Floating flocks of Shearwaters

On the boat back and forth from Espanola, the sea was blanketed with patches of small birds, alternately floating calmly on the swells and erupting into a frenzy, snatching at schools of small fish.

At the time, I thought they were Petrels, but on closer examination they turned out to be Galapagos Shearwaters (Puffinus galapagensis or subalaris), a similar endemic species that forages the sea between islands, often in the company of other birds. The flocks I watched were interspersed here and there with Brown Noddies (Anous stolidus galapagensis).

One flock appeared to be following a pod of common dolphins that themselves were following a school of herring or other small fish. Once the dolphins located the school, the Shearwaters flushed to join the fray. They beat their wings furiously in spurts, then glide barely above the swells, their wingtips often barely touching the water. They enter the water with a short plunge, snatching fish close to the surface.

Galapagos Shearwaters are dark brown above from head to tail, with a stark white underside. In comparison, the Galapagos Petrel has a distinctive white forehead and a shorter bill.