The European starling (Sturnus vulgaris) is a small perching bird that originated in Europe and parts of Asia. It was introduced to North America in the late 1800s and has since become one of the most numerous songbirds on the continent. The European starling is now found throughout most of North America, from Alaska to Mexico. In many areas, particularly in urban and agricultural environments, European starling populations have expanded dramatically. This has led some people to consider the European starling an invasive species, especially in parts of Canada like Ontario.
What is an invasive species?
An invasive species is one that is not native to a particular region or ecosystem. Invasive species are introduced, intentionally or unintentionally, by human activities. They can then spread aggressively, displacing native plants and animals. Invasive species can cause major alterations to ecosystems by changing habitat structure, disrupting food webs, and monopolizing resources. They are considered one of the greatest threats to global biodiversity.
Some key characteristics of invasive species include:
- Originate from another region, continent, or hemisphere
- Spread quickly in their new environment
- Establish rapidly expanding populations
- Lack natural predators or pathogens that would limit growth
- Cause harm to the environment, economy, or human health
In order for a non-native species to be considered invasive, it must cause some kind of harm or damage to the new ecosystem. Many non-native species do not spread aggressively or have significant impacts, so they are not classified as invasive. However, some species are able to thrive so successfully in new regions that they displace native flora and fauna, degrade habitats, or otherwise negatively affect the local ecology. These problematic non-native species are given the label “invasive.”
History of the European Starling in North America
The European starling is native to Europe, western Asia, and north Africa. It has a very wide range across these regions, inhabiting diverse habitats from woodlands to urban centers. European starlings were first introduced to North America in the 1890s. A wealthy pharmaceutical manufacturer named Eugene Schieffelin was involved in a program to introduce all the birds mentioned in the works of Shakespeare to Central Park in New York City. As part of this eccentric endeavor, Schieffelin released approximately 100 European starlings in 1890 and another 40 in 1891.
The birds soon began to multiply and spread outward from New York. By 1942, they had reached the Mississippi River and continued expanding their range westward across the continent in subsequent decades. The success of European starlings in North America stems from their ability to adapt to a variety of habitats, sustained high reproductive rates, and lack of natural predators. Currently, the North American population of European starlings is estimated at over 200 million birds. They now breed throughout almost the entirety of North America.
Ecological Impacts in Ontario
The European starling is considered an invasive species in parts of Canada, including Ontario. While starlings in Europe and Asia migrate seasonally, those in North America are mostly sedentary. They remain in breeding areas year-round, rather than migrating. This puts them in more direct competition with native bird species.
One major ecological impact is the competition starlings create for nesting cavities. Starlings nest in cavities in trees, human structures, and nest boxes. They aggressively take over cavities preferred by native cavity nesters like bluebirds, flickers, and swallows. Starlings frequently evict the rightful occupants of nest sites or even destroy their eggs. Reduction of nesting sites can negatively affect reproduction of these native species.
Starlings may also compete with native birds for food resources. Their omnivorous diet allows them to switch between fruits, grains, invertebrates, small vertebrates, and food waste provided by human activity. Starlings often forage in large, dense flocks that can displace other birds.
Additionally, starlings serve as vectors for diseases and parasites that can spread to native birds, plants, and livestock. They negatively impact agriculture by feeding on fruit crops, sprouting seeds, and contaminating livestock feed. Their droppings can spread invasive weed seeds. Starlings are also a hazard around airports because of the potential for bird strikes with aircraft.
However, the overall ecological impacts of starlings are complex. In some cases, starlings mostly utilize habitat niches and resources that native species do not fully exploit. They may fill an ecological role that was previously empty. Their effects likely depend on the composition of native species in the community and availability of resources. In general, starlings appear to have their biggest impacts on populations of cavity-nesting bird species.
Management and control
A variety of methods have been attempted to control starling populations:
- Nest boxes for native cavity-nesting birds like bluebirds can provide alternative nesting sites and help conserve their populations.
- Trapping and removing starlings, or disrupting their nests and eggs, can reduce local populations.
- Toxic chemical controls like DRC-1339 are sometimes used to poison and kill large numbers of starlings in problem areas.
- Feeding restrictions, modifications of fruit orchards, and other habitat management can make areas less hospitable to starlings.
- Falconry programs using hawks or falcons can harass and disperse starling flocks.
However, complete eradication of starlings is likely impossible over broad scales. Lethal control also raises ethical concerns and risks harming non-target species. Given the widespread establishment of starlings, management efforts usually focus on specific problem sites rather than widespread population culling. Maintaining healthy native ecosystems may be the best way to mitigate damages.
Conclusion
The European starling is considered an invasive species in parts of North America because of its rapid spread and negative ecological impacts following its introduction. In particular, competition with native cavity-nesting birds for nesting sites is a major concern. However, the starling’s effects are complex, not uniformly harmful, and mitigated in some areas. While eradication is not feasible, targeted control efforts combined with habitat management and conservation can reduce damages. The starling’s invasion highlights the unpredictable and long-lasting impacts that can arise from introducing non-native species. Going forward, responsible management will rely on ongoing research into coexistence strategies that protect native species.