Cetaceans will strand if they are malnourished, sick or confused.
Separated from its pod, a young dolphin or porpoise may struggle to feed itself and subsequently strand from weakness.
Pilot whales are very family-oriented, so if any of them strand due to age or illness, the entire pod will follow the stranded whale up onto the beach. This is the primary scenario of a mass stranding event.
Larger whales only occasionally venture into shallower waters such as the English Channel and southern North Sea, which are exceptionally shallow channels around our coasts. Used to deeper water, their sonar can be confused by gently shelving beaches or estuaries, causing them to strand accidentally.
Whatever the reason for stranding, a cetacean needs immediate assistance and medical assessment before any attempt is made to return it to the water. Historically, only 20% of single-stranded cetaceans have been healthy enough to be refloated, compared with over 60% of mass-stranded animals.