The larger of the two siblings often kills the smaller. Throughout the west, pairs of eagles occupy their territory year-round. Kestrels breed in open land with scattered trees and in cultivated and urban areas. They readily accept nest boxes and compete with other hole-nesting birds for nest sites. These birds are commonly seen along roadsides, perched on telephone wires or hovering in the air.
Merlins breed in open woodlands and savannahs, sometimes in cities.
Pairs perform aerial acrobatics high over their nesting site. They often use abandoned nests of similar-sized birds. Males do all of the hunting from courtship through incubation and sometimes through the nestling stage. Females can capture heavier prey than can males. These birds were once known as Pigeon Hawks.