European starling an aggressive, alien species in U.S., Iowa

'I'll have a starling shall be taught to speak / Nothing but "Mortimer."'

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Mumurating starlings near Voas Nature Area seem almost to block the sunlight in their numerous flocks.


There were hundreds of starlings sitting on the electrical wires high above the road at the Voas Nature Area near Minburn this week, and I have seen huge flocks of them forming in several places across the state this fall.

In past years, ornithologists estimated some groups to number in the tens of thousands. European Starlings are one of Iowa’s and the U.S.’s most common birds. Some scientists estimate their population to be more than 200 million birds.

In fall and winter, they can be seen joining with red-winged blackbirds, grackles and brown-headed cowbirds. They fly in large flocks with no apparent leader. Their formation will look like a dark cloud bending and weaving through the sky as each bird works to move into the center of the group for protection. This type of aerial movement is called a mumuration.

European starling
European starling

European Starlings are not native to the U.S. About 100 of them were released in New York City’s Central Park in 1890 by Eugene Schieffdin. He said he wanted to “enrich” the bird life in the city by having every species referred to in William Shakespeare’s plays live in Central Park.

By 1950 the birds had spread across the U.S. and ranged from Canada to Mexico. They were first spotted in Iowa in 1922 near Lamoni, and by the 1930s thousands had spread across the state.

The starlings have been very successful due to their adaptability, hardiness and aggressive behavior. A pair of starlings will have two broods of young per year, with six babies each time. They will drive other birds away from feeders and evict them from nesting cavities. They have been observed removing eggs from a woodpecker’s nest and then taking over the site.

Probably the species most affected by the starlings’ aggression is the eastern bluebird. Bluebirds used to be very common in Iowa towns in the 1800s but when the starlings arrived, the bluebirds were chased out of nesting places and the alien birds took over.

Starlings congregate in towns, and they roost in barns and houses. They eat grain in feed lots. They are a noisy nuisance and in some cases their droppings are considered a health hazard.

In 1936 the citizens of Butler County, Iowa, were so angry at the starlings they placed a 10-cent bounty on each of these pesky birds. Thousands of them were killed, but no change in the population could be seen, and it was costing the county more money than planned. The bounty on starlings was dropped after six months.

Birders have also given up trying to kill them off and have reluctantly accepted them as part of Iowa’s wildlife scene.

An immature starling in autumn has a tan head and light-brown body.
An immature starling in autumn has a tan head and gray-brown body.

Starlings are basically black with white spots, and in the sunlight their feathers give an iridescent greenish sheen. At this time of year, young immature birds have a light-colored tan head and a gray-brown body. They are a stocky-looking bird, with a short, square tail.

They have a long, powerful, yellow beak that turns dark in fall. It is used to probe the soil in search of worms and grubs. In early spring, they can be seen feeding on lawns, looking for food.

Sometimes they are beneficial to humans by eating harmful insect pests. Ornithologists estimate their diet is 42 percent insects. The rest of their diet is composed of fruits and berries. They can do serious damage to crops, such as cherries and strawberries.

In 1915 the noted ornithologist Edward Howe Forbush warned in his writings that these alien birds were going to cause environmental problems, a warning that was not heeded at the time, and now it is too late. European starlings are here to stay.

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