We have a couple of bluebirds and tree swallows nesting in birdhouses in our backyard. The bluebirds eggs have hatched and we've heard the babies peeping from inside the box. The tree swallows had been busy building their nest and we noticed that we hadn't seen the female around in a couple of days. I saw the male perched on our deck railing and he would fly up to the opening of the box then fly off. When Terry got home from work yesterday, I asked him to put the ladder up to the box and look inside. I had a bad feeling that something had happened to the female and unfortunately I was right. Terry found the female tree swallow dead on her nest inside the box. She had been attacked, pecked on top of the head by what we think was a house sparrow. I did some research and house sparrows are known to attack tree swallow and bluebird nests. Their MO is to trap one of the birds inside the birdhouse, then attack them and take the birdhouse for themselves. Terry told me he had noticed a sparrow coming out of the birdhouse over the weekend and I had noticed one around the box as well. It made us both sad as the nest had been built, but she hadn't laid any eggs yet. I cried as he removed the little nest. I'm sensitive that way. The male keeps coming around. I'm not sure if birds grieve or not, but he definitely knows that something has happened to his mate. I just hope our bluebird family will be alright. We didn't think we would have any tree swallows this year until today when I heard that familiar chattering sound. I looked out the back door and sure enough there were four flying around, checking out the box. As of late this afternoon a pair have been in and out of the box and we hope that they can successfully nest and brood their young. Nature can be cruel at times.