Wow. I have been at it for about a year, but without too many results! I shot a Red-breasted Grosbeak too- but it is not nearly as nice. Keep up the good work! I have been considering getting a 400mm f/5.6 prime- they are supposed to be super sharp- but they don’t have IS.
I would not buy a lens for wildlife that did not have IS. Wildlife is most active when the light is at its lowest. Stabilization is needed. I considered that lens too. But turned it down for that reason. I got my Sigma for $700, barely used.
That is the deal breaker for me too. I was reviewing some pictures I have taken with the lens, and I found that some were actually very sharp, while most of my recent ones seem almost out of focus. Could it be the camera? These are some of the better ones. Sorry, I just realized that I changed the topic- I should start another.