As stated in Wikipedia:

Bokeh (from the Japanese boke ぼけ, “blur”) is a photographic term referring to the appearance of out-of-focus areas in an image produced by a camera lens. Different lens bokeh produces different aesthetic qualities in out-of-focus backgrounds, which are often used to reduce distractions and emphasize the primary subject.

These images were taken in September 2007 at the John Heinz National Wildlife Refuge at Tinicum.