European starlings are a highly adaptable bird species, successfully established across much of the globe, including North America. Their ability to thrive in diverse environments and their generalist diet contribute significantly to their widespread presence.
The Diet of European Starlings
The diet of European starlings is notably varied, reflecting their omnivorous habits. During warmer months, they primarily consume invertebrates such as grubs, caterpillars, beetles, spiders, earthworms, centipedes, snails, and millipedes. Approximately 58% of an adult starling’s diet consists of these invertebrates.
Plant Materials in Their Diet
Beyond invertebrates, starlings also incorporate plant materials into their diet. They consume various fruits like berries, apples, pears, plums, cherries, grapes, peaches, and strawberries. Seeds, grains, nectar, and even livestock feed are also important food components. This varied diet allows them to exploit resources in diverse habitats, including urban and agricultural areas.
Seasonal Dietary Shifts
Seasonal changes significantly influence starling feeding habits. During the breeding season, their diet shifts to prioritize protein-rich invertebrates for adults and chicks. Nestlings are fed small, soft-bodied invertebrates like beetles, caterpillars, and cranefly larvae, which are easier to digest. This high-protein intake supports rapid growth.
Autumn and Winter Diet
As autumn approaches and insect populations decline, starlings transition to a diet increasingly reliant on fruits, berries, and seeds. Agricultural crops, including grains, become more prominent food sources during cooler months. During winter, when natural food sources are scarce, starlings may consume grain and household waste.
Foraging Strategies
European starlings employ distinct strategies to acquire their varied diet. They are primarily ground foragers, often seen probing lawns and other open areas with short vegetation. A unique foraging technique, “gaping” or “open-bill probing,” involves inserting their closed bill into the soil and prying it open to locate hidden grubs. This method accesses food beneath the surface.
Opportunistic Foraging
Starlings also glean insects from foliage and are opportunistic scavengers. They forage in human-modified landscapes, including parks, suburban yards, and agricultural fields. They frequently forage in large flocks, which can efficiently clear out feeding stations and exploit localized food sources.
Ecological Implications
The broad diet of European starlings has significant ecological implications. As insect predators, they can help control populations of agricultural pests like grubs and caterpillars. However, their consumption of fruits, grains, and livestock feed makes them agricultural pests, especially for crops like cherries, grapes, and apples. They can also contaminate livestock feed and water with their droppings, posing risks of disease transmission.
Impact as an Invasive Species
Their generalist diet and adaptability contribute to their success as an invasive species in many parts of the world. They outcompete native bird species for food resources, particularly during harsh winters when food is limited. Their aggressive nature also allows them to displace native cavity-nesting birds from nesting sites, impacting local avian diversity.