European starlings, scientific name Sturnus vulgaris, are small black birds with glossy feathers that are covered in tiny white spots during winter months. They are native to Europe but were introduced to New York’s Central Park in 1890 when around 100 birds were released. Their population exploded and today European starlings can be found across North America in large numbers. But are these abundant birds a good or bad addition to local ecosystems? There are arguments on both sides.
Where did European starlings come from originally?
European starlings are native to Europe and parts of Asia. Their original range stretched from Great Britain and Portugal in the west, through Europe, and east to the Ural Mountains in Russia. They thrive in open landscapes like farmland, grasslands, parks, and gardens.
How did European starlings get to North America?
In 1890, approximately 100 European starlings were released in New York City’s Central Park. A group called the American Acclimatization Society wanted to introduce every bird species mentioned in Shakespeare’s works to North America. Starlings received a prominent mention in Shakespeare’s works, including Henry IV Part 1.
The starlings thrived and spread quickly across the continent. Today they can be found from Alaska and Canada down through the United States, Mexico, and into Central America. Their range spans over 5 million square miles.
How quickly did European starling populations grow in North America?
European starlings reproduced very successfully after their introduction to New York City. Here’s a timeline of how their population boomed over the decades:
Year | Population Estimate |
---|---|
1900 | 100 birds |
1920 | 7 million birds |
1940 | 70 million birds |
1960 | 150 million birds |
1980 | 200 million birds |
As the table shows, European starling populations grew exponentially after their introduction, from the original 100 birds to over 200 million by the 1980s. They found ideal conditions to thrive in North America.
What makes European starlings so successful in North America?
European starlings possess several traits and behaviors that allow them to prosper on the continent:
- They are very aggressive and competitive for resources like food and nesting sites.
- They reproduce quickly, with females laying 5-8 eggs per clutch and up to three clutches per year.
- They nest in cavities in trees, human structures like bridges, and nest boxes, giving them abundant options.
- They form large flocks of thousands or even millions of birds that work cooperatively to find food and roosting sites.
- They eat a wide variety of foods including insects, grains, berries, bird eggs, and even trash from human sources.
- They are resilient in a variety of climates from northern forests down to tropical regions.
With high reproduction rates, broad diets, cooperative flocking behavior, and nesting flexibility, European starlings discovered an ecological niche in North America they could exploit to great success.
What effect have European starlings had on North American native species?
The explosion of European starlings across North America has had detrimental effects on many native bird species. Starlings compete aggressively for food and nesting locations, reducing resources available for other birds. Their impacts include:
- Taking over nest cavities preferred by native bluebirds, woodpeckers, swallows, and owls, reducing their potential nesting sites.
- Raiding nests of other cavity nesting birds and destroying eggs and killing nestlings.
- Displacing native bird species like woodpeckers, martins, and flickers from their natural nesting sites.
- Competing for food sources like fruit crops and reducing food available to native birds.
- Potentially spreading disease to native bird populations.
Research has quantified some of the effects. For example, one study in Arizona showed areas with starlings had 50% fewer nesting sites available for native cavity nesting birds. Bluebirds and other species can suffer greatly reduced reproductive success in areas with high starling populations.
Effects on native bluebird populations
Bluebirds are a native North American species that has declined in parts of its range since European starling introductions. This is because:
- Starlings directly compete with bluebirds for nesting cavities in trees and nest boxes put up to help bluebird populations.
- Starlings are more aggressive than bluebirds, easily outcompeting them for limited nest sites.
- Starlings will even kill adult bluebirds and destroy their eggs in an attempt to take over a nesting cavity.
Studies in Tennessee have found that areas with large starling populations can have 70% less bluebirds than areas without starlings. Providing more nest boxes does not solve the problem since starlings simply take over and dominate most of these additional nest sites.
Do European starlings provide any benefits?
While European starlings cause problems for many native bird species, they do provide some ecological services and benefits:
- European starlings eat large numbers of insect pests that can damage crops. Their large flocks can help control pest outbreaks.
- Their year-round presence provides food for predators like hawks and owls especially during fall and winter.
- Birdwatchers enjoy spotting their large winter flocks called “murmurations” that feature beautiful aerial display patterns.
However, researchers argue most of these benefits are relatively minor compared to the significant negative effects starlings have on native bird populations across North America. The services they provide are generally ones that native bird species could provide in the absence of starlings.
What methods can be used to control European starling populations?
Because European starlings are so abundant across North America and cause damage to agriculture and harm native bird populations, controlling their numbers is desirable. Here are some methods used:
Nest control
Since starlings nest in cavities, preventing them from accessing these sites reduces their reproduction:
- Block potential nesting cavities in human structures like bridges, attics, and barn rafters using metal guards, wire mesh, or other barriers.
- Use entrance holes on nest boxes that are sized for native birds like bluebirds but too small for starlings to enter and take over.
- Remove starling nests wherever they are found to prevent them from successfully raising young.
Auditory and visual deterrents
Starlings can be deterred from areas using devices that produce sounds or flashes of light that scare them away:
- Install distress call and predator call audio systems that warn starlings away and deter them from roosting.
- Use visual deterrents like reflective tape, inflatable snakes and balloons, and flashing lights to frighten starlings from fields and structures.
- Use lasers or recorded bird alarm calls triggered by motion sensors when starlings are detected.
Toxic perches
Specialized perches containing a mild toxic chemical (fenthion) are placed where starlings roost. The birds absorb the toxin through their feet which can reduce populations:
- Use only where non-target birds won’t be affected.
- Apply during winter when native birds are less active and starling numbers are concentrated.
- A single application can reduce roosting starling numbers by up to 75% for the season.
Trapping
Both small cage traps and larger drop-in traps can be used to capture starlings. The birds can then be humanely euthanized. Trapping is very labor intensive for the numbers removed but can help in sensitive locations.
Toxic baiting
Special toxic baits like DRC-1339 are formulated just for starlings and spread where large flocks gather to feed. However, this method poses risks to non-target birds and mammals:
- It should only be applied by trained personnel from the USDA Wildlife Services program.
- Bait must be kept away from areas used by domestic animals, pets, and desirable wildlife.
Should attempts be made to eliminate European starlings from North America?
While starlings cause economic damage and harm native bird populations, completely eliminating them is likely impossible. Starlings are far too widespread and numerous to feasibly eradicate at this point. Even aggressive population control campaigns only put a dent in local starling numbers. Some argue starlings are here to stay as a naturalized species in North America.
However, many researchers argue continued control efforts are worthwhile to protect agriculture and help threatened native bird species. They recommend an integrated approach combining nest site management, deterrents, limited trapping, and toxic baits to reduce starling populations to more manageable levels in priority areas. This can open ecological niches for native birds to reoccupy.
Complete eradication may be impossible across the entire continent. But through persistent control methods, starling populations can potentially be kept in check and their negative impacts reduced. Care must be taken though to avoid methods that could also threaten valued native bird and wildlife populations.
Conclusion
European starlings are abundant birds across North America that were introduced intentionally but spread rapidly and had negative consequences. Competing with native cavity nesting birds like bluebirds and taking over many nest sites, starlings have caused declines in populations of native bird species. Their large foraging flocks also damage agricultural crops.
However, starlings do provide some beneficial services like insect control. While complete elimination of starlings seems impossible now, targeted control methods can reduce their numbers in sensitive locations. This may allow native bird populations to rebound while keeping starling numbers in check. Ongoing research and adaptation will be required to find the right balance of control techniques that suppress starling populations without excessive harm to other wildlife.