The draft of its official practices, third edition contains a requirement of human authorship:
The U.S. Copyright Office will register an original work of authorship, provided that the work was created by a human being. The copyright law only protects “the fruits of intellectual labor” that “are founded in the creative powers of the mind.” Trade-Mark Cases, 100 U.S. 82, 94 (1879). Because copyright law is limited to “original intellectual conceptions of the author,” the Office will refuse to register a claim if it determines that a human being did not create the work. Burrow-Giles Lithographic Co. v. Sarony, 111 U.S. 53, 58 (1884). The Office will not register works produced by nature, animals, or plants. Likewise, the Office cannot register a work purportedly created by divine or supernatural beings, although the Office may register a work where the application or the deposit copy(ies) state that the work was inspired by a divine spirit.
The first example given of something the U.S. Copyright Office will not register is, of course, "a photograph taken by a monkey". The others are:
• A mural painted by an elephant.
• A claim based on the appearance of actual animal skin.
• A claim based on driftwood that has been shaped and smoothed by
• A claim based on cut marks, defects, and other qualities found in
Registration with the U.S. Copyright Office is not required for copyright protection, which takes effect when a work is created. However, registration provides significant legal advantages, such as the ability to receive statutory damages in lawsuits.