Hello. It's extremely difficult to pinpoint the exact age of a parrot, especially a sexually mature adult. What is for certain is that a 10 year old amazon is certainly sexually mature (they hit "puberty" around 5/6). Plus, not every adult parrot is aggressive due to hormones (some get more lovey), this is not amazon breeding season right now, and prior owners may have trained him appropriate behaviors so he is not out of control despite hormones. In the spring, you may notice subtle or extremely obvious signs of hormonal behavior for a few weeks. Some parrots do get it worse than others, but an increase in shredding, more aggressive, noisier than usual, or obvious sexual behavior all mean your bird is a healthy "teenage boy". These behaviors can be curbed by increasing the amount of shredding material, providing distractions from sexual behaviors (removing a too well loved toy, providing extra foraging, limiting daylight (waking) hours and being extra cautious regarding biting). Males tend to get it worse than females, but if you teach the bird distraction from the behaviors, most of them will mellow out after a few really nasty years (again, just like teenage boys, mean, destructive and horny for a few years lol). Our adopted male blue front is about 15 years old, and the first 4 breeding seasons, I wont lie, he was a nightmare, but we stuck with distracting him from his hormonal behaviors, and this past breeding season, he was much more relaxed. But back to the actual subject of age, and it's pretty much you will likely never know. Hormonal behavior only indicates they are an adult, and some older/mellower adults really don't display it noticeably anyways. I will say older birds (like 40,50+) have more muted colors, their nails and beaks grow faster and (for lack of better terminology) more gnarled, there are subtle differences in texture of feathers, some will have thin or bald patches that just don't grow in anymore (not related to illness or plucking), some develop cataracts, some develop arthritis....but all these things are often too subtle to notice if you haven't been around parrots of all ages for a while. If I were you, I would just assume he's around 10 and not worry too much about it. Does it really matter? A parrot of any age is capable of being trained, loved and giving love if you are willing to put in the effort to socialize him. We were told Kiwi was about 10 when we adopted him, and even if he's 20 or 30 or even older (or maybe younger), he's still a sweet little guy who's become part of our family. Best of luck with the little guy!
