"Australia’s average surface temperature has risen more than 1 Fahrenheit degree since 1900. During roughly the same period, the body size of Australian passerine (perching) birds has declined by as much as 3.6 percent. Zoologist Janet L. Gardner of the Australian National University in Canberra and colleagues, who detected the shrinking trend in birds, suspect the two changes are no coincidence...Within a given animal species, individuals living at high latitudes, toward a pole, are usually larger than those living nearer the equator, probably because greater body mass helps ward off the cold. In keeping with that principle, the researchers calculated that southern populations of four Aussie bird species now have body sizes typical of populations that lived 7 degrees of latitude (about 483 miles) closer to the equator before 1950. In a nutshell, smaller birds now live somewhat closer to the South Pole." - Jeffrey Marsh from Bookmarklet