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
The Birds (film) as they carefully escort Melanie to the car past a mass of birds nearby. The car slowly makes its way through a landscape in which thousands of birds are ominously perching. Residents in the town of Capitola, California awoke on August 18, 1961 to find sooty shearwaters slamming into their rooftops and their streets covered with dead birds. News reports suggested domoic acid poisoning (amnesic shellfish poisoning) as the cause. According to the local "Santa Cruz Sentinel", Alfred Hitchcock requested news copy in 1961 to use as "research material for his latest thriller". At the end of the same month,