina and a Lorius) in glass fronted enclosures.
As a general rule birds do fine in them. There is generally an initial learning period where the bird gets a feel for the glass barrier, especially if it originally came from the wild or was raised in a wired aviary. Birds that are born in glass fronted or all glass enclosures seem to possess an inherent "knowledge" of glass barriers. The biggest issues with glass would be streaking and mineral buildup from food, poop, and water, which makes it more labor intensive than wire or mesh, and also requires (often daily) intrusion into the enclosure to clean the glass, which can be bad for sensitive or nesting birds. The other big one is glass strikes, especially in larger enclosures where the birds can build up speed. This doesn't happen terribly often, but sometimes when a bird is newly introduced, startled or chased it can hurdle into the glass hard enough to cause injury or death. However this can also happen with aviaries constructed of any rigid material, so its not a glass specific problem. The last real "issue" (and this is usually a non-issue) is that there is no airflow with glass, so ventilation has to be through other means if it is individual exhibits in a building. Usually it means either rooms with sufficient airflow though the ventilation system, or enclosures with wire tops. Edited to add: The biggest reason why you don't see it more often would probably have to do with cost. Wire is simply a lot cheaper than glass to order and install as a general rule. Wire enclosures can also be built and maintained with staff on site, while glass usually needs an external company to come in for any installs or repairs, which is both more time and cost intensive.
In the UK and Europe, glass fronts are normal enough, especially inside bird houses like Warsaw's. In theory birds can crash into them, but the problem with scansorial parrots is they prefer mesh to clamber on. Some animals move in three dimensions with vertical space being at least as important.
The indoor aviaries in the old Bird House and the Parrot House at Chester had glass fronts and I am not aware of any problems with them, although I think they occasionally had to board up one or two when sensitive species were attempting to nest (was it the Cuban amazons? bongorob may know). The Bird House held splendid grass parakeets and vernal hanging parrots among others. The Parrot House held a range of parrots including musk lorikeets, cockatoos and smaller macaws. Both of these houses were demolished years ago and I think all the current aviaries are wired, although there are Java sparrows in the large Komodo dragon exhibit which is glazed.
When Toronto Zoo gets new birds in free-flying areas, they tend to put tape any glass areas around the pavilion where the new birds may fly into.
