European Starling, Sturnus vulgaris
European Starlings, despite their considerable beauty, tend to be unpopular with birders; they are an introduced (non-native) species whose massive presence in North America stems from releases of only about 100 birds in New York in the 1890s. They aggressively compete with native cavity nesters, including especially the beloved bluebird species.
The two images above show European Starlings in fresh fall plumage following their only molt of the year. The light spots wear off throughout fall and winter so that by spring breeding season, when the bill turns yellow, the underpart plumage is smooth and the iridescence of the glossy black feathers is more striking, as shown in the two pictures below.
Above, a starling in January, with some of the light underparts markings worn off, and the bill partly yellow; below, at the end of
February, with most of the white marks worn off and the bill almost completely yellow.
A starling in April showing breeding plumage, with nesting material.
An adult starling at the entrance to its cavity nest in June.
A juvenile European Starling, probably recently fledged, in June.
A flock of juveniles in the midst of their first molt at the end of July, showing varying extent of adult-like light-spotted glossy black feathers on underparts, wings, and tail, while still retaining brown juvenal plumage on their backs and heads. European Starlings are "highly social birds, preferring to feed, roost, and migrate in flocks at all times of the year. Pairs readily breed away from others, but will also nest in close proximity to others if breeding sites are available." (Birds of North America Online)