In the trash-ridden outskirts of Cairo, Egypt, precariously lofted structures rise up on stilts, home to birds that, come sunset, are set loose as the strange race begins to reroute and capture the free-flying flocks of one’s neighbors. The goal: to use flags and whistles to navigate your own birds and bring them back to their roost, all while hopefully entrapping your neighbors’ pets in the process.

Photographer Manuel Alvarez Diestro (via CityLab) flew in from London to document this bizarre phenomenon. Dating as far back as 4,000 years ago in various forms, this sport-like activity involves breeding, raising, releasing and recapturing huge collections of pigeons.

Garbage City, the informal name of the trash-collecting suburbs surrounding Cairo, plays host to many of participants, its lack of building code regular contributing to the unsteady-looking structures used to house the birds.

Not made to support heavy loads, many of these informal roosts are cobbled together from scraps and assembled like scaffolding from wood and whatever else is available.

PigeonNews gives a great deal of detail on everything from the types and ratings to behaviors of the birds and their masters, including stories of training, endurance and skill as well as sickness, predators and other mishaps.

Notably, pigeon is also eaten in the region, so while many treat it as a hobby or sport, some participants may also have other incentives for breeding (or catching) these birds.

There are as many as 2,000,000 people actively raising these birds in Egypt today, with some people spending hundreds of dollars a month on the upkeep of hundreds of birds.