Some sit individually in trees while are clustered in sets, branching out like leaves on a building facade or hung like ivy off the sides of structures, but all of these diverse birdhouses share something in common: a single creative mind that has been working on them for years.

Street artist and designer Thomas Dambo’s Happy City Birds project is an ongoing ode to both cities and their avian inhabitants. He specializes in recycled artworks for humans as well as animals, ranging from small interventions like these to huge climbable sculptures.

Started in 2006, “the idea for Happy City Birds sprung from Thomas being a former graffiti artist, and was looking for a way to do street art in a positive way, that everyone can understand.” As with his other projects, these “birdhouses are made from recycled materials and scrap wood.”

His artist statements, like his kid-friendly creations, are not without a sense of childlike wonder and good humor. “One day Thomas felt that he wanted to know how it was to be a bird, so he built a giant birdhouse that he could hang out in. The house he build solely using recycled materials and put it up near Dronning Louises bridge in Copenhagen.”

A lot of these birdhouses are located in Arken, Denmark but they are also spread across other cities including Copenhagen, Aarhus, Odense, Horsens, Beirut and Berlin.