The Invisible Sharp-Shinned Hawk
From the newsletter Inbound (go ahead and subscribe now!).
Pigeons abound in North Station; South Station doesn’t have an indoor bird in sight. WGBH investigates and finds that the reason is the BIRD-X Repeller, a small speaker that randomly plays bird of prey calls, which scares away other birds. You may never see a Sharp-Shinned Hawk in South Station, if you listen, you may hear its call terrifying the pigeons away.