The chimney(s) in your house or building(s) should have a cap. The reasons why are many. An open chimney is exposed to rain, snow and other precipitation which can damage the inner lining of the chimney. Other contaminants and predators can also damage the chimney if they can gain access through the chimney flues.
These other potentials dangers can be insects, birds, raccoons, squirrels and more. An appropriate chimney flue cap will allow the chimney to functions and at the same time protect it.
If your chimney currently does not have a cap then it would be advantageous to consider getting one.
I invite you to read the professionally published article provided below regarding chimney caps.
Why Your Chimney Needs a Cap
Learn the importance of having a protective cover over your chimney.