Hi Dave, this is such a beautiful sparrow and settings look pretty nice. Loved the perch Pose and BG..HA is not ideal but acceptable. Only nit for me it looks like heavy NR is applied on bird but as you mentioned it was underexposed so while adding exposure noise must have been a problem.
Beautiful sparrow and I love the subdued lighting and colours. I like the perch despite the sawed-off top. If cropped I'd add a bit back at bottom for the perch's "valley" and moss. I too get the feeling NR was applied on the bird. Don't be afraid of ISO 800 with the 7D if that is what you need for more SS (rather than underexposing).
Thanks for the comments and suggestions. They always help. I agree a bit more of the moss would have been nice. I had been looking for other birds in some cherry blossoms and just simply underexposed this one.