State environmental officials said Wednesday that they now “strongly suspect” that avian influenza is responsible for the death of large numbers of seabirds washing up on Island shores.

Great shearwaters nest on small islands in the southern Atlantic Ocean when it is summer down there.

Long narrow wings and a fairly robust body, running along the water’s surface to become airborne, oceanic and a tube on top of their beaks to excrete excess salt. All are characteristics of shearwaters.

Shearwaters are a part of a group of birds known as pelagic species. They spend all their lives, except during breeding, on the open ocean.

Last summer numerous greater shearwaters washed up on the South side of the Vineyard.