Friday, Sep. 24 – Sunday, Sep. 26 About the IOS 2021 Big Sit Stay put. Count birds. Raise money! After the success of the spring IOS Backyard Big Day, IOS invites you to join other birders throughout Illinois on the weekend of September 24-26 for the IOS 2021 Big Sit Competition and Fundraiser. Sign up … Continue reading IOS 2021 Big Sit Competition and Fundraiser