The bears in this enclosure - now the condor aviary, adjacent to the original bridge over Flag Lane - were labelled "brown bear", Ursus arctos from about 1978 onwards. The zoo had a breeding pair of the Kamchatka sub-species Ursus arctos beringianus in the 1960s, but if memory serves, they primarily resided in the old pits near the new giant otter pool (old sea lion pool) before moving to that enclosure after it was built.
Hard to imagine that in the 1960s, the zoo's inventory of bears exceeded twenty-five in number.
The Kamchatka Bears have always confused me, the zoo classified them as U.a.collaris, a Russian subspecies. The IZYB classified them as U.a.beringianus.
I remember seeing the brown bears at Chester... well remembering my dad lift me up onto the wall to see into the enclosure. It was so sad. Did the bears simply die out, or where they helped along the way to build the condor aviary?