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Merlin Life History


ForestsMerlins breed in open and semiopen areas across northern North America. The boreal subspecies usually nests near forested openings, in fragmented woodlots, near rivers, lakes, or bogs, and on lake islands. The Pacific Northwest subspecies seems to nest mostly in coastal areas and along rivers. The prairie subspecies nests in shrubs and trees along rivers and in small groves of deciduous trees planted as wind breaks. Merlins are increasingly breeding in towns and cities, where they often take 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 habitat across the western United States 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.Back to top


BirdsMerlins eat mostly birds, typically catching them in midair during high-speed attacks. They often specialize on hunting a couple of the most abundant species around; prey are generally small to medium-sized birds in the 1–2 ounce range. Common prey include Horned Lark, House Sparrow, Bohemian Waxwing, Dickcissel, Least Sandpiper, Dunlin, and other shorebirds. They don’t stoop on birds the way Peregrine Falcons do; instead they attack at high speed, horizontally or even from below, chasing the prey upwards until they tire. Other prey include large insects such as dragonflies, bats caught at cave openings, nestling birds, and small mammals. Merlin pairs have been seen teaming up to hunt large flocks of waxwings: one Merlin flushes the flock by attacking from below; the other comes in moments later to take advantage of the confusion. Back to top


Nest Placement

TreeMerlins lay their eggs in abandoned nests of crows and hawks, in either conifers or deciduous trees of semiopen habitats. 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.

Nest Description

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 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
Egg Length:1.5-1.7 in (3.8-4.4 cm)
Egg Width:1.1-1.3 in (2.9-3.3 cm)
Incubation Period:28-32 days
Egg Description:Rusty brown marked with brown or chestnut.
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.
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Aerial ForagerLike 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. During the breeding season they are highly territorial around the nest, chasing away other Merlins and potential predators. Merlins are monogamous during a breeding season, but 80 percent find new mates from year to year. 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. Outside of the breeding season, Merlins are usually solitary. However, they sometimes migrate in loose groups, roost communally, or spend the winter in pairs. Adults may be preyed on by Peregrine Falcons, Great Horned Owls, Cooper’s Hawks, and Red-tailed Hawks.Back to top


Low Concern

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. 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. Their ability to colonize urban areas may be counteracting a decline in other parts of their breeding and wintering ranges from habitat loss.

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Dunne, P. (2006). Pete Dunne's essential field guide companion. Houghton Mifflin Harcourt, New York, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Sodhi, N. S., L. W. Oliphant, P. C. James, and I. G. Warkentin. 1993. Merlin (Falco columbarius). In The Birds of North America, No. 44 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington D.C.: The American Ornithologists' Union.

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