sentences:  The zoo has undergone two major reductions, the first in 1981–1985, as a result of sewage system and motorway feeder construction, which reduced the area of the zoo to one-third, destroying two-thirds of the original exposition area and causing animal relocation within the zoo.As a consequence, a modern enclosure with the largest collection of exotic birds in Czechoslovakia had to be demolished and the birds were sent to other zoos.In 1991, a tiger escaped during the night and was shot within the zoo area.