Holy Cr-p, is that the pellet bouncing off its head!?!

I will say that my last time at the dairy I shot a dove that went right down which just dropped like a stone, BUT upon retrieval I could not see an entry or exit wound. I was using my 25 cal Taipan set at 30 FPE, so using the process of elimination I thought maybe the dove was knocked out. When I retrieved the dove I decided to wring the neck, just in case.