For centuries, fishermen have used seagulls and other seabirds to help them find where fish were feeding. The concept is simple: find where the birds are feeding, and the fish will be feeding on the same thing. Many inland streams aren't frequented by cormorants, albatrosses or seagulls, but there are still birds that can provide clues to where trout may be hiding or feeding.
In moving water a stationary duck, goose, loon or swan can reveal the location of a submerged rock or log. These are areas where the current will provide a break for weary trout or cover for them from predators. Your cast may startle the duck, but a duck taking off usually won't spook a trout.
Swallows are fast-moving, insect-eating birds that are valued by those with waterfront property for their appetite for mosquitoes. They are most active around a stream or pond when there is an insect hatch - the same time many trout are gorging on the same insects. Even though spinners most resemble baitfish in the water, when the feeding mechanism is triggered in a fish, they will strike anything that looks edible - including your lure!
I discovered this by accident one day while fishing a large pileated woodpecker was working on a dying tree across the stream, sending bits of wood into the water below. On a lark, I started casting below the woodpecker's perch and almost immediately started catching fish. It's not something I've had happen again, but if you see a woodpecker drilling into a tree over the water, the base of that tree is likely to be a good place to find feeding trout.