When sourcing bird trap cages, prioritize material durability and bird safety. Look for high-tensile galvanized steel or stainless steel wire to prevent rust and ensure structural integrity in outdoor environments. The mesh size must be appropriate for the target species to prevent escape or injury; for small birds, a mesh of 1cm x 1cm is standard. Additionally, ensure the trigger mechanism is highly sensitive yet robust, typically made of non-corrosive spring steel, to ensure a high capture rate without frequent maintenance.