The last bobcat I executed had been raiding my Guineas. In the past, I've noticed that cats will tend to kill as often as possible, and not eat the entire carcass. Maybe they're "training" their young 'uns, but they can sure wipe out a bunch of birds in a few nights, and leave the bodies around. Yotes tend to carry their kill off. For your neighbor to have lost 40 in one week, there may be a tag team match of cats working the flock. Better get on 'em fast or he'll be out of the chicken business real quick.