These birds are slender birds of prey. Wings are long and when flying are often held in a shallow V when gliding. Males are gray above and white below; females brown (shown). Faces are unusually flat looking. They have a white patch on the upper side of the tail base.
Often seen flying over grasslands, especially marshes.
This was a long shot and the photo is highly cropped. Still it shows quite plainly that this raptor had caught a leopard frog (at least I can tell that when I zoom way in on the original).