The European Starling (Sturnus vulgaris) is a common bird across North America, introduced in the late 19th century. Their adaptability allows them to thrive in human-altered landscapes, making their nests and eggs a frequent discovery near homes and structures. Accurate identification is important because starlings are cavity-nesting birds that aggressively compete with native species for limited nesting spaces.
Key Visual Characteristics of Starling Eggs
A European Starling egg is distinct due to its color and lack of markings. The shell exhibits a uniform pale hue, typically a very light greenish-white or bluish-green. The surface is notably smooth and possesses a slight sheen, giving it a glossy appearance. Measuring approximately 1.1 inches (2.7 cm) in length and 0.8 inches (21 mm) in width, the eggs are small to medium-sized and oval. The defining visual characteristic is the near-complete absence of speckles, spots, or other pigmentation marks.
Where and When Starlings Lay Their Eggs
Starlings are obligate cavity nesters, meaning they must find an enclosed space for their nest. Preferred sites are often near humans, including holes in trees, abandoned woodpecker cavities, and structures like eaves, vents, gutters, and streetlights. The nesting cavity is typically filled with a loose, bulky mass of materials such as grass, twigs, leaves, and sometimes trash. The breeding season begins early, starting in mid-March in southern regions and mid-April in northern areas. Females generally lay one egg per day until the clutch is complete, which typically contains four to six eggs. The presence of fresh green plants woven into the nest material is a unique habit during the egg-laying and incubation phases.
How to Differentiate Starling Eggs from Look-Alikes
Distinguishing a starling egg from those of other common cavity nesters relies on egg appearance and nest structure. The starling’s plain, pale blue or greenish egg contrasts sharply with the eggs of the House Sparrow, another non-native cavity dweller. House Sparrow eggs are typically grayish-white with numerous dark brown or gray speckles, making them easily distinguishable.
Differentiating from Native Species
Differentiating starling eggs from those of native species, such as Eastern Bluebirds, can be more challenging since both lay unmarked blue eggs. However, the bluebird egg tends to be a richer, brighter blue compared to the starling’s paler, sometimes greenish hue. The nest itself also offers a helpful clue: a bluebird nest is a neat, woven cup of fine grasses or pine needles, unlike the starling’s messy, bulky nest that often fills the entire cavity.
European Starlings are considered a non-native, invasive species in North America. They are not protected by the federal Migratory Bird Treaty Act. This information is important for those managing competition in nest boxes, as starlings aggressively displace native birds like bluebirds.