They could be a regular type of bug, rather than a parasite. Can you post a picture? Chicken mites are usually bright red/orange or more black, and would be in the coop visible at night, or deep on a chicken's skin, not around outside. Chickens will eat a lot of bugs, anyway - when mine were chicks, they even ate ants. It may be that having this new chicken set up, you are viewing the yard more closely and so are seeing bugs for the first time that are perfectly a normal part of nature. I think as a new chicken-keeper it can be helpful to start with an attitude that things are going along in a normal way, unless you see some chicken behavior that telegraphs discomfort or pain or sickness. I would only worry about mites if I saw a chicken scratching a fair amount or looking uncomfortable, or if I viewed them on the chicken during a regular health check-over.