Males are brighter than females with slatey blue wings and back, dark head and dull facial markings.
The underside is is rufous with dark streaks. The tail is slaty grey with a dark terminal band. Females are uniformly brown with light, brown streaked undersides. Immatures resemble the female. Merlins are found worldwide, breeding in the norhtern latitudes and migrating south into Mexico and South America, the Mediteranean, the Middle East and southern China.