Have you considered it was you, another animal species, that was perceived as being the attacker, pursuer, aggressor, or predator? The Spruce Grouse may have been acting in a defensive manner against a perceived threatening other animal.

All too often human centric hubris combined with a wider ignorance of the universe fails to consider that it is the human species that is the most dangerous, destructive, and aggressive. Humans are after all scientifically classed as part of the animal kingdom.

Ever see shows like When Animals Attack or Top 10, 25, 100 Dangerous Animals? When will the human animal be included in the entertainment? Maybe, never because it's abrasively counter cultural to the ingrained notion humans are apart and above the rest of Nature?