Not on my watch?!

So...today I went over to check our neighbours 'chooks' and only found four in the pen when there should have been six. I didn't let them out yesterday but had done the day before but asked Will to go lock them up while I was making dinner. He didn't count them when he locked them up. What I think has happened is that when Will locked the pen door two were still outside and a fox got them in the night. One of the missing is 'Uggy', little Nate's white pekin cockeral. I found a trail of white feathers leading off into the bush behind the pen. I feel so bad that it happened on my watch.