Band-tailed Pigeons in Oregon, like in other parts of their range, exhibit very little sexual dimorphism, meaning males and females look quite similar, making them challenging to distinguish visually in the field.

General Appearance of Adult Band-tailed Pigeons (both sexes):
Size and Shape: They are large, stocky pigeons, noticeably larger and chunkier than common Rock Pigeons. They have relatively small heads, a long, rounded tail, and thick-based, pointed wings.
Coloration: Their plumage is generally a soft, overall gray.
Head and Chest: Often have a purplish-gray or purplish-pink wash.
Upperparts (back and wings): Bluish-gray.
Underparts (belly): Pale gray to nearly white.
Distinctive Markings:
White Nape Crescent/Collar: A prominent white crescent or collar on the back of the neck (nape) is a key identifying feature of adults.
Iridescent Green Neck: Just below the white crescent, the feathers on the neck have a subtle iridescent green sheen.
Tail: The namesake feature – a broad, dark band near the tip of the tail, contrasting with a paler gray tip.
Beak, Legs, and Feet: The beak is yellow with a black tip, and their legs and feet are yellow.
Eyes: Red eyes.

Subtle Differences (Males vs. Females):
While not definitive for individual identification, some general observations can be made:

Coloration: Females may appear slightly duller in color overall, with the purplish tints on the head and chest being less pronounced compared to males. The black band on the tail might also be less distinct in females.
Size/Robustness: Some sources suggest males may appear slightly more robust, with a thicker head and wider neck, and potentially a larger/wider crop area, but this is often subtle and not a reliable distinguishing factor without direct comparison.
Behavior: This is often a more reliable indicator than appearance.
Vocalization: Males are generally more vocal, known for their deep, soft, owl-like "whoot-woooo" or "who-whoo—who-whoo" calls. They also make mechanical chirping calls.
Courtship Displays: During courtship, the male will fly up and glide in a wide circle, giving a wheezing call and fluttering his wings. On a perch, the male puffs up his chest and neck, lowers and spreads his tail, while cooing to impress a female.
Nesting Roles: Both sexes participate in incubation and chick-rearing, but they often have fixed schedules. In Oregon, males typically attend nests from mid-morning until mid-afternoon, while females incubate from mid-afternoon until the following mid-morning. Males also bring twigs for nest construction, while females do most of the building.

Juvenile Band-tailed Pigeons:
Juveniles lack the distinctive white crescent and iridescent green feathers on the nape. They are generally a more uniform brownish-gray and may have white feather edges above, giving them a scaly appearance.

In summary, while there are very subtle differences in plumage vibrancy and overall robustness, the most reliable ways to differentiate male and female Band-tailed Pigeons in Oregon are through their behavior, especially during breeding season, and their distinct vocalizations.