A brush wallaby with its baby is seen at the Warsaw Zoo in Warsaw, Poland, April 9, 2021. (Str/Xinhua)

A kangaroo rests in the sun at the Warsaw Zoo in Warsaw, Poland, April 9, 2021. (Str/Xinhua)

A cheetah is seen at the Warsaw Zoo in Warsaw, Poland, April 9, 2021. (Str/Xinhua)

A parrot cleans its feathers at the Warsaw Zoo in Warsaw, Poland, April 9, 2021. (Str/Xinhua)