The European starling (Sturnus vulgaris) is an omnivorous bird that feeds on a wide variety of food sources. As an invasive species that has been introduced to many parts of the world, the European starling has adapted its diet to take advantage of local food availability. Understanding the dietary habits of European starlings can provide insights into their biology, ecology, and interactions with native wildlife.
Insects
Insects make up a major part of the European starling’s diet throughout the year. Starlings feed on a diverse array of insects including beetles, flies, grasshoppers, crickets, caterpillars, moths, ants, bees, and wasps. Insects are rich in protein and fat, providing an excellent source of nutrition for starlings.
During the breeding season, starlings rely heavily on insects to feed their chicks. Adults make frequent trips to gather insects including cutworms, millipedes, snails and earthworms to bring back to the nest. In one study, beetles alone accounted for over 50% of the food brought to nestlings. Caterpillars, flies, ants, and spiders were also common food items.
Insects continue to be a key part of the starling diet year round. European starlings often forage for insects in open grassy areas, fields, pastures, and lawns where insects are abundant. Their constant need for high protein insects to feed their young drives starlings to seek out productive foraging locations. Starlings sometimes gather in large flocks numbering hundreds or thousands of birds to take advantage of large concentrations of insects.
Fruit and Berries
Fruit is another important seasonal food source for European starlings. Starlings eat a variety of wild berries and fruits including mulberries, juniper berries, chokecherries, black elderberries, dogwood fruits, and pokeweed berries. They also feed on cultivated fruits from orchards and vineyards, especially grapes, peaches, plums, apples, pears, figs and olives.
Fruit provides starlings with essential vitamins, minerals, carbohydrates and sugars. Starlings rely on fruit more in fall and winter when other natural foods are scarce. Their ability to shift to fruits helps starlings maintain higher overwinter survival compared to other bird species. However, this same adaptability also allows starlings to cause significant agricultural damage when they descend on vineyards or orchards and attack ripening fruit.
Seeds and Grains
Seeds form another key component of the European starling diet. Starlings feed on a variety of seeds from wild grasses, trees, shrubs and agricultural crops. Important natural seed foods include seeds from meadow grasses, pigweed, lamb’s quarters, smartweed, ragweed, sunflowers, ash, elm, dogwood, blackberry and sumac. Starlings also readily eat cultivated grains including corn, wheat, sorghum, rice and oats.
Seeds provide rich carbohydrates for starlings. They often feed in large flocks on grain fields, stubble fields, feedlots and bird feeders to take advantage of abundant seeds. However, agricultural damage from starlings can be substantial as they consume and contaminate large quantities of livestock feed and planted grains.
Mealworms and Earthworms
Mealworms and earthworms are high-protein prey that starlings feed on heavily at times. Mealworms often become more important in the diet of nestling starlings after they fledge in early summer. Earthworms emerge on wet lawns and pastures where starlings gather to feed in large numbers. Earthworm abundance and availability influences local feeding patterns.
Mealworms and earthworms are soft-bodied invertebrates easily captured and swallowed by starlings. Their bodies are rich sources of protein and fat. Both are farm and garden pests, so starlings provide some natural pest control when they feed on these invertebrates.
Nestling Diet
Adult starlings provide a wide range of natural foods for their nestlings and fledglings including:
- Insects: beetles, caterpillars, ants, wasps, flies
- Earthworms and snails
- Berries: dogwood, pokeweed, black elderberry
- Seeds and grains
Nestling starlings need high protein foods for growth and development. Insect prey dominate the diet, accounting for over 50% of food items in most studies. But starling parents also bring back berries, seeds and other plant matter to feed chicks. The variety of foods helps ensure chicks get adequate nutrition.
As chicks grow older, parents gradually provide larger prey items. Small insects and larvae are fed to young nestlings. Larger caterpillars, grasshoppers, beetles and earthworms are brought to older chicks. This progression in prey size correlates with the chicks increasing size and energy needs.
Geographic and Seasonal Variation
The European starling’s diverse diet allows it to adapt to very different habitats across its native and introduced ranges. Some key regional and seasonal differences include:
- More fruit consumption in Mediterranean climates with extensive orchards and vineyards.
- Greater consumption of berries during fall and winter in cold northern climates when other foods are scarce.
- High use of grain in agricultural plains and cropland.
- Increased insect consumption in spring and summer during breeding season.
- More earthworms and soil invertebrates taken in wet, mild climates like England.
Starlings take advantage of any abundant, high-energy food source. Their ability to shift between insect prey, fruits, seeds, and other foods allows them to thrive across an immense range of habitats and conditions.
Foraging Behaviors
European starlings use a variety of specialized foraging behaviors and strategies to find food, including:
- Flock feeding – Starlings form large flocks that work together to locate and exploit patches of abundant food.
- Ground probing – Starlings insert their long bills into soil to probe for insects and worms under the surface.
- Fruit pecking – They peck and feed on ripening fruits still attached to trees and vines.
- Fly catching – Starlings hawk flying insects from perches and on the wing.
- Gleaning – They actively search and glean stationary prey from soil, tree bark, foliage, and other substrates.
This combination of opportunistic foraging strategies allows starlings to successfully exploit a wide diversity of food across many different environments. It contributes to their ability to spread and thrive as invasive introduced species.
Food Availability Drives Movements
The availability of key food resources often determines European starling movements and habitat use through the year. Some examples include:
- Nesting habitat is chosen based on proximity to insect-rich foraging areas.
- Flocks concentrate at farms and feedlots when grain becomes abundant in late summer and fall.
- Berry and fruit availability draws flocks to orchards and vineyards in late summer and fall.
- Abundant soil invertebrates support flocks on lawns and pastures through winter in milder climates.
Tracking the seasonal movements and habitat use of starlings reveals insights into key food items driving their behavior in different regions. This can help inform management efforts to limit damage from invasive starling populations.
Damage to Crops and Livestock Feed
The European starling’s diverse and opportunistic diet includes many economically important agricultural fruits, grains, and livestock feeds. Their large concentrated flocks and adaptability enable starlings to cause extensive damage, including:
- Consumption of cultivated grapes, peaches, berries, pears, olives, figs, and other fruits.
- Eating recently planted grain seeds and sprouting plants.
- Contamination of cattle feedlots and dairy rations. Each starling consumes around 1 ounce of feed per day.
- Spreading of diseases that affect livestock and crops through feces and bacteria.
Total economic loss to agriculture from invasive European starlings just within the United States has been conservatively estimated between $800 million to $2.2 billion per year. Identifying vulnerable crops and implementing control measures can reduce this damage.
Management and Control
Several management options exist to reduce crop damage and conflicts caused by European starlings:
- Exclusion netting over fruit crops and vineyards.
- Propane cannons, distress calls, and other scare devices to repel flocks.
- Altering feeding and water sources to be less attractive.
- Population reduction through trapping or targeted lethal control.
- Habitat modification around fields and feedlots.
An integrated wildlife management plan customized for the site and situation generally works best. Completely eliminating starling damage is difficult but an effective management plan can reduce the problem to tolerable levels in most cases.
Conclusion
The European starling owes much of its immense invasive success to its diverse and opportunistic diet. Starlings consume a wide variety of natural and agricultural foods including insects, fruits, seeds, grains, worms and more. Their ability to shift diet seasonally and take advantage of locally abundant resources allows them to thrive across an immense range of environments around the world. However, this same dietary flexibility also enables starlings to cause extensive damage to fruit and grain agriculture. Understanding the food habits and foraging ecology of the European starling continues to be important for developing more effective management solutions for this challenging invasive species.
