Between 1887 and 1903, Zaunius was elected as chairman of the Birutė Society several times. However, his tenure marked periods of low activity and the society came close to being liquidated in 1903. In 1900, Zaunius and his daughter Morta were entrusted with managing the budget for the Lithuanian exposition at the world's fair in Paris. He also managed the budget of the Lithuanian newspaper "Varpas" from 1900 to 1905. Zaunius also organized a library at his farm. It sought to collect all Lithuanian publications. Some of this collection was donated to the Lithuanian Scientific Society in Vilnius, the rest was lost during World War II.