As we set out on our zodiac this morning our spotter called and directed our team to a group of hunting Short-beaked common dolphins (Delphinus delphis) that were hunting 2 nautical miles outside Calheta. The location of the pod was marked by a group of Cory’s Shearwater (Calonectris borealis), a bird species with a special relationship to the archipelago. Corys are estival breeders here in Madeira, which means that large groups of these birds, known as colonies, return to breed during the summer months. The season begins in May but many individuals journey here a little earlier to rest, scout some ideal nest spots and assess the prey abundance near the coastline.
This is best done in the company of marine predators, particularly dolphins since they tend to drive schools of fish to the surface when they hunt. Like all Procellariiformes Corys are a phillopatric species, meaning they return to their birth colonies to breed and this makes Madeira a very important habitat for these birds. It also means that some of these early birds know the islands waters well and are familiar with the hunting tricks of the predators they associate with.
Observing the birds try to snatch a fish while dolphins are hunting is probably the best way to distinguish the connoisseurs from the newcomers. Today the commons were hunting Garfish (Belone belone) a planktivorous fish that likes to feed in small schools directly below the surface. Smaller schools are trickier to hunt but the common dolphins have developed the perfect tactics to catch these small, nimble fish. The pod divides into small hunting parties of up to 3 animals and, while some dolphins drive the fish to the surface, another leaps through the school sending its terrified prey flying through the air, a crucial moment for the Corys to get a piece of the meal. To anticipate the moment and time their efforts correctly the birds often stick their heads into the water to follow the dolphins movements, very much like ducks. If the underwater pursuit takes a little longer, some birds take the time to clean their feathers before following the dolphins once more.
This just grows to show that any situation at sea is an experience and involves so many small but precious details. It’s our job and pleasure to point these out to our guests and make the most of these lovely moments out on the Atlantic.
By Paula Thake
Sightings of the day
10:00 Short-beaked common dolphins