Books like Tolkien Bestiary
David Day
Tolkien Bestiary is 288 pages, about 5 hours 17 minutes at 250 words a minute.
8 books to read next
How long each takes
The Return of the Shadow 9.1 h 
The Letters of J.R.R. Tolkien 9.2 h 
The War of the Ring 8.7 h 
Tolkien 5.3 h 
The Lays of Beleriand 7.2 h 
The Atlas of Middle-earth 3.9 h 
Inklings 5.3 h 
The Map of Tolkien's Middle-earth 1.2 h Bar height shows length. Estimated at 250 words a minute.