Federal wildlife officials are investigating a die-off of Alaska seabirds that stretches from north of the Bering Strait to the Gulf of Alaska. The deaths may be linked to warming ocean water, which has affected the birds' prey. Carcasses examined so far have shown no indication of disease, and tests are pending for harmful algal toxins. The birds have been found emaciated and starved. The die-offs have been associated with unusually warm water conditions, which have increased in recent years. The deaths have been widely dispersed and highly concentrated in the north Bering Sea and the southern Chukchi Sea, which is unusual.