Seekers is a children's novel series written by a team of authors under the pseudonym Erin Hunter, who also wrote the Warriors series. Seekers follows the adventures of four bear cubs: Kallik (a polar bear), Lusa (a black bear), Ujurak (a small grizzly bear who can shape-shift into any animal), and Toklo (also a grizzly bear). Led by Ujurak, the four bears search for a place where they can live in peace without human interference and harassment. The first book of the first series, The Quest Begins, was released on 27 May 2008 and was followed by five other books, ending with the last book of the first series, Spirits in the Stars, which was released on 8 February 2011. A second series of novels subtitled Return to the Wild, also six books in length, began publication with Island of Shadows, released on 7 February 2012. The series has been well received, with critics praising the realistic behavior of the characters, the world building, and the book's themes surrounding environmentalism.