Banty, with a mini forest nearby, yes you probably have a weasel/mink issue, also maybe a hawk too. My cats kill the mink in my forest. You need to make your coop/run predator proof, inspect and secure anything bigger than a 1/2" hole.
Early morning is prime hunting time for Great Horned owls, Barn Owls, and Snowy Owls. The Snowy Owls are in the region on the winter migration. They have been spotted on Whidbey Island just recently. Everybody's got to eat. Rodent populations are down and chicken is now on the menu.
If you keep chickens, know your predators. Supervise your flock until you can figure out how to let them free range safely and get your coop and run predator proof. If you are losing birds every few days it is a good indication your address is well known to them.
At this point, what kind of predator doesn't change the fact you are losing birds. You need to outsmart them. It can be done. It is very sad you have lost your lovely birds but now get mad! Do everything you can to protect them.