Angryverse/Pig Days

Pig Days is a special bonus episode that acts as an Advent Calendar in Angry Birds Seasons, which would showcase a particular event in real-life as a level. It was released on July 3, 2014 in conjunction with the South Hamerica update.

Chapter 1 (2014)

 * Sun. 20 July 2014: 45th Anniversary of the Apollo 11 moon landing (1969)
 * Thu. 24 July: Opening of the San Diego International Comic-Con Convention
 * Mon. 28 July: 4th Anniversary of the creation of AngryBirdsNest (2010)
 * Sat. 9 August: 841st Anniversary of the groundbreaking of the Leaning Tower of Pisa (1173)
 * Wed. 13 August: International Left-Handers Day (1976)
 * Tue. 19 August: National Aviation Day (1939)
 * Sat. 30 August: Bacon Day (2004)
 * Sat. 6 September: NBA Finals (2014)
 * Tue. 9 September: Moon Festival (Shang dynasty, 1600–1046 BCE)
 * Fri. 12 September: Video Game Day (?) 
 * Fri. 19 September: Talk Like a Pirate Day (1995) 
 * Mon. 22 September: Hobbit Day (1978)
 * Mon. 29 September: International Coffee Day (20th century)
 * Fri. 10 October: World Egg Day (1996)
 * Mon. 13 October: Columbus Day (1492)

Chapter 2 (2014-2015)

 * Wed. 15 October: Learn to Code Day (2012)
 * Fri. 31 October: All Hallows' Eve, or Halloween (1556-1745)
 * Sat. 1 November: All Hallows' Day (circa 5th century AD) 
 * Sun. 2 November: Day of the Dead/Dia de Muertos (circa 1000 BC)
 * Wed. 5 November: Guy Fawkes Night (1605)
 * Tue. 11 November: Ahtisaari Days (unknown, commemorates President Martii Ahtisaari)
 * Tue. 18 November: William Tell Day (1307)
 * Fri. 21 November: World Hot Air Balloon Day (2004)
 * Thu. 27 November: Thanksgiving (1620s-1630s)
 * Thu. 11 December: Bird-day (5th Anniversary of Angry Birds) (2009)
 * Wed. 31 December 2014: New Year's Eve (2015)
 * Fri. 2 January 2015: Sci-Fi Day (1920)
 * Tue. 13 January: Rubber Duck Day (1970)
 * Mon. 19 January: Popcorn Day (?)
 * Wed. 28 January: Data Privacy Day (2007)
 * Tue. 3 February: Windmill Day (?)

Chapter 3 (2015)
* This was not the date of the start of the California Gold Rush. That was the date gold was first found in California, in 1842. In fact, the gold rush started in 1848 - i.e. six years later.
 * Sat. 14 February: Valentine's Day (269)
 * Mon. 16 February: Opening of the 2015 Rio Open (2015)
 * Thu. 19 February: Chinese New Year, Year of the Goat (?)
 * Fri. 27 February: Polar Bear Day (?)
 * Tue. 3 March: Centennial of NASA (1915)
 * Mon. 9 March: Anniversary of the California Gold Rush*
 * Tue. 17 March: Submarine Day (1898)
 * Fri. 27 March: Hanami (Cherry Blossom festival) (Nara period 710-794)
 * Fri. 3 April: Easter (30 A.D.)
 * Sun. 12 April: Yuri's Night (first flight into space) (1961)
 * Wed. 22 April: Earth Day (1970)
 * Fri. 1 May: May Day (?)
 * Tue. 5 May: Cinco de Mayo (1862)
 * Wed. 13 May: Leprechaun Day (?)
 * Fri. 22 May: World Goth Day (2009)
 * Fri. 29 May: End of the Middle Ages (15th century)
 * Thu. 8 June: World Ocean Day (1992)
 * Fri. 12 June: World Magic Day (1927)
 * Fri. 19 June: Midsummer's Eve (1st century)
 * Thu. 2 July: UFO Day (1947)
 * Tue. 14 July: Pandemonium Day (?)

Chapter 4 (2015)

 * Mon. 20 July: 1st Anniversary of Pig Days (2014)
 * Thu. 30 July: Release of Angry Birds 2 (2015)
 * Sun. 2 August: World Friendship Day (1958)
 * Sat. 8 August: World Cat Day (2002)
 * Tue. 11 August: Play in the Sand Day (?)
 * Sun. 23 August: Ride the Wind Day (?)
 * Sun. 30 August: International Bat Night (?)
 * Tue. 8 September: International Literacy Day (1967)
 * Thu. 16. September: Preservation of the Ozone Layer Day (1995)
 * Tue. 22. September: Car-Free Day (the 1990s)

Chapter 5 (2015-2016)

 * Thu. 22. October: 5th Anniversary of Angry Birds Seasons (2010)
 * Thu. 29. October: World Internet Day (2005)
 * Mon. 02. November: All Souls' Day (circa 4th century)
 * Wen. 11. November: Origami Day (?)
 * Tue. 17. November: Meteor Shower Day (first recorded 902 - Leonids)
 * Tue. 31. December 2015: New Year's Day (2016)
 * Sun. 10. January 2016: Crossing the Rubicon Day (49 BC)
 * Wen. 20. January: Penguin Awareness Day (?)
 * Mon. 08. February: Chinese New Year, Year of the Monkey (?)

Chapter 6 (2016)

 * Sun. 14. February: Valentine's Day 2016
 * Sun. 28. February: World Polar Bear Day 2016
 * Wen. 02. March: World Wildlife Day (2013)
 * Mon. 07. March: Women's Day (1909)
 * Tue. 08/09. March: Solar Eclipse (2016)
 * Fri. 18. March: Earth Hour (2007)
 * Sat. 26. March: Easter 2016

Chapter 7 (2016)

 * Fri. 01. April : April Fools Day, spoofed as International Pig Acceptance and Appreciation Day (1392)
 * Sun. 10. April: Golf Day (?)
 * Tue. 12. April: First Spaceflight 2016
 * Thu. 21. April: Loch Ness Monster Day (1802) (The Loch Ness Monster Terence Bird Wear could be bought on the day of the Level's release)
 * Sun. 24. April: World Penguin Day (April 25th)
 * Sun. 08. May: Mother's Day (1908) (The Mother Matilda Bird Wear could be bought on the day of the Level's release)
 * Thu. 12. May: Anger Management (promotion for The Angry Birds Movie, 2016) 
 * Fri. 13. May: Pigs Arrive (promotion for The Angry Birds Movie - the day of most international releases, 2016)
 * Fri. 20. May: The Eagle's Den (promotion for The Angry Birds Movie - China, United States, Canada releases, 2016)
 * Sun. 29. May: Everest Day - first ascent of Mount Everest by Tenzing Norgay and Sir Edmund Hillary (1953)
 * Wen. 01. June: World Milk Day (2001)