One of my favorite quotes of all time comes from the nineteenth-century biologist Louis Pasteur, who told his audience, during a college lecture, "In the fields of observation, chance favors only the prepared mind." Pasteur didn't have natural history photography in mind, but his words certainly rang true today, when I was out at Avalonia's Henne Preserve to try to document the Great Blue Heron rookery. However, when I was checking the nests for moms busy incubating eggs, I felt a presence above me... a shade that turned out to be an Osprey hovering perhaps 15 feet above my head. It was a stirring sight, and, as it happened, I was fully prepared to take maximum advantage of this unexpected chance. On my dSLR was the Sigma supertelephoto, which was set to its maximum reach, 500mm, and ready to roll. I lifted the behemoth, focused quickly on the fish hawk, and held down the shutter to capture a burst of activity... and great good fortune.