Minas Alis - Sea bird

The bird.

High above the oceans of Levis, soars the Minas Alis. With a wingspan of 25m, the Minas preys upon small kraken and ship alike. With grey back plumage and a white underbelly, these carnivorous birds mix aerial attack and long, underwater hunts with gills behind the axis of their jaws. They have a medium sized narrow beak with a bit of a small hook on the end for breaking things open. It communicates through a mixture of whistles and rapid beak clicks.
Even sharks are not safe, plucked from oceans mid hunt.
They are paired hunters, with each couple covering an territory alone. Their nests tend to be in large hollows in sea facing mountains.

Customs

Coastal children have a jetty game where one child stands on the jetty, eyes closed, flapping their arms as their fellows make animal sounds in the water. When they find their prey they divebomb into the water nearby, arms flailing to catch their victim/friend.

Protection

Most coastal towns employ watchtowers and reinforced shelters to protect against attacks by these creatures.
Boats employ many measures to protect against them; enchantment magic, specialty fireworks, or rigging that fans out to look like large birds themselves.