“Birdhouse Group,” 1922, by National Photo Company, via Library of Congress Prints and Photographs Division (all pictures here).
I’m not certain, but I believe this happy group of young designers/builders were Washington, D.C., schoolchildren taking part in an annual “American Forestry Association National Bird House Contest.”
The Library of Congress has a set of 1921 photos labeled as such (and also as “bird house story”). You can scroll through them by clicking on any thumbnail in the gallery below.
Unfortunately, I could find almost no other information about the competition. Today, the American Forestry Association is known as American Forests. Their website does not mention the event.
The event must have continued until at least April 15, 1924, when Senator George W. Pepper made the presentation on the Capitol grounds.