Eurasian collared doves are an invasive bird species that have rapidly expanded their range across Europe, Asia, and North America over the past century. Originally native to Asia and Europe, Eurasian collared doves were accidentally introduced to the Bahamas in the 1970s and quickly spread across the Caribbean. Since then, they have been sighted in nearly every U.S. state, as well as Mexico and Canada. Eurasian collared doves thrive in human-altered landscapes and have adapted well to urban and suburban areas. Their global invasion has sparked concern due to their potential impacts on native species and ecosystems.
What Are Eurasian Collared Doves?
Eurasian collared doves (Streptopelia decaocto) are medium-sized doves measuring approximately 12 inches (30 cm) long with a gray body, black collar around the neck, and white tail feathers with a black terminal band. Their scientific name comes from the Latin streptopelia, meaning “collar dove,” and decaocto, referring to the 18 tail feathers present in most individuals.
Eurasian collared doves are primarily ground foragers and their diet consists mainly of seeds, grains, and human food scraps. Unlike many native doves, Eurasian collared doves are not migratory and maintain permanent territories year-round.
One key factor allowing Eurasian collared doves to thrive is that they are highly adaptable. They nest on artificial structures and can produce up to six clutches per year with two eggs per clutch on average. Combined with the lack of native predators in their invasive range, their reproductive output allows them to increase rapidly in number once established.
Native Range and Introduction Timeline
Eurasian collared doves are native to Europe and Asia, with their original range spanning from the Balkan Peninsula to China. Populations in Japan and across southeast Asia are also considered native.
Here is a timeline of their introduction and invasion across continents:
Year | Location |
---|---|
1930s | Collared doves expand range in Europe due to warmer temperatures and availability of food sources in urban areas |
1974 | A pet bird breeder accidentally releases several Eurasian collared doves in Nassau, Bahamas. A breeding population quickly establishes. |
1982 | Eurasian collared doves observed in Florida, indicating their spread from the Bahamas to the United States. |
1988 | Doves reach the Florida panhandle and continue to migrate across Gulf states. |
1997 | Rapid northward expansion begins in U.S. Populations reach Colorado, Nebraska, Wisconsin, and other northern states. |
2003 | Eurasian collared doves detected in southern Ontario, Canada, marking their arrival in a new country. |
2015 | Doves now found in nearly every U.S. state and most Canadian provinces. Population in North America estimated at over 14 million birds. |
As of 2022, Eurasian collared doves have been observed in over 6,000 localities across North America, indicating an extremely rapid and successful invasion over just a few decades. Their adaptability to urban areas has facilitated this rapid expansion.
Distribution and Abundance
Today, Eurasian collared doves are abundant across the southern and central United States as well as Mexico. Their range extends as far north as Alaska and all Canadian provinces.
Population densities are highest in the Southwest and southern Great Plains:
State/Province | Estimated Abundance |
---|---|
Texas | Over 2 million |
Oklahoma | Over 500,000 |
Kansas | Over 500,000 |
New Mexico | Over 300,000 |
Arizona | Over 200,000 |
Urban centers like Phoenix and Albuquerque have some of the highest densities, with over 100 birds per square kilometer in city parks and neighborhoods.
In the Pacific Northwest and northern tier states, Eurasian collared dove numbers are generally lower but increasing annually. The harshest winters limit their distributions in Canada and Alaska.
Impacts on Native Species
The presence of such high numbers of Eurasian collared doves raises concerns about their effects on native North American bird populations. Several potential negative impacts have been proposed:
Competition for Nest Sites
Since collared doves often nest in artificial structures, they may compete with native birds like mourning doves, pigeons, and swifts for limited nesting cavities in urban areas. Collared doves begin breeding earlier in spring than mourning doves, possibly displacing the native birds from ideal sites first.
However, some studies suggest they may provide additional nesting platforms that benefit urban species overall. More research is needed to clarify the degree of competition.
Food Resource Competition
With diets concentrated on seeds from agricultural crops, Eurasian collared doves likely overlap significantly with mourning doves and other seedeaters. In areas with high Eurasian collared dove density, increased competition for food sources could potentially reduce survival or reproduction of native birds.
However, mourning doves remain common and widespread across North America despite the collared dove invasion. Again, the degree of impact is unclear without further study.
Disease Transmission
When invasive species mingle with natives, they create opportunity for new parasite and disease transmission. Eurasian collared doves could introduce foreign pathogens to North America capable of harming native doves and pigeons. However, significant disease transmission has not been documented yet.
Researchers recommend continued disease monitoring and testing of collared dove carcasses for harmful pathogens. The dove’s association with livestock facilities elevates their potential to spread diseases of concern for poultry like Salmonella.
Ecosystem Impacts
Beyond direct competition, exceptionally high numbers of collared doves may disrupt ecosystem balances in unknown ways. Scientists suggest their abundant droppings could reduce plant diversity and soil health in areas where they congregate.
As an introduced mesopredator, they may also impact populations of invertebrates and small reptiles through excessive predation. Overall ecosystem-scale impacts remain hypothetical but deserve further study.
Positive Impacts
While concerns exist about detrimental effects, Eurasian collared doves provide some benefits where they have colonized:
Prey Resource
Collared doves augment the prey base available to native predators, including falcons, hawks, and mammalian carnivores. Their abundance may benefit urban raptor populations and improve breeding success.
Weed Seed Control
The dove’s diet includes many agricultural weed seeds that farmers often consider pests. Their foraging may provide biocontrol and reduce dependence on herbicides.
Ecosystem Engineering
Nesting collared doves break down branches and create nesting debris that other species may use. Their droppings can also fertilize soils. These types of physical ecosystem changes mimic some lost functions of now-extinct passenger pigeons.
Aesthetic Value
Many people enjoy seeing and feeding collared doves in their neighborhoods, despite their invasive status. They provide aesthetic pleasure, a connection to nature, and fun wildlife viewing opportunities for the public.
Management Strategies
Given Eurasian collared doves’ extremely rapid spread, complete eradication from North America is likely impossible. Wildlife agencies have employed various management techniques to control spread and reduce impacts:
Population Reduction
Hunting of collared doves is allowed in most U.S. states during the mourning dove hunting season. Relaxing hunting limits and encouraging harvest may help slow population growth and spread. However, their high reproductive rate makes hunting an imperfect control method.
Exclusion and Repellents
Netting over fruit crops, bird spikes on structures, and chemical repellents may discourage collared doves from utilizing some resources. However, these techniques are often prohibitively expensive or difficult to implement across large areas.
Habitat Modification
Reducing food availability around livestock facilities and grain storage silos could make some areas less attractive to collared doves. But their flexible habitat use limits this strategy.
Research and Monitoring
Continued research on nesting phenology, competition with native species, disease prevalence, and ecosystem impacts is needed to better understand dove invasion biology and inform management. Expanding citizen science reporting networks can supplement research.
Conclusion
Eurasian collared doves represent one of the most rapid and extensive avian invasions globally. While some detrimental impacts are likely, their flexibility provides benefits in certain contexts like urban areas. With complete eradication impossible, targeted management informed by research offers the best path forward to balance costs and benefits of sharing our ecosystems with these tenacious new neighbors. Their future expansion across the Americas deserves close monitoring.