I just have to add this thought, as I don't think it's been brought up: Birds eat whole foods, not processed foods. If they do eat processed foods like dogs and cats and fish, they won't live that long. Seeds, nuts, fish - and certainly not pellets - are eaten by wild birds. There's omega-3 and omega-6 in them, but there's also vitamin E. Unlike most people, who take in omega-3 and omega-6 as oils where vitamin E is absent. Vitamin E keeps PUFAs from peroxidation chain reaction of these oils, which produce free radicals.
Perhaps it's also why people also get away with eating coldwater fish, and seeds, and nuts.
Perhaps it's also why people also get away with eating coldwater fish, and seeds, and nuts.