From my experience. Several years ago, I used to get for free 10-12 barn cats, gopher gitters, groundsquirrel mollesters, rat zappers, mouse mutilators, or what else one may call them 2 times a year for pest critter control for my horse breeding ranch. I had to do this due to the VERY LARGE coyote population that just loved to snack on any feline they came accross. I haven't seen a ferrel cat in our area in 20 years where we live on our ranch. Then after several years, several bleeding hears started to work at the shelter, instituted a strict spay and neuter policy, and charge $35 adoption fee. 6 months later , when I whent to get another batch of pest controllers, there were over twice as many cats there and the fee was raised to $75. About 6 months later, the cat numbers more than doubled at the shelter ( so many cats that they were roaming all over the building and the steanch was unbearable) and the fee was now $125. Now, I like animals and will pay a fair price for one. But when the lifespan of a cat in my neck of the woods is about 6 months due to the coyotes and the mouse, rat, and ground squirrel populations at least doubled and trippled ( each in the hundreds) in that length of time , hay and grain prices have at least doubled ( I buy over 30 tons of grain and over 110 tons of alfalfa hay per year so my costs have gone through the roof). So ... 20 -24 cats per year . My cost for pest control whent from $ 0 to $ $2500- $3,000 per year. Why ? I now go to the County Ag. Extention to buy treated grain for pest control and it costs me a whopping $35 per year.