2010 Wildlife Facts - Merlin

Photo of the Merlin/Falc��n Migratorio

Merlin, Pigeon Hawk (Eng.), Esmerejón, Falcon Migratorio (Sp.), Falco columbarius (Sci.). Small North American falcon species – winter migrant to Central/South America and Caribbean.

Photo: © Kevin T. Karlson. Information compiled by Alan Mowbray, Interpretive Media Writer, EYNF/LEF

General Information

Taxonomy: Class – Aves ; OrderFalconiformes; FamilyFalconidae; GenusFalco; SpeciesF. columbarius. A small North American bird of prey, first described by Linnaeus in 1768.


F. columbarius adults of both sexes measure from 9.4 to 11. 8 inches (24 to 30 centimeters) in body length, with a wingspan from 20.9 to 26.8 inches (53 to 68 centimeters), typically weighing between 5.6 and 8.5 ounces (160 and 240 grams). They have a short, dark colored, hooked beak; long, pointed wings, broad at the base. Males are blue-grey (slate) colored above and are buff to orange heavily streaked with black to reddish-brown below. Females and young are brownish-green to dark brown above and whitish-buff, spotted with brown below. Both males and females have long, boldly banded tails.


Merlins are carnivorous aerial predators, relying on speed and agility to hunt and capture their prey. They typically hunt by flying from tree perches when prey is sighted, but will also fly fast and low less than 3 feet (1 meter) above the ground to flush-out prey. Their diet consists primarily of small birds, but they will also occasionally consume small mammals such as mice and bats and large insects, small snakes and lizards. Their song is a rapid “Klee-klee-klee.” Merlins breed during the summer in the northern United States and Canada between the months of May and June. Breeding pairs are generally monogamous, at least for a breeding season – females typically lay a clutch of 3 to 6 rust-colored eggs in nests that have been abandoned by crows or hawks. Incubation by the female lasts from 28 to 32 days while the male hunts to feed the family. The young fledge 30 days after hatching but are dependent on their parents for up to four more weeks. Merlins become sexually mature at one year, usually attempting to breed immediately. The oldest wild bird known was recorded in its 13th winter in 2009.


F. columbarius is a common winter resident in open forestland, grasslands, open cultivated fields, mangrove swamps, estuaries, and seacoasts in Puerto Rico. Arriving around November, they are often observed inside El Yunque and in municipalities adjacent to the Forest. A particular female has been observed perching on the same Ceiba tree near the Puente Roto bridge and in a tree snag close to the Angelito Nature Trail head for over seven years!


The Merlin is listed as non-threatened by the International Union for the Conservation of Nature (IUCN), but the speciels may possibly be in decline due to the adverse effects of pesticides.

Additional Information

USDA Forest Service
El Yunque National Forest
HC-01 Box 13490
Rio Grande, PR 00745
787 888 1810

Raffaele, Herbert A. (1989), Birds of Puerto Rico and the Virgin Islands, Princeton University Press, Princeton, New Jersey, Plate, p.20; Text, p.61.

Oberle, Mark H., (2000) Puerto Rico’s Birds in Photographs, Second Edition, Editorial Humanitas, San Juan Puerto Rico, Text and photograph, p.58.

List of Mamals by Month

January: Antillean Fruit Bat February: Tarantula Hawk March: Puerto Rican Vireo
Illustration of the Antillean Fruit Back/Murciélago Cavernicola
Photo/Link of the Tarantula Hawk
Photo/Link of the Puerto Rican Vireo/Bien-te-veo
April: Puerto Rican Garden Snake May: Little Fire Ant June: Green-backed Heron
Photo/Link of the Puerto Rican Garden Snake/Culebrita de Jardín
Photo/Link of the Little Fire Ant / Abayalde
Photo/Link of the Green-backed Heron/Martinete
July: Big Brown Bat August: Mottled Coqui September: Puerto Rican Ground Lizard
Photo/Link of the Big Brown Bat/Murciélago Marrón Mayor
Photo/Link of the Mottled Coqui/Coquí de Eneida
Photo/Link of the Puerto Rican Ground Lizard/Siguana
October: Merlin November: Sooty Mustached Bat December: Common Worm Snake
Illustration of the Suoty Mustached bat/Murciélago Bigotudo menor
Common worm snake/Víbora común