What a fun challenge this was, a very relaxed, easy to fulfil theme. So, thank you for introducing me to this process, something I have never seen before, does one tree really fill all those buckets?
In terms of the image itself your chosen wide open aperture has nicely softened background detail down so that we can concentrate on the tree itself. I find the lighting harsh and very contrasty I think it would have been better for you to have shot it in better light. The crop is a little inaccurate, with part of another bucket appearing right on the edge of the frame, and therefore distracting. Also your position includes a soft focus background shape clinging to the bucket, it would have been better to hide this behind the bucket.
You've received lots of novel suggestions for a title so in keeping with the rest of your commenters I really cannot let the side down can I, how about;
'birds air raid shelters'.
Well done, Sid