Lost two pullets this week- What am I dealing with?

[FromChictoChick]

My birds free range in our suburban MA yard. There is a 5' chain link fence surrounding the entire yard and there are bushes, shrubs, etc along the perimeter.

Two juvenile pullets were being introduced to the flock of young mature hens, but I lost one on Tuesday and one on Saturday, both around the time I went to close up the coop and hen house.

Here's what I know, both happened the same way:
Dusk/early evening
Pullets were taken to the back of the yard, but not out of the yard
Found lots of feathers, the head and the intestines, plus the croup- nothing else

What am I looking for? And how can I let them free range, but keep them safe??

 

[Comeonbroodyhen]

I would set a trap and bait it with some scrap meat from the fridge then you won't have to keep guessing

 

[FromChictoChick]

I'm wondering if it isn't an owl though and I'm hesitant to draw something into the yard as my dogs also go out in the yard (though not alone or at night)

 

[Vinegaroon]

Lots of hawks in new territory for the winter. If you're finding the remains at dusk when you run 'em into the coop i don't think it's a nocturnal predator. Somebody is finishing there meal by the light of day.

 

[FromChictoChick]

it's definetly right after dark