Post Mounted Grass Roosting Pocket with Roof. Natural materials help keep birds safe from predators as they blend in with surrounding areas and do not attract unwanted attention. Birds desire a house made of rough material because rough surfaces make entering and exiting easier. Reed grass and cedar roof are resistant to premature decay. Roosting pockets are especially beneficial to non-migrating songbirds during the winter months. They provide much needed refuge from harsh storms, wind, freezing rain, heavy snow and the bitter cold. Reed Grass Construction. Natural ventilation and drainage, blends into surroundings. Loved by a wide variety of songbirds.