The Merlin ( Falco columbarius ) is a small but fierce falcon found throughout the Northern Hemisphere. Previously known as the "Pigeon Hawk" in North America due to its resemblance to a pigeon in flight, the Merlin is a compact, fast-flying bird that primarily hunts small birds in mid-air. This article delves into the Merlin’s habitat, diet, hunting habits, nesting behavior, and conservation status, providing a comprehensive overview of this fascinating raptor.
Habitat and Distribution
Merlins breed in open and semi-open areas across northern North America, Europe, and Asia. Their habitat preferences vary depending on the subspecies and region.
North America
- Boreal Subspecies: Typically nests near forested openings, fragmented woodlots, rivers, lakes, bogs, and lake islands.
- Pacific Northwest Subspecies: Primarily nests in coastal areas and along rivers.
- Prairie Subspecies: Nests in shrubs and trees along rivers and in small groves of deciduous trees planted as windbreaks.
- Urban Adaptation: Increasingly breeding in towns and cities, often taking over crow nests in conifers planted in residential areas, schoolyards, parks, and cemeteries.
During migration, Merlins stop in grasslands, open forests, and coastal areas. They winter in similar habitats across the western and southern United States, along the Pacific coast to Alaska, and along the Atlantic coast to southern New England. Their wintering range extends south through Latin America as far as Ecuador.
Eurasia
Merlins inhabit fairly open country, such as willow or birch scrub, shrubland, taiga forest, parks, and grasslands like steppe and prairies, sand dunes, deserts, or moorland. They generally prefer a mix of low and medium-height vegetation with some trees and avoid dense forests as well as treeless arid regions.
Diet and Hunting Habits
Merlins are carnivores that primarily eat birds, typically catching them in midair during high-speed attacks. They often specialize in hunting a couple of the most abundant species around, with prey generally being small to medium-sized birds in the 1-2 ounce range.
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Preferred Prey
Common prey species include:
- Horned Lark
- House Sparrow
- Bohemian Waxwing
- Dickcissel
- Least Sandpiper
- Dunlin
- Other shorebirds
Hunting Techniques
Unlike Peregrine Falcons, Merlins do not stoop on birds from high altitudes. Instead, they attack at high speed, horizontally or even from below, chasing the prey upwards until they tire. This requires strong and maneuverable flight, with a typical flight speed of 30 miles per hour or faster during chases.
Other Prey
In addition to birds, Merlins may also consume:
- Large insects such as dragonflies
- Bats caught at cave openings
- Nestling birds
- Small mammals
- Rodents
- Reptiles
Cooperative Hunting
Merlin pairs have been observed teaming up to hunt large flocks of waxwings. One Merlin flushes the flock by attacking from below, while the other comes in moments later to take advantage of the confusion.
Diurnal Hunters
Merlins are diurnal hunters and rely on speed and agility to hunt their prey. They often hunt by flying fast and low, typically less than 1 m (3.3 ft) above the ground, using trees and large shrubs to take prey by surprise. But they actually capture most prey in the air, and will "tail-chase" startled birds.
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Nesting Behavior
Merlins are serially monogamous and pairs form for one season only. Their breeding season occurs typically in May-June and during this time birds perform aerial courtship displays. Merlins breed at two years old, though some start as yearlings. Most North American subspecies are migratory to some degree and return to their breeding grounds in the northern US and Canada by March-April. Courtship involves elaborate flight displays, including steep dives, rolling from side to side, and wing fluttering.
Nest Placement
Merlins do not build their own nests; they reuse old crow, raven, magpie, or hawk nests, making few, if any, modifications to the original nest. They mainly use abandoned crow or hawk nests which are located in conifer or mixed tree stands. In moorland-particularly in the UK- females usually make a shallow scrape in dense heather to use as a nest. Others nest in crevices on cliff-faces and on the ground, and some may even use buildings. They tend to choose nests with a good view of the surrounding area. On rare occasions, they nest in tree cavities, on cliffs, or on the ground. They only rarely reuse a nest in subsequent years. The dimensions of the nest can vary greatly depending on which species’ nest they reuse.
Nesting Facts
- Clutch Size: 4-5 eggs, sometimes 2-6.
- Egg Length: 1.5-1.7 in (3.8-4.4 cm)
- Egg Width: 1.1-1.3 in (2.9-3.3 cm)
- Egg Description: Rusty brown marked with brown or chestnut.
- Incubation Period: 28-32 days. Incubation is mostly by female, 28-32 days; male brings food to female, then he incubates while she eats.
- Condition at Hatching: Mostly helpless, with closed eyes. Nestlings have yellow feet and bluish bills, are covered with sparse whitish down, and weigh just under 0.5 ounces.
- Fledging: Hatchlings weigh about 13 g (0.46 oz) and fledge after another 30 days or so. They are dependent on their parents for up to 4 more weeks.
- Nest Helper: Sometimes first-year merlins (especially males) will serve as a "nest helper" for an adult pair.
- Reproductive Maturity: Merlins become reproductively mature at one year of age and usually attempt to breed right away.
Parental Care
The female lays 3 to 6 (usually 4 or 5) rusty brown eggs. She incubates them within 28 to 32 days while the male hunts to feed the family. Female remains with young most of time, brooding them when they are small. Male brings food, female takes it from him near nest and then feeds it to young. Age of young at first flight about 29 days.
Behavior
Like other falcons, the Merlin is a strong and maneuverable flier. A typical flight speed is 30 miles per hour, and can be faster during chases. Despite their small size, Merlins look powerful in flight; they flap their wings faster than Prairie or Peregrine falcons.
Territoriality and Courtship
During the breeding season they are highly territorial around the nest, chasing away other Merlins and potential predators. When courting, Merlins (particularly males) perform spectacular flight displays, including bursts of strong, level flight while rocking side to side in the air; deep U-shaped dives; and slow, fluttering flights in a circle or figure-eight near to a perched mate. Both sexes claim their territory by soaring high in the air near their nest. Males also make a slow landing next to their mate, keeping their legs outstretched, bowing the head, and fanning the tail; he may bring food for the female.
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Social Behavior
Outside of the breeding season, Merlins are usually solitary. However, they sometimes migrate in loose groups, roost communally, or spend the winter in pairs.
Predation
Adult Merlins may be preyed upon by Peregrine Falcons, Great Horned Owls, Cooper’s Hawks, and Red-tailed Hawks.
Vocalization
Merlins communicate vocally and are usually noisy near the nest and during the displays.
Conservation Status
Merlin populations increased nearly 2% per year between 1966 and 2019, according to the North American Breeding Bird Survey. This increase reflects their recovery from widespread declines in the 1960s due to pesticide contamination. Partners in Flight estimates the global breeding population at 3.2 million and rates them 7 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. The most serious threat to merlins is habitat destruction, especially in their breeding areas.
Range Expansion
Starting in the late twentieth century, breeding Merlins have been colonizing an increasing number of cities and towns, where they take advantage of abundant House Sparrows for food and old crow nests for breeding sites. In 1995, they started expanding into New York and northern New England and now breed across Vermont, New Hampshire, and Maine. Their winter range spread into the northern Great Plains between 1960 and 1990.
Field Identification
A rather small falcon, compact and fast-flying, the Merlin is a common breeder across the northern forests of North America and Eurasia. It feeds mostly on small birds, capturing them in mid-air in rapid pursuit. The Merlin is generally found in wild places, but since about 1960 it has become a common urban bird in several towns on the northern prairies; there it nests and remains to winter, relying on a steady supply of House Sparrows as prey.Most Merlins migrate, some northern birds reaching South America. Those of Pacific Northwest (race suckleyi) are mostly permanent residents. Some prairie birds (race richardsonii) have become permanent residents in cities on northern plains during recent decades, while others there still migrate.Relatively short-tailed. Female and immature brown above, male blue-gray above, all are streaked below. Dark tail is crossed by narrow whitish bands. In pale prairie form, male is almost sky blue above, while pale brown females can suggest small version of Prairie Falcon. A scarce blackish form lives along northwest coast, seldom wanders elsewhere. Most widespread form is intermediate in color. Sharp-shinned Hawk has similar markings but has wingtip rounded (not pointed), no white bands on tail.
Subspecies
There are nine subspecies. Three breed in North America: the Black Merlin ( F. c. suckleyi ) from the Pacific Northwest, the Taiga (or better-named Boreal) Merlin ( F. c. columbarius ) of northern forests from Alaska to Newfoundland, and the Prairie Merlin ( F. c. richardsonii ), a pale colored form that breeds in northern prairies and aspen parkland of the U.S and southern Canada. Six subspecies breed in Eurasia: the Icelandic Merlin ( F. c. subaesalon ) found on Iceland and the Faroe Islands, the Eurasian Merlin ( F. c. aesalon ) of northern forests from the UK through central Siberia, the East Siberian Merlin ( F. c. insignis ) which breeds from the Yenisey to Kolyma Rivers of Siberia except coastal regions, the Pacific Merlin ( F. c. pacificus ) found in the coastal Russian far east and Sakhalin Island, the Pallid (or commonly named Steppe) Merlin ( F. c. pallidus ) found in the Asian steppe region from near the Aral Sea to the Altai Mountains, and the Central Asian Merlin ( *F. c.
Physical Description
The male merlin has a blue-grey back, ranging from almost black to silver-grey in different subspecies. Its underparts are buff- to orange-tinted and more or less heavily streaked with black to reddish brown. The female and immature are brownish-grey to dark brown above, and whitish buff spotted with brown below. Besides a weak whitish supercilium and the faint dark malar stripe - which are barely recognizable in both the palest and the darkest birds - the face of the merlin is less strongly patterned than in most other falcons. The eye and beak are dark, the latter with a yellow cere. The feet are also yellow, with black claws.
Merlins and Humans
Although its small size makes the Merlin unsuitable for hawking large quarry, in Medieval Europe it became popular as a "lady's hawk" and was used in the now classical ringing flights directed at the Skylark ( Alauda arvensis ). Catherine the Great and Mary Queen of Scots were among the more famous enthusiasts of this sport. These lark flights have continued as a tradition in Great Britain, although falconers are now under public pressure to stop the sport. In North America, a small number of falconers fly Merlins at avian quarry ranging from sparrows to doves.