Despite its somber moniker, how is the Mourning Warbler's song usually described?

Answer

Loud and robust

The term 'Mourning' is purely descriptive of a specific plumage feature and is not an indication of the bird's song quality, which is often characterized as loud and robust.

Despite its somber moniker, how is the Mourning Warbler's song usually described?
namebirdOriginwarbler