One of my friends is running a suppressor (silencer) bill through the House (Washington state, not US Congress) making use of suppressors legal in Washington. Right now their ownership is legal, but use is not. Washiongton is one of 38 states that allows ownership, but we are the only one that doesn't allow use. Suppressors are federally regulated under the National Firearms Act, and can be purchased through any class 3 dealer, provided you either get the local sheriff or police chief to sign off on your application and send in 2 sets of finger prints, or you can go the trust route and bypass that. I did the trust route. Then you pay a $200 TAX STAMP, and wait. Could be a few weeks, or it could be a few months.
The bill has passed all the way through the house, and has made it part way through the senate. Just a few more steps and the bill should pass. They do not make the weapon totally silent. They only reduce the noise level. A suppressed .308 is still easily heard. Same with a .22lr.
Some states manage wildlife through DNR, others through a department of fish & wildlife (DFW). Washington has both, but our DFW manages the animals. Animals in the act of predation are fair game when it comes to pets and livestock. I've been a deputy in a rural area, and we received calls about someone shooting "poor coyotes", and when we get there, there was livestock around, and there was a dead coyote in the immediate vicinity. All we would ever comment on was shot placement, shake the shooters hand, and tell them to be careful where they shot.
Electronic calls are legal for coyotes and bobcats in Washington.