Since this blog has become something of a site for closet birdwatchers, here's the link to an article in Süddeutsche Zeitung about the bird census currently conducted by the Naturschutzbund Deutschland.
This is a collective effort, so do participate. All it takes is an hour outside, watching the birds fly in and out of whatever greenery you have by you. Yes, this process may be accompanied by a glass of wine or two (or a beer, if you must). As the weather will be splendiferous at the weekend, you're bound to be catching numerous birds with one stone (pardon the pun): suntan, Vitamin D, serotonin ... and intimate data on the post-dinosaur population on whose territory you currently care to dwell.
The results can be phoned in (the number is in the article). The relevant form for your own birdwatching hour is here.