Why wont my family let the cat out when there's a bird?

Because they are attempting to train your cat not to kill. It's fine to do this. You can't stop liking a cat or dog from doing what their instincts tell them to do, but you can certainly discourage certain instincts. Some people allow their cats to kill, some people don't. It's probably more ethical to try to prevent a cat from killing, because that saves all these small animals from a lot of fear and pain, and your cat doesn't need to hunt to survive. They're doing a good thing.

Domestic cats (household cats) are not part of "the circle of life outside" anymore.

Birds and mice and anything else a cat may find can also carry deadly diseases that your mom will be the one dealing with at the vet and needing to pay for.

House cats are fed (hopefully) well enough that it doesn't need to catch food outdoors because it's hungry so it's only catching birds due to hunting instincts (like chasing your wiggling hand) and it won't eat the animal.

That's a waste of life.

If this were nature, there wouldn't BE any domestic cats to catch birds at all. I like cats but they've become a real problem to the native bird population.

Also, there are a lot of fledglings on the ground right now. They don't have a chance. Go give your cat a can of tuna, she'll get over it.

It's not Nature for a domestic, well fed animal to go out and kill a bird. When a wild animal kills something it's for survival. Domestic cats can decimate the bird and other wildlife population, and it's really needless.

Did you forget that birds have a right to live and your cat is a domestic cat not a wild cat? It doesn't need to eat birds to survive. Neighbors feed birds and enjoy them in their yards. Killing birds is not necessary nor is it good for the environment. Your cat should be indoors.

my cat will try to attacl birds but no luck. hes so fat. its adorable XD