I agree, strongest category so far for me as well. Any one of these, as well as those that did not make my top 5 (tonight, right this minute) could easily have secured a 5 for me. Wonderful collection. My thinking in this moment:
I love everything about Gulp–the unusual perspective, the fact the viewer still sees the GBH eyes, and the timing which froze the peak of the action at this moment, not when the actual meal commenced.
I included the Bateleur/Jackal Standoff among my five picks for the behavior depicted, and the backstory implied.
I love the position of the two Kingfishers relative to one another, and how clearly I can see what the male is presenting. The fact that these birds are such fast flyers upped the ante for me on this one too; I like the slight wing blur suggesting that motion while everything else is sharp.
The Kung Fu Eagles–I like the position of each bird in this image, how the photographer managed the exposure, and the added bonus of photographing in falling snow.
I reacted emotionally to the Red-necked Grebes. I assume I am seeing the fog of their breaths as they call and the lack of a clear horizon serves to isolate these two birds in a world of the their own, thanks to the photographer’s choices of framing and exposure. I love everything about the image.

all Great Pictures! Congrats to all!