Rats are invading my property! A neighbor to one side has bird feeders everywhere and the neighbor on the other side has chickens. I have tried several rat killers (DeCon, Rat X, even an electric shock box). They just keep multiplying! There are rat holes all over my yards and gardens, they get underneath my house. What can be done to permanently eradicate them? Is there an industrial poison available?
I'm afraid there is no permanent solution. Habitat modification via better management of the food being left out on either side of you is going to be a huge part of how you experience the size and spread of the population. Wildlife management, especially with pest problems like this one, is largely a situation requiring communication and cooperation among humans. The bird-feeding neighbor can decrease spillage by adding trays to the bottoms of feeders to avoid having the "kick-out" reach the ground...and the rats. The chicken owner could limit rat access to the feed inside a coop by using hardware (1/2") cloth. Beyond working with your neighbors to manage the food they're inadvertently providing to the rats, you will want to take measures to stop the animals from using your crawlspace. You haven't mentioned whether the rats are underdigging a slab, a subwalled crawlspace, or a skirt, but essentially you need to look at your situation and rat-proof the structure. This publication http://icwdm.org/handbook/rodents/ro_b137.pdf is getting dated but still has some good tips. Snap-traps inside a box set (to avoid snapping non-target animals) could be helpful in the garden and along walls. Toxic baits for rats should be used in bait stations that again, limit access to only rat-sized and tunnel-inclined animals. Another option to consider would be contracting a licensed and trained wildlife control operator http://www.dfw.state.or.us/wildlife/license_permits_apps/wildlife_control_operator_contacts.asp
to help knock down the population in your yard with restricted-use rodenticides (have to have a license to buy) and/or help in doing the rodent-proofing on the structure.