There was a huge argument about this exhibit in another photo, and needless to say I joined in! Not the most spacious of Polar Bear exhibits, but I'll restate one of my biggest points in its favour, that the Polar Bears have good view over their surroundings and are not surrounded by three walls. Polar Bears like to know what's happening around them.
The birdie is a female House Sparrow [Passer domesticus]. Nice shot; I understand Polar Bears are more relaxed, with less stereotyping, if they have a decent view over the surrounding landscape.