The European Starling (Sturnus vulgaris) is a common and highly adaptable bird. Originally native to Europe and parts of Asia, this species was introduced to North America in the late 19th century and is now one of the most numerous birds on the continent. Their success is due to their flexibility in diet and habitat, allowing them to thrive in both rural and dense urban environments. The timing of their nesting activities is a distinct annual event, directly tied to seasonal changes and resource availability.
The Primary Nesting Window
The overall nesting period for the European Starling typically spans from early spring through mid-summer across North America and temperate Europe. Initial breeding activities often begin as early as mid-March in the southern parts of their range. The window extends through July, with the most concentrated period of egg-laying occurring in April and May. This timing is highly dependent on local climate conditions and the availability of insect food sources.
The full breeding season is extended by the species’ tendency to raise multiple clutches in a single year, a behavior known as double-brooding. Starlings that successfully raise an early brood, often initiated in April, commonly begin a second reproductive cycle in June. This second nesting attempt helps maximize the number of young produced. Females in northern regions, or those that start their first nest late, are more likely to have only a single brood.
Site Selection and Nest Construction
Starlings are classified as obligate cavity nesters, meaning they require an enclosed space to build their nests. They do not excavate their own holes, instead relying on natural tree cavities, abandoned woodpecker holes, or man-made structures. This preference leads them to utilize crevices in buildings, utility poles, under eaves, and even dryer or exhaust vents in human dwellings. They are aggressive competitors for these sites, often displacing native cavity-nesting species.
The male starling often initiates the process by selecting a suitable cavity and beginning construction to attract a mate. The nest itself is untidy, consisting of coarse materials like dry grass, twigs, and pine needles. Once a female chooses the site, she assists in finishing the structure, particularly lining the central cup. This inner lining is softer and often includes feathers, moss, fine bark, and fresh green plant material, which may serve to deter parasites.
The Reproductive Cycle
Once the nest is ready, the female begins the reproductive cycle by laying a clutch of four to six eggs. The eggs are a glossy, pale blue or greenish color, similar in size to a robin’s egg. The female usually lays one egg each day until the clutch is complete, and full incubation begins once the second-to-last egg is laid.
Both parents share the responsibility of incubating the eggs, a process that lasts approximately 12 days. After the eggs hatch, the young enter the nestling period, remaining entirely dependent on the adults for food. This period of rapid growth and development within the cavity lasts for about 21 to 23 days before the young are ready to leave the nest.