Walsberg studied the effect of cattle grazing on a small ground-nesting song bird in northwestern Arizona. The author located 17 nests in the cattle-grazed pasture and 21 nests in the ungrazed pasture. Only 2 of the 17 nests in the grazed area were successful in fledging young, while 10 of the 21 nests in the ungrazed area were successful. Pictures of each nest were taken with a hemispherical fisheye lens which produced a 180 degree view from the nest. In the ungrazed areas, 66% of nests had vegetation occluding the nest in the upper hemisphere, while 39% of the grazed area nests had vegetation occlusion. Walsberg found only two nests that were directly trampled by cattle and noted that many predators of the junco were found in the area surrounding the grazing plot. Walsberg concluded that livestock grazing is the most pervasive and important source of habitat destruction in the western United States and it is drastically reducing the reproduction of the dark eyed junco.
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