Tomcats will roam looking for a lady friend. They spray indoors and out - very odoriferous - to mark territory. They will fight with other tomcats. The resulting abscess necessitates a vet visit, antibiotics, unhappy cat, unhappy owner. Neutering is a very minor operation for tomcats. Can be done when cats reach 2 pounds. They remain calm, are loving pets, don't wander or fight or spray. (Queens can be spayed at same weight, but surgery is more complex. Queen no longer squalling for a tomcat to come visit and subsequent unwanted kittens who need a loving home.) My cats are now indoors only. When I had indoor / outdoor cats the most common prey were voles, mice, chipmunks, baby rabbits, very very rarely birds. Judy in New Jersey where weather is wobbling from chilly windy days with close to freezing nights and two days later rebounding to high 60s Fahrenheit