The game's popularity has spawned knock-off and parody games that utilize the same basic mechanics as Angry Birds . For example, Angry Turds features monkeys hurling feces and other objects at hunters who have stolen their babies.  Another game, entitled Chicks'n'Vixens and released in beta form on Windows Phone devices, replaces the birds and pigs with chickens and foxes, respectively.  The developer of Chicks'n'Vixens intended the game as a challenge to Rovio Mobile, which stated at the time that a Windows Phone port of Angry Birds would not be ready until later in 2011.  The Angry Birds theme song ( Balkan Blast Remix ) and its characters appear in Just Dance 2016 . 
A fifth episode, called "Ham 'Em High", launched on December 23, 2010, in celebration of the game's first year in the iOS App Store.   "Ham 'Em High" contained 15 American Old West-themed levels in a single chapter;  updates on February 4, 2011 and March 18, 2011 each added one new 15-level chapter.   "Ham 'Em High" also introduced the Mighty Eagle, a new bird that may be used once per hour to clear any uncompleted levels.  The Mighty Eagle can also be used in previously completed levels, without the once-per-hour limit, to play a mini-game called "Total Destruction" in which the player attempts to destroy as much of the scenery as possible, both with the standard birds and the Mighty Eagle; achieving 100% destruction earns the player a Mighty Eagle feather for the level.