When an Osprey ( a fishing-eating hawk ) returns from fishing to its nesting area with a fish like an alewife, a pollack, or a smelt, other Osprey's will retrace its flight path in hopes of good fishing. There is seldom such a response if the first bird brings back a winter flounder. Yet ospreys feed on winter flounder just as readily as on any other fish.
Which of the following, if true, contributes most to an explanation of the fishing behavior of ospreys as it is described above ?