The Tundra Swans were in a field near the road. It's common in Pocosin Lakes National Wildlife Refuge. While naturally wary and rightfully so, they are not hunted in the refuge and they are fairly used to vehicles along the road. On this day they were on the edge of the field. I parked and waited, and readied my camera and lens in my vehicle's window as the group of foraging swans made their way toward me. In this situation, the car was the best blind. They see the car, obviously, but if my movements were slow and limited, they would not be alarmed.
All was well. The swans continued to feed and some approached too close to photograph with my 600mm lens. I did not dare move inside the car when they were close. And that's when I noticed another car approaching. The car stopped next to the swans. A door flings open and one of the occupants runs around the car to snap a photo with their phone. All of the swans immediately went on alert and moved a safe distance away from the road. The person got back in their car and moved on. The swans resumed feeding after several minutes.
Sometimes, a car can be the best blind when the birds are used to cars. Birds will usually tolerate your presence as long as your movements are limited and especially if you position the car in way that the birds approach you rather that you approaching the birds.