From CanadaTourism.com:
The cages have come down in the Small Aviary at Bird Kingdom at the Niagara Falls Aviary. Bird Kingdom transformed our Small Aviary into a FREE FLYING AVIARY! The Small Aviary was closed to the public for two days for the birds to adjust to their new environment. The Bird Kingdom Keepers monitored their behavior to ensure the safety of the birds. All birds adjusted very well and are now enjoying their new habitat.
Thanks to regular commentor Dan for letting us know about this!