k i read your question, and then the answers, and i felt like i really had to answer. you're absolutely right, some people on this site are so f*cking rude, its unbelievable. i asked a question the other day about whether a certain tattoo would fit better on my arm or calf, and i got soo much sh*t for it. people will always use the rudest terms to describe something they don;t like. in your case slag tag and tramp stamp. these are suuuuuch stupid, inconsiderate, unintelligent and dense terms. really shows how closed minded people are.
personally, i think that the blackbird will fit your lower back the best. and it isn't a tramp stamp, either... its a wide, flat space that can accommodate a large tattoo. it could go on your upper back, but depending on how dark and solid your tattoo is going to be, i think it may be a liitle too overwhelming for the top.
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[as a side note : ive noticed, when i look at women with one sleeve tattoo, it almost seems as though their tattooed arm looks larger than their non tattooed arm. i know its just an illusion my mind is playing on me because of all the decorated body art that makes it seem like the arm as more area. so i think this would happen with an upper back tattoo too (thats as large and dark as yours) not that it won't look nice by any means, but it will probably make you seem top heavy. that is why "tramp stamps" are usually appealing to people who dont hold stupid stigmas. its because it makes a woman appear curvier, if she has the right design on her lower back.]
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it depends how often you want to show it off too - if you want it to show a lot then upper back (but ask the artist to perhaps lighten the bird a little, by adding details rather than it being so much solid black everywhere). if you want to be discrete, than put it on your lower back. i think it would look awesome if the wings stretched out, and the top tips extended and curled around your hips a little. it would probably never show when youre older, if thats a concern, cuz your clothes would cover it.
whether or not people like the location, personally, your image would look best there because of the size, shape, and colour.