I have a couple of zebra finches who are at least 3 and a half years old. I know the lifespan of a zebra finches is about 4-5 years typically. My girls seem pretty healthy still. They are pretty active and talkative still. They seem to puff their feathers slightly more often than they used to and bicker a little bit more often than they used to. But other than that, I don't see signs of aging. Does anyone know if there are signs that my birds are close to dying of natural causes? Is there anything I do to make sure they're comfortable when they're close?