Condemning the Commons?

A recent study of bird numbers recorded in 25 European countries suggests that there has been a 421 million decline in totals over the last 30 years (http://news.yahoo.com/europe-421-million-fewer-birds-30-years-ago-004353783.html). Although one should, perhaps, have reservations about the absolute figures, it does seem evident that bird numbers have shown a dramatic fall over this time. The situation is, however, patchy as there have been increases in the numbers of some rarer birds such as the Wren and the Blackcap where they have been subject to conservation programmes. Simultaneously, there have been striking declines in the numbers of 'common' birds such as the House sparrow (down almost 150 million i.e. by 62%) and the Starling (down by 53%). Although bird declines have often been blamed on changing farming practises (and habitat loss), some of the decimated species are not farm-land birds. In such cases, urbanisation (or even conservation efforts directed at rarer species) may be closer to the root causes. Perhaps we shouldn't be so obsessed by real or apparent rarity?