The third episode of Earthflight continues the journey of the barn swallows and white storks from the previous episode as they reach Europe. Spoilers ahead.
Male white storks are shown arriving at their old nesting grounds. As they wait for their mates to return, they repair their old nests and chase off younger males that may try to steal their sites. Male swallows also arrive at their nests before females do and get around to doing similar activities. The slow-motion footage of swallows snatching airborne feathers for use as nesting material may visually be among my favorite sequences in not just this episode, but in the entire series.
This episode also shows other types of birds making the journey up north, such as common cranes, gannets, flamingos, and brent geese. In particular, barnacle geese are given a lot of focus as they fly up to their nesting grounds in the Arctic. Along the way they are attacked by a golden eagle (which is unexpectedly driven away by a flock of crows) and are forced to fly through a heavy rainstorm (which their waterproof feathers shield them from). After their young hatch, they, along with Arctic terns and skuas, manage to chase away a marauding polar bear in what may be the most awesome sequence in this episode.
Other scenes in this episode include an osprey fishing, a flock of starlings outmaneuvering a peregrine falcon, and sand martins catching emerging mayflies from the surface of a river (in slow motion, of course; Earthflight loves slow motion, to the point where I repeatedly used "slow-motion ____ grab" to describe what was going on when I live-tweeted episodes).
If I had to choose, this may be my favorite Earthflight episode. It may have been because most of the storylines were well wrapped up, or because I found the footage especially spectacular, or because European wildlife doesn't often get much airtime in documentaries. The one thing I may nitpick is that we never see what happens to the brent geese, uniquely of all the migrating birds they showed. They're shown flying along for one scene but are never given any followup, and it would've made the episode even better rounded had they done so.