Sheep devour native forest trees that rare birds rely on for food.

Many researchers have thought that in such situations the birds must rely, at least partly, on visual cues.

Many nesting birds rely on them for food especially in the months of February and March.

The birds instead rely on stores of fat.

The lack of visual cues has led some researchers to speculate that the birds must rely on the earth's magnetic field to navigate.

Based on the behaviour of the other subspecies, it is likely that the bird relied upon fruiting plants for food.

Other researchers suggest that pesticides may simply have killed off too much of the insect prey base the birds rely upon.

Until recently, it was assumed that other birds rely on different clues to guide them home.

As a nocturnal hunter, the bird relies almost entirely on its acute hearing to locate prey.

Many migratory birds rely on Harlan county Reservoir each year as they pass through.