Nesting often high in the redwoods’ canopy, the marbled murrelet faces new and longstanding risks. …Russian fur traders settled at Fort Ross on the rock-studded California coast in 1812, felling a grove of towering redwood trees for lumber to build a fort, homes and a church. More than two centuries later, the fort is a state park, and the redwood grove has regained the shady, canopy feel of old-growth forest, with a fern-bedecked floor and a creek purling beneath. But is this habitat close enough to old growth for the marbled murrelet, a quirky little seabird the size of a robin that comes ashore each year to lay an egg on a large, high branch deep in the redwood forest? Researchers are trying to answer that question by using advanced technology, including artificial intelligence, to more easily locate the elusive birds, whose numbers have declined significantly in the region. [to access the full story a NY Times subscription is required]