National Geographic : 1946 Sep
()j Aatlonal ueograpnic society lKocacnromne Dy Artnur A. Allen Visibility Zero when Viewed from Above! A Female Willow Ptarmigan Almost Matches the Reindeer Moss So protectively colored is she that one can pass within three feet of an incubating bird without seeing her. To overcome this camouflage, the photographer lowered the camera to ground level and caught her in silhouette. In winter this Arctic dweller lives on birch and willow buds projecting above the snow.