The author, Nancy Castillo, writes "Blue Jays go through one complete molt a year in late summer. This molt usually proceeds in an orderly fashion so that you barely notice that it's going on. But Blue Jays (as well as Northern Cardinals) often experience a complete molt of their head and maybe even their neck feathers. Nothing is wrong with the bird and the feathers will grow back."
Moreover, Volume Two of the book series is now available! Both volumes one and two are in hardcover format (as seen below) and can be purchased any place where books are sold.
Volume One: ISBN: 9780996378529:
Book Seller Info: http://bit.ly/2AFZDCz