While both seek winged prey, Merlin, formerly known as the pigeon hawk, concentrate on birds, and American Kestrel (despite its former name ‘sparrow hawk’) on insects. Difference in prey choice relates to difference in foraging style: Merlin, pursue prey in a low, straight flight; American Kestrel hover, hawk and swoop.

Stanford Note: One comes to expect to see the jay-sized kestrel at the Dish, up from Stanford Avenue. So reliable is its presence on the hilltop, that a Merlin (mostly seen on campus during migration or in the winter), may come an go undetected.