Merlins are small, compact, and incredibly fast falcons found in Oregon, particularly during migration and winter, though some subspecies breed here. Like American Kestrels, they exhibit **sexual dimorphism**, with noticeable differences between males and females in both size and plumage.

It's important to note that there are three subspecies of Merlin in North America (Taiga, Prairie, and Black), and while all can be seen in Oregon, the Black Merlin (Falco columbarius suckleyi) is the darkest and most common breeding subspecies in the Pacific Northwest, including Oregon. This can affect how pronounced the sex differences appear.

General Characteristics (Both Sexes)

Size: Slightly larger and more robust than an American Kestrel, but still a small falcon, typically 9.4-11.8 inches (24-30 cm) long with a wingspan of 20.9-26.8 inches (53-68 cm). They are sometimes called "pigeon hawks" due to their somewhat pigeon-like flight.
Build: Stocky body with broad chest, sharply pointed wings, and a medium-length, square-tipped tail.
Facial Markings: Unlike American Kestrels, Merlins generally **lack prominent "mustache" (malar) stripes** on their face, or if present, they are much fainter. The face is often more uniformly streaked.
Flight: Powerful, direct, and swift flight with rapid wingbeats. They rarely soar, preferring to fly with purpose.
Diet: Primarily small birds, often caught in mid-air through surprise attacks. They also eat large insects, especially dragonflies.
Nesting: Merlins do not build their own nests. They typically use old stick nests built by other birds, like crows, magpies, or other raptors, or sometimes tree cavities or even ground scrapes.

Male Merlin in Oregon
Coloration: Adult males are generally **slaty gray to dark gray** on their upperparts (back and wings). This can sometimes appear almost bluish-gray, particularly in some subspecies.
Underparts: Pale rufous to buffy, with heavy dark streaking. There can be a reddish wash along the sides of the breast.
Tail: Dark with **narrow, distinct white or pale gray bands**. There is usually a single wide black band near the tip, followed by a thin white tip.
Size: Males are noticeably smaller than females, usually about 25% lighter by weight. They typically weigh 4.5-6.6 oz (128-187 g).

Female Merlin in Oregon
Coloration: Females and immatures are generally browner overall than males, lacking the slate-gray tones.
Upperparts: Dark brown or slate-brown on the back and wings, often with some dark barring on the wings.
Underparts: Creamy to buff, with heavier, broader dark brown streaking than the male.
Tail: Dark brown with numerous narrow buff-colored or brownish bands. The banding may be less distinct than on the male's tail.
Size: Females are larger and heavier than males, a common characteristic in raptors. They typically weigh 6.4-8.3 oz (181-235 g).

Important Considerations for Oregon:
Black Merlin (Pacific Northwest subspecies): The Black Merlin, common in coastal and western Oregon, is the darkest of the subspecies. Both males and females of this subspecies tend to be more uniformly dark overall, with reduced or less distinct banding on the tail and often a darker head. Even the males might appear less "blue-gray" and more "blue-black" or very dark gray. This can make distinguishing sexes based on subtle color differences a bit more challenging, but the size difference generally remains.
Juveniles: Juvenile Merlins of both sexes resemble adult females, making them dark and streaky. This means if you see a brown Merlin, it could be an adult female or a juvenile. Size is often the best indicator for separating adult females from juvenile males.
Habitat in Oregon: Merlins in Oregon can be found in a variety of open habitats, including coastal areas (where they often hunt shorebirds), open forests, grasslands, prairies, and increasingly, urban and suburban areas where they prey on small birds like House Sparrows.