This article was very true - I've actually seen this happen in my backyard (minus the hawk eating the little birds - yet!). I'll look out and suddenly there are no birds anywhere. Once I saw what I think was a kestrel sitting just over the bird feeder.
It reminded me of the woman who wrote in about the East Coast cats and how she wanted the birds and the butterflies but not the cats. Here's the thing people often forget - nature often is very cruel. For every beautiful hawk out there, there is also a little creature that has to die for it to survive.
It also makes me wonder about people who claim cats kill wildlife and therefore the cats should die. First of all, I have two cats who come over and sit right under my bird feeder - the birds pay the cats no mind, but they take off at first sight of a kestrel of hawk, which makes me think the birds know the cat isn't something to get too worried about. In addition, I've never seen the cats ever catch a bird. So why is it that people get very upset when a cat happens to kill a bird, but don't say anything when a bird kills another bird? Aren't both part of the same cycle? Both are tragic - I would hate to lose a bird to either a cat OR a bird - but you have to think that is life.