Darwin's Finches - Not Going Anywhere

Darwin's Finches. We've all heard of the birds of subfamily Geospinozae, renowned for being the catalysts that galvanized Darwin's brilliant mind into connecting the dots and formulating the Theory of Evolution. But were these birds worthy examples of evolution? While it remains uncontested that the fifteen-odd types of finches found by Darwin have different shapes of beaks (and are incidentally not related to true finches), a 30-plus year study seems to show that evolution is not really taking place on the Galapagos Islands.

Large ground finch, Medium ground finch, Small tree finch, Green warbler-finch

Peter and Rosemary Grant are a persistent and dedicated couple who've been regularly visiting the Galapagos Islands for six months every year to check on the weight of the birds, their diet, their locations, their beak size, and the weather (http://en.wikipedia.org/wiki/Peter_and_Rosemary_Grant). They discovered a frankly fascinating thing - the beak shape of the birds wasn't a continuous evolutionary progression, like it should have been for true Evolution to take place. However, what we've seen is, frankly speaking, a circle. The PBS paper on the couple says, "The Grants found that the offspring of the birds that survived the 1977 drought tended to be larger, with bigger beaks. So the adaptation to a changed environment led to a larger-beaked finch population in the following generation...as the Grants later found, unusually rainy weather in 1984-85 resulted in more small, soft seeds on the menu and fewer of the large, tough ones. Sure enough, the birds best adapted to eat those seeds because of their smaller beaks were the ones that survived and produced the most offspring." (http://www.pbs.org/wgbh/evolution/library/01/6/l_016_01.html)

The graph fails to show the 1984-85 shift of beak depth that occurred later, bringing the beak size back to the median

Does this seem rather odd to anyone? I mean, evolution is all about going forward, changing from a shrew to a higher mammal and such, and here we have an article in PBS saying proudly in the conclusion that "evolution has reversed itself". And that too, in regard to Darwin's finches - one of the most widely accepted Icons of Evolution to be found! What we've seen instead is behavior uncannily similar to that predicted by creationists - that kind reproduces with kind, and that those kinds stay distinct from one another.