European Starlings are a common sight in Oregon, having been introduced to North America in the late 19th century. While both sexes share many general characteristics, there are subtle differences, particularly during the breeding season.

General Characteristics (Both Sexes
Size and Shape: They are stocky, blackbird-sized birds with short tails, triangular wings, and long, pointed bills. In flight, their pointed wings can make them resemble small, four-pointed stars
Plumage:
Breeding Plumage (Spring/Summer): Adults are mostly glossy black with iridescent purple and green sheens, especially on the head and body. Their plumage is relatively smooth and less spotted during this time. The bill is bright yellow.
Non-breeding Plumage (Fall/Winter): After molting in the fall, starlings acquire new feathers with white tips, giving them a heavily speckled appearance. As the season progresses, these white tips wear off, revealing the glossy, dark plumage underneath by spring. The bill is duller, often blackish.
Behavior: Starlings are highly social birds, often gathering in immense, noisy flocks, especially in fall and winter. They forage mostly on the ground in open areas like lawns and fields, probing the soil with their bills for insects. They are known for their varied vocalizations, including mimicry of other bird calls.
Diet: They are omnivores, eating a wide variety of insects, berries, fruits, and seeds.

Distinguishing Male and Female European Starlings:
While the visual differences between male and female European Starlings are subtle, especially from a distance, the most reliable distinction is the color of the bill base during the breeding season:
Males: In breeding season (spring and early summer), the base of the male's lower mandible (the lower part of the bill) is pale blue.
Females: During the breeding season, the base of the female's lower mandible is pinkish.

Other Potential (but less reliable) Differences:
Throat Iridescence (requires specific light and close observation): Recent research suggests that the iridescent throat of the male appears different from the female when seen in ultraviolet light, which birds can perceive. This is not visible to the human eye.
Bill Color Change Progression: While both sexes have yellow bills during breeding season and darker bills at other times, some studies suggest males may show yellowing in their bills slightly earlier in the season than females. However, bill color alone is not a definitive indicator of age or sex.
Behavioral Cues: During the breeding season, males establish territories and choose nest sites, often singing to attract a mate. They may bring plants to the nest cavity. Both parents participate in incubation and feeding the young.