Anonymous composers

[Amelia.pd]

If a piece of music is by an anonymous composer does this mean it's in the public domain? As composers usually own the copyright to their works aren't their pieces in the public domain if no one knows who they are?

What should I look for when determining the copyright status of an anonymous piece?

[Carolus]

In a word, no. A commercial jingle may have been composed only last week as a "work made for hire", with no composer attribution whatsoever, and a copyright claim by the party who paid for the work. Anonymous or not, such a work is fully protected.