Fairly early on in the game, the animal screen becomes a complete mess, filling up with animals, their babies, and the random pets brought in by migrants.
Ideally, I would start an animal eugenics program, and butcher everything except a few dogs, cats, chickens, and pigs.
However, it is impossible to butcher the pets, and they continue to clutter the screen.
Is there any way to kill the pets, or manage the animals?
While you can arrange for unfortunate accidents for your pets, their deaths can be problematic for fortress morale. Another way to manage their reproduction is gelding male animals. This will control their reproduction. Birds cannot be gelded, but since they require protected nest boxes to reproduce their reproduction is much easier to control.
While you cannot cage pets, you may assign them to pastures. This will control their movements, but not their reproduction. Use both techniques and they become much more manageable.
Hopefully that helps some.
Well, to prevent the clutter it would suffice to simply assign them to a pasture, or cage them. Grazers will eventually die if given somewhere without grass or moss to eat.
You could certainly outright kill them if you prefer, but it will take some engineering. You could put them all in a pasture inside a pit or walled in enclosure, and then proceed to fill it with lava or water. I'm not certain, but I'd assume spike traps and pressure plates to trigger them would also work. Beware though, killing everyone's pets may result in tantrums and other FUN!
splinterz's version of Dwarf Therapist lets you manage animals. Gives you a big list, lets you sort by type and mark which ones get trained and butchered.
