Three birders were on the platform, and two birders were below, in front of the platform. One birder thought he saw a female Redstart darting in the trees on the nearby little peninsula to the left. A birder above started looking and glimpsed the bird as well -- but he determined it was a male Redstart.
A friendly disagreement ensued. Peter Burger, a photographer, happened to get a "grab shot" of the bird -- a male Redstart, for sure.
When the folks below saw the photo the following day, they realized they had been looking at a totally different bird, likely because of the different vantage points.
Thanks to photography, the mystery was resolved.
Is there a word for this, sort of like a parallax view?