By Graham Garett Grove
Geographic Range
Merlins are found throughout the Northern Hemisphere. There are nine recognized subspecies worldwide, with three in North America: F. c. columbarius, F. c. suckleyi, and F. c. richardsoni.
Falco columbarius columbarius summers in eastern Canada, southward to Michigan and westward to the eastern border of the Great Plains. This subspecies winters in the Gulf States, eastern Mexico, northern Venezuela, Ecuador, and the West Indies.
The summer range of Falco columbarius richardsoni includes the interior of western North America. This subspecies winters in southern California, northern Mexico, and southern Texas.
Falco columbarius suckleyi is found in the northwestern coastal regions from northern California to Sitka, Alaska.
Biogeographic Regions:
nearctic 
(native ); palearctic (native ); oriental (native ); neotropical (native ).
Other Geographic Terms:
holarctic .
Habitat
Merlins favor open country, preferring grasslands, seashores, sand dunes, marshlands, steppes, and deserts. Merlins rarely live in forested areas throughout much of their range, but frequently breed in coniferous forests of the Northern Hemisphere.
These animals are found in the following types of habitat:
temperate ; terrestrial .
Terrestrial Biomes:
taiga ; desert or dune ; savanna or grassland ; chaparral .
Aquatic Biomes:
coastal .
Wetlands: marsh .
Physical Description
(9.84 to 12.99 in)
(23.62 to 26.77 in)
Male merlins have slaty blue, purplish, or dark umber-brown upper parts, streaked with black from the crown to shoulders and back. The tail is barred by dark umber-brown or blackish bands and is tipped in white. The underparts are cream to a rich buff with heavy longitudinally streaks of dark umber-brown or black coloration, except for the throat which is an unmarked white. The sides of the head are buff with fine darker streakings. The forehead and line above the eye is white. The beak is bluish horn; the cere and feet are chromo yellow; the claws are black; and the iris is deep brown.
Females and young are similiar to males in their markings, but differ from males in coloration. The upperparts are dark brown. The neck is streaked with lighter brown and the tail is banded in yellow bars with a white tip.
Falco columbarius bendirei (Bendire's merlins): Lighter in the upper parts than Falco columbarius columbarius. The tail is black with three white bars.
Falco columbarius columbarius (American merlins): (see description of Falco columbarius). In males, the cere and feet turn reddish with age.
Falco columbarius richardsoni (Richardson's merlins): Lighter overall coloration and the tail is marked by five dark and six white bands.
Falco columbarius suckleyi (Black pigeon hawks): Darker in overall coloration than Falco columbarius columbarius. The throat of males is streaked with black markings, while the lower body parts are brownish-black with chestnut and white markings. The lower parts of young males and females are heavily marked with dusky coloration and the spotting is either faint or absent from the wings.
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: sexes colored or patterned differently.
Reproduction
Merlins breed once yearly.
Merlins breed from April to July, depending on the latitude.
Males arrive to the breeding area before the females, usually returning to the same general area year after year. Nesting pairs don't necessarily use the same actual site each year. In open country and grassland, nests are generally scrapes located in dense vegetation. In regions of sand dunes, dune grasses may be used to create a nest. Even in wooded areas, nests may be scrapes, but empty crow nests are preferred. During the nesting period, Falco columbarius become highly aggressive towards other raptors and crows in the area. This aggressive behavior towards other predatory birds is beneficial to other woodland song and ground birds in the nesting range; since Falco columbarius hunts only in open country, thereby leaving the woodland birds relatively free from predators during the mating season. Normally the nest contains four to six eggs measuring 1.5 x 1.22 inches. The eggs are laid at two-day intervals. The coloration of the round oval eggs are variations of light buff white almost obscured by a regular pattern of rich chestnut-brown, purple and chocolate blotchings.
The eggs are laid in early April to early May in the southern ranges and in late May through June in the North. The female is the main incubator, although the male does share in the duties. The incubation period lasts 25-32 days. At the end of the incubation period, the eggs hatch in intervals.
Quills appear on the young after fourteen days, and by eighteen days the down is almost completely covered with feathers, except in the head region. Flight is achieved at 25-30 days after hatching.
Upon leaving the nest, the young remain nearby for several weeks until they are mature enough to migrate southward. Within a week's time of leaving the nest, the young are capable of distance flights, and at two weeks' time, they begin to catch insects. By six weeks the young are skilled in catching small birds, and shortly afterwards, they migrate southward from the breeding area. The success rate among the the young is exceptionally high, often three birds per nest survive to continue breeding.
Falco columbarius: Breeds throughout northern Europe, Asia and North America.
Falco columbarius bendirei: Breeds in northwestern Alaska to northern Saskatchewan and into northern California.
Falco columbarius columbarius: Breeds in eastern Canada to the eastern border of the Great Plains and southwards into Nova Scotia and northern Michigan.
Falco columbarius richardsoni: Breeding range is located in the Great Plains from southern Alberta and Saskatchewan to northern Montana and North Dakota.
Falco columbarius suckleyi: Breeding occurs only in western British Columbia and perhaps on Vancouver Island.
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
Behavior
Falco columbarius is not a social bird except in the mating season. During this period, the male and female share duties in raising the young. During incubation, the female remains on the nest while the male does the hunting. Rarely does the male visit the nest, often leaving the prey nearby for the female to retrieve. When the young are older, both male and female share hunting duties. Once the young leave for good, presumably the male and female return to their solitary life style. Flight (similiar to the flight of the swallow) is fast with steady wingbeats, often skimming in a low zigzagging pattern over the ground. Falco columbarius seldom soars. The call is a series of sharp "ki-ki-ki-ki-kee."
Key behaviors:
flies; motile .
Food Habits
Merlins prey mainly on small birds of the ground and low vegetation, including larks (Alaudidae), sparrows (Passeridae and Emberizidae), finches (Fringillidae) and ptarmigans and grouse (Tetraoninae). Some small mammals, lizards, snakes, insects, and - in North America - dragonflies, also make up a portion of the diet. The relative proportions are about 80% birds, 5% mammals, and 15% insects.
Primary Diet:
carnivore (eats terrestrial vertebrates).
Animal Foods:
birds; mammals; insects.
Economic Importance for Humans: Negative
The diet of Falco columbarius consists mainly of small birds, including many small birds which benefit agriculture and forestry. In the northern the breeding range, Falco columbarius individuals sometimes attack small domestic poultry; however, these attacks are quite rare.
Economic Importance for Humans: Positive
Merlins occasionally prey on agricultural insect pests, such as grasshoppers and crickets. These small falcons are also widely used in falconry. Considered a lady's gaming bird, Falco columbarius is relatively easy to train for small game hunting and usually returned to the wild after a season.
Ways that people benefit from these animals:
pet trade ; controls pest population.
Conservation Status
IUCN Red List: [link]:
Least Concern.
US Migratory Bird Act: [link]:
Protected.
US Federal List: [link]:
No special status.
CITES: [link]:
Appendix II.
State of Michigan List: [link]:
Threatened.
Falco columbarius is widely distributed, but nowhere common. With expanding human development, the breeding habitats and hunting grounds of these falcons are being destroyed rapidly. This species is listed as threatened in the state of Michigan.
Other Comments
For many years Falco columbarius was considered two, separate species: European merlins, Falco aesalon and American merlins, Falco columbarius. J.L. Peters in 1931 realized that Falco aesalon was a sub-species of Falco columbarius. Currently, Falco columbarius consists of seven European sub-species and four American sub-species: Falco columbarius bendirei, Falco columbarius columbarius, Falco columbarius richardsoni, and Falco columbarius suckleyi.
Contributors
Graham Garett Grove (author), University of Michigan.
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
