The Big Sit! is like a Big Day or a bird-a-thon in that the object is to tally as many bird species as can be seen or heard within 24 hours. The difference lies in the area limitation from which you may observe.
Some people have called it a “tailgate party for birders.” Find a good spot for bird watching -- preferably one with good views of a variety of habitats and lots of birds. Next, create a real or imaginary circle 17 feet in diameter and sit inside the circle for 24 hours, counting all the bird species you see or hear. That’s it. Find a spot, sit in it, have fun. Then submit your findings.
Anyone one can join! Participants are allowed to come and go from the circle -- especially for the purpose of bringing food back into the circle -- and the circle need not be occupied for the entire 24 hours.