The Merlin (Falco columbarius) is a species within the genus Falco, which is a group of birds of prey that also include about 40 other species that are scattered all around the world. Falcons are characterized by fast flight (sometimes very fast!), very sharply pointed wingtips, and a preference for eating other birds, which they catch in flight.
Members of the Falco genus are also distinguished by an unusual adaptation on their sharply hooked beaks. This adaptation is a notch in the upper portion, or mandible, of the beak, and it is called a tomial. The tomial tooth functions to dislocate the vertebra in the neck of their prey to quickly kill it.
Falcons frequently hunt by flying high in the air and spotting their prey from above. They then dive at high speed and strike their target in the air. They usually do not grab their prey at this point but rather strike it with closed feet to stun it. Another common hunting method of this genus is to perch on a tree, power pole, etc., and watch for prey which they then pursue in a high-speed tail-chase that can sometimes last for several minutes.
Like many birds of prey, female and male birds are different in size — a trait that is particularly dramatic in the Falco genus. The females are commonly about ten percent larger and about thirty percent heavier than the males.
The Merlin, specifically, has nine subspecies that are divided into two groups. One group has three subspecies that are all found in North America (the first three listed below). The other group has six subspecies that are all found in Eurasia (the last six listed below). The two groups may be on the verge of becoming two distinct species as they have been separated from each other for over a million years and likely have little to no gene flow between them. The nine subspecies are:
- F. c. columbarius breeds in Canada and the northern United States of America to the east of the Rocky Mountains.
- F. c. richardsonii is found in the Great Plains in central North America.
- F. c. suckleyi is found along the Pacific coast of North America from Washington State to Alaska.
- F. c. aesalon breeds in northern Eurasia from Great Britain to western Siberia.
- F. c. subasealon is found in Iceland and the Faroe Islands between Iceland and Great Britain. Likely interbreeds with F. c. aesalon.
- F. c. pallidus breeds in central Asia between the Aral Sea in the west and the Altay Mountains in the east.
- F. c. insignis breeds in eastern Siberia.
- F. c. lymani breeds in the mountains of eastern Kazakhstan and the surrounding area.
- F. c. pacificus breeds in eastern Russia.
Taxonomy at a Glance
- Domaine: Eukaryota
- Kingdom: Animalia
- Phylum: Chordata
- Class: Aves
- Order: Falconiformes
- Family: Falconidae
- Genus: Falco
- Species: Falco columbarius
How to Identify a Merlin
Overall, Merlins are small, stocky, dark falcons.
They have a pale line over the eye, an indistinct malar (or mustache) mark, a solid dark back, a thick chest, a light-colored breast and belly with dark vertical streaking, relatively short wings as compared to other falcons, and a relatively long tail.
However, within these general traits is a lot of variation from subspecies to subspecies and sex to sex.
Across continents and subspecies, males are usually lighter in color, more grey-toned, and less heavily streaked than the darker, more brown-toned, and more heavily streaked females. Also, across continents and subspecies, juvenile birds look pretty similar to the adult females.
Some subspecies, such as F. c. pallidus and F. c. richardsoni, are much lighter in color, with the lighter males being a very pale grey. Other subspecies, such as F. c. subaesalon and especially F. c. sucklyi, are much darker. All the species taken together tend to form a gradation of coloration between these ends of the spectrum.
When in flight, Merlins flap their wings with swift, powerful flaps. They are very active in flight, rarely gliding, and also tend to have very direct flight paths moving from place to place in straight lines across the sky.
Where Do Merlins Live: Habitat
Merlins are the most northernly living species among the small falcons. They prefer to live in open habitats such as scrublands, prairies, grasslands, and open woodlands, but they avoid very dense woodlands and very arid areas. Their geographic range is circumpolar and includes Alaska, Canada, Iceland, Great Britain, Scandinavia, Russia, and northern Asia. Merlins migrates south in the non-breeding season to Central America, the northern edge of South America, Europe, Northern Africa, the Middle East, and southern China. During migration, Merlins will use just about any habitat type. Some small populations are resident and so do not migrate.
Elevation can range from sea level to tree line, which varies with latitude, but commonly up to 2,000 meters and extending up to 3,000 meters during migration.
Merlin Diet and Feeding
As is true of most falcon species, Merlin feed primarily on birds (particularly during the breeding season) which they capture using their agility and speed. The size of bird can range from as large as pigeons and small ducks, to as small as songbirds of almost any species. In urban areas, House Sparrows are a very common component of Merlin diets. Doves and pigeons are so commonly hunted that the species’ scientific name, columbarius, means dove! Other species that are also eaten include dragonflies (which are captured and consumed on the wing), butterflies, small mammals (particularly bats, but also rabbits and small rodents), and occasional reptiles. These non-avian prey items are hunted more often during the non-breeding season.
Merlins often engage in tail-chases using their speed to overtake prey in flight. Merlins are very successful hunters, with almost 50 percent of their hunting attempts ending in success in favorable conditions. If they have extra food, Merlins will cache food in a safe location and come back to eat it later.
Merlin hunts often include very low flights of less than three feet above the ground and the use of trees and bushes for cover. The Merlin will then surprise their intended prey. Sometimes pairs will hunt together with one individual startling the prey, allowing the other individual to catch them.
Partitioning of preferred prey species tends to occur, which means that males and females target different species of prey. This helps to avoid situations where the male and female of a pair directly compete with one another, which allows pairs to bring an overall larger number of prey items back to the nest. This partitioning is driven by the fact that male Merlins are smaller than female Merlins. This size difference is common in birds of prey.
The members of a pair of Merlin are generally monogamous through the breeding season. Male and female Merlin Falcons may spend as much as a month exploring possible nesting sites before settling on one to use in a particular year. Breeding can begin as early as February and will extend into July.
Nests are varied and include shallow scrapes on ledges, abandoned nests of other birds or prey or corvids such as crow or ravens, and even spaces on the ground.
Regardless of the location, adults do little to no work actually constructing a nest. Instead, they will do a bit of work to scratch out a shallow depression in whatever substrate they are nesting on (or no work at all if using an abandoned nest), and lay their eggs in that shallow depression.
Clutches usually range from 3 to 6 eggs but can be 1 to 7. Incubation lasts from 28 to 32 days. The female generally incubates the clutch and is provided with food by the male.
A baby falcon is called an “eyas.” Eyas fledge from the nest about 27 to 32 days after hatching, which is when the young birds generally first take to the air.
The eggs are a sandy brown color with densely scattered speckles or blotches of brown or cinnamon. These eggs are smaller than a chicken egg — being only about 1.5 to 1.7 inches in length.
Merlin populations are stable throughout most of their range, and they are increasing at a rate of approximately two percent per year in North America. However, this increase still represents a recovery to the pre-1960s population level. The declines in the 1960s through the 1990s was largely due to DDT and other pesticides being used heavily and causing massive reproductive failure.
Population estimates that are the most reliable are those using data collected during the breeding season. The global breeding population that is estimated to exist is about 3.2 million birds.
Is the Merlin Endangered?
No, Merlins are rated as low conservation concern. This is due, in part, to the wide geographic range of this species and the overall stable population trends of this species. Population trends of this species in North America, in particular, are increasing, and the species is spreading into more suburban habitats.
Some of the more significant threats that Merlins face include collisions with windows, power lines, and other human-made structures.
As was common in a very large number of other species of bird of prey, Merlin populations were greatly reduced because of the use of insecticides such as DDT and others, which caused extensive reproductive failure.
Merlins have been known to follow behind other raptors such as Sharp-shinned Hawks as they hunt in order to capture prey that is flushed out of concealment by the first hawk.
Merlins are very fast and aggressive birds that are unlikely to tolerate the presence of another bird of prey. They have been widely known to attack much larger raptors, even those as big as Golden Eagles. And with typical flight speeds of thirty miles per hours, even a bird as small as a Merlin is a formidable opponent.
Given their small size, one might expect Merlins to be frequently eaten by larger predators. However, they are aggressive enough that most other predators avoid them. Some exceptions are the Peregrine Falcon, different species of Eagle-Owl (of this, the Great Horned Owl is a member), and different species of goshawk.
In the wild, Merlins live an average of around three years. About a quarter of young Merlins do not survive their first winter. The oldest known wild Merlin lived to be thirteen years old.
Answer: No. While Merlins are small falcons, they are still a bit bigger than the world’s smallest falcon species, the American Kestrel.
Answer: Merlins have been popular falconry birds since the medieval period and remain so to this day. Historically, this species was flown by the ladies of the court, which is how it got one of its early names.
Answer: The modern name “Merlin” is derived from the old French term for this species which was “esmerillon.”This French name, in turn, was derived from a Proto-Germanic word for falcon, which was “smirilaz.”
- Ferguson-Lees, J. and D. A. Christie. (2001). Raptors of the World. Houghton Mifflin Company, New York, NY, USA.
- Johnsgard, P. A. (1990). Hawks, eagles, and falcons of North America. Smithsonian Institution Press, Washington D.C., USA.
- Pyle, P. (1957). Identification Guide to North American Birds: a Compendium of Information on Identifying, Ageing, and Sexing “near-Passerines” and Passerines in the Hand. Slate Creek Press, Bolinas, CA, USA.
- Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.
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