Chimney guards have become a common sight on both domestic and commercial chimney pots.   As Bird Control measure they will usually be provided to stop pigeons or birds entering the pot.  They are also a means of preventing debris such as leaves and twigs building up inside the chimney.

Some bird-specific chimney cowls are dual-purpose.   The steel mesh wall stops pigeons or birds entering the chimney pot.   Combined with a steel ‘hat’ they also prevent rain from entering the chimney pot.

The most common type of chimney cowl, or ‘chimney balloon’, is a round or conical wire device that fits into the top of the chimney pot itself.  They will block access to the chimney for the purposes of nesting.   Such cowls also deny perching opportunities on the lip of the chimney pot itself.

Chimney cowls are marketed to stop pigeons or gulls but can be used to control most species of medium and large birds.