What action caused dogs to earn the "Springer" designation over ancestral land spaniels?

Answer

Flushing or springing game birds into the air

The historical lineage of the breed traces back to general 'land spaniels' existing for centuries. The specific designation 'Springer' arose because these dogs were bred specifically to flush, or 'spring,' game birds directly into the air, making them available for hunters or falcons to pursue. This function separated them from the smaller spaniels, which the Duke of Norfolk in the 1800s kept for hunting woodcock, those smaller dogs eventually becoming recognized as Cocker Spaniels. The longer-legged dogs capable of this flushing action became known as Springer Spaniels, a specialization that led to the official recognition of the English Springer Spaniel breed later on.

What action caused dogs to earn the "Springer" designation over ancestral land spaniels?
Dogbreedspaniel