This video from the USA says about itself:
20 September 2017
A Blue Jay Wolf Pack surrounds a much larger Green Heron hunting behind the Backyard and mercilessly attacks and harasses it until it moves on. Unlike perching hawks and eagles which are slow – the nimble Green Heron is one bird that can take out a Blue Jay that gets too close with its sword tip sharp bill attached to a neck that can strike far and lighting fast.
The Blue Jays seem to know how dangerous this big bird is and display unusual behavior in confronting it. They are quiet and surround it just like a pack of wolves – taking turns attacking it so the Heron can’t focus on one bird to strike and kill. One of the most fascinating encounters I’ve ever seen in the Backyard.
You may think of Herons as hunting fish etc in the water, but they are also quite adept at hunting in the trees above and around the wetlands as this one is doing. Snakes, frogs, baby squirrels, rats and mice and smaller birds are all on the menu. The Blue Jays continue to be the protectors of their own family, but also many other creatures of the Backyard, this aspect of their place in nature is often not known or overlooked.