The anti-sparrow policy was active from 1955 to 1960, with major implementation of the campaign starting in 1958. At least 200 million sparrows were killed nationwide in 1958; some sources say about 2.11 billion sparrows died. The campaign led to surging insect populations and poor harvests, and was one of the causes of the Great Chinese Famine, which lasted from 1959 to 1961 and killed millions of people.
By the end of the Four Pests campaign, the Eurasian tree sparrow was practically extinct from China, which afterwards imported 250,000 Eurasian tree sparrows from the Soviet Union to recover its population.[39][40]
https://en.wikipedia.org/wiki/Eliminate_Sparrows_campaign
Another victory for Lysenkoism!