Hawks do of course have memory but as I gather this bird did not get a meal out of it (you have the hen's body?) it will be in the hawk's mind an unsuccessful hunt. This bodes well for you. Hawks can be detered several ways. Trick is to find something that your chickens can also live with. Tin pie plates that can move in the breeze on a twine or rope over an area will help if your chickens will stay underneath. So this is great for a common area they free range, but many chickens will never go there after they are strung up. Try putting one in the coop down at their level first then up a bit and a bit till it's over their head before trying them in the yard. Plastic owls work too, again get one and put it in the coop at ground level for them to get used to first then start moving it around. Interestingly it helps with Owls too, and will keep away some wild birds which helps with the introduction of lice and mites.
The only way to be sure is a covered pen and no free ranging. Don't know about you but I'm not willing to go there unless I had serious losses. I know I'm going to loose a bird now and again free ranging but the health and happyness I see in a free range flock is worth it, as sad as the losses are. In 3 years on this property I have not lost one to a raptor yet and I have lots to pick from. Sadly your young pullet may have seemed easy pickings due to her size and inexperience. Also do yuo have a roo? They are the watchers and issue the warning shreek that the hens run for cover on so if you don't have one you might consider it.
The only way to be sure is a covered pen and no free ranging. Don't know about you but I'm not willing to go there unless I had serious losses. I know I'm going to loose a bird now and again free ranging but the health and happyness I see in a free range flock is worth it, as sad as the losses are. In 3 years on this property I have not lost one to a raptor yet and I have lots to pick from. Sadly your young pullet may have seemed easy pickings due to her size and inexperience. Also do yuo have a roo? They are the watchers and issue the warning shreek that the hens run for cover on so if you don't have one you might consider it.