Large birds are washing up and dying on the Cape Cod coast, and scientists are stumped on the mysterious illness.

The Cape Cod Times reports animal hospitals and rehabilitation centers have seen an increase in gannets at their facilities over the past few months.

With wingspans reaching up to 6 feet (1.8 meters), gannets are known for diving through the water from nearly 130 feet (40 meters) in the air.

The staff at the Wild Care Center in Eastham says 16 of the 21 gannets brought to the facility have died from the ailment. Necropsies on the birds have, so far, been inconclusive.

A wildlife technician with the US Department of Agriculture estimates about 100 northern gannets have been affected overall.

ASSOCIATED PRESS