Avian clutch size of increasing clutch size with increasing latitude. The proximate and ultimate causes for this pattern have been a subject of intense debate involving the ideas of group and individual selection. David Lack observed a direct relationship between latitude and avian clutch size. Birds near the equator laid approximately half as many eggs as those that resided in northern temperate habitats. He observed an increasing clutch-size from the equator towards the poles (something he referred to as the “latitude trend”) for many passerine (perching) birds, near-passerine (tree-dwelling) birds and in various other groups: Strigiformes, Falconiformes, Ciconiiformes, Laridae, Ralliformes, Galliformes, Podicipedifomes, and
Angry Birds Space easier to aim the birds. Some pigs are in space bubbles, and when the birds break them, they will freeze and smash unless they get into a gravity field. Like in "Angry Birds Rio", "Angry Birds Space" features boss fights. In February 2012, Rovio announced a new game in the "Angry Birds" series to be called "Angry Birds Space". "Angry Birds Space" launched on March 22, 2012, and features elements from the preceding "Angry Birds" games as well as new gameplay mechanics. The game initially contained 60 levels with additional levels available as free updates or with in-app purchases. For