Establish and cover your travel time rate costs out and back to the job, avg. anticipated on site time if you are doing regular trap maintenance and any material costs and you will be working on the profit side in most cases.
Whatever the reason for site visits you must always bill this to your job unless you are doing occasional courtesy visits for some reason that may be necessary or on your route of travel daily.
You start billing for animal charges only you wont do very well on average if you don't price that rate with good judgment in mind.
Extended time on any job will run you into a steady time and cost expense. You can charge a per visit fee then a per animal charge in the event you are doing multiple catches daily for a period of time.
There are several variables to consider in jobs that may require extended time vested, multiple catches and resetting multiple traps on a daily basis. Type of animals etc.
This is a sound business approach. I guess there are many ways to incorporate it. The simplest to me would seem, setup fee, mileage or per/check fee, and animal catch fee. I just do ADC trapping as a side job/hobby and normally turn down jobs that are more than a few miles out of the way. I made an exception to that this week. Got a call from a landlord who seemed desperate. Told me he was 10 minutes away. I foolishly quoted a very modest setup fee and my normal per animal fee...which is $100 for everything other than skunks or beaver (possums, groundhogs, coons....I don't do squirrels, etc).
Well it turns out to be over 20 miles and 1/2 hour each way. I ended up catching 4 critters. Had to pull this morning but cautioned him there was very possibly more. So I sold him the body grippers and he will check for the next few days before having the entry points repaired. I ended up feeling well compensated....but when I went out to do the set up, I realized that if I didn't catch anything in the 3 checks, which is always a possibility, the setup fee would not even cover the mileage.
The thing I have noticed in ADC business is that folk are usually eager to have the problem solved but often seem to think that it should be done very cheaply or free. I had a call a few weeks ago from a guy frantic because he was trying to catch a squirrel on his patio but caught a skunk instead. So I agreed to come out right away and get it and he then proceeded to beat me down on price. I did come down some but not as low as he wanted, we met in the middle. I assumed that for him it was an affordability issue. However, when I arrived on location it was an 800k house (I looked it up afterward). So....it was not an affordability issue he just didn't put the value on the service, even though he really didn't have any other option (not the type to get his fingers dirty on a skunk).