The European Starling (Sturnus vulgaris) is recognizable by its iridescent black plumage, often speckled with white during winter. Introduced to North America in the late 19th century, this highly adaptable bird is now one of the continent’s most abundant species and is widespread across its native Eurasian range. Starlings are known for their gregarious nature, often gathering in large flocks that can number in the thousands. Understanding where these populations spend the colder months reveals a complex picture of flexibility and survival tailored to local conditions.
Do All Starlings Migrate?
The movement of starlings in winter is not a simple, uniform migration but is instead characterized by partial or facultative migration. The decision to move depends on the bird’s breeding location and the severity of the winter climate. Populations breeding in the far northern parts of their range, such as Scandinavia and northeastern Europe, are obligate short-distance migrants, compelled to move southwest to escape frozen ground and scarce food.
Birds in milder regions, particularly those in western and southern Europe or the southern parts of North America, are more likely to be year-round residents. These sedentary populations have enough resources to survive the winter without the energy expenditure required for long-distance travel. Migration, when it occurs, is a response to the lack of available food, such as soil invertebrates, and the onset of harsh weather.
Migration distances vary greatly. European starlings from central Europe generally head toward Spain, the Mediterranean, and North Africa, covering significant distances. Conversely, many birds from the northern United States and Canada move only as far south as the central or southern states. This mixed strategy means that resident starlings are often joined by thousands of migratory birds, swelling the local population during the winter season.
Preferred Winter Destinations
Once starlings settle into their winter range, they prefer environments offering a reliable food supply and sheltered roosting sites. Wintering locations fall into two categories: large, urbanized areas and specific agricultural or coastal regions. Cities and towns are attractive due to anthropogenic food sources, such as landfills, waste products, and livestock feed operations.
Urban areas also provide increased warmth from buildings and ample structures for safe, communal roosting. Roosts are often found in dense trees within city parks, on building ledges, or beneath bridges. In rural settings, starlings congregate in coastal areas or farmlands where they forage on leftover crops, seeds, or berries.
Specific agricultural sites, such as concentrated animal feeding operations, become major daytime foraging grounds for large flocks. Starlings often travel up to 10 kilometers between these feeding grounds and their communal nighttime roost. The choice of a winter destination is a practical calculation based on the highest concentration of shelter and accessible calories.
Survival Strategies in the Cold Months
The starling’s ability to thrive in winter is linked to its omnivorous diet and highly social behavior, which reduces individual risk and conserves energy. In summer, the diet relies heavily on insects and invertebrates, which become inaccessible once the ground freezes. To compensate, the birds shift their focus to consuming a variety of plant matter, including wild berries, seeds, and grains.
This dietary flexibility allows them to subsist on a predominantly vegetarian diet, though they exploit household waste and livestock feed when natural foods are scarce. Physiologically, starlings increase their body mass by as much as 15 grams in winter to build fat reserves, which are burned off during cold nights. They also fluff their feathers to trap warm air, providing an insulating layer against the cold.
The most striking winter survival tactic is the formation of massive communal roosts, which can contain up to a million birds. These gatherings provide shared body heat, allowing individuals to survive temperatures that would be fatal if they roosted alone.
Just before settling into these roosts at dusk, starlings engage in synchronized aerial displays known as murmurations. These dense, swirling movements are primarily a defense mechanism, making it difficult for predators like peregrine falcons to target a single bird. Murmurations also serve a social function, potentially sharing information about the best foraging locations before settling in for the night.