23 February 2026

Starlings (European starlings, Sturnus vulgaris) are the invasive species Americans love to hate. They’ve only been on this continent for 136 years, having been successfully introduced in 1890 & 1891 in Central Park, New York. DNA studies indicate that every starling in the U.S. is descended from the Central Park group.

Have our starlings physically changed since they got here? Have they evolved differently from their native relatives in Eurasia?

In 2023 a team led by Julia M. Zichello(*) set out to answer that question. They measured 1,217 starlings including their beaks, wings and tarsi (plural of tarsus) using historical museum skins and modern birds from the U.S. and Eurasia, especially starlings in the UK.

Tarsus length can serve as proxy for bird body size.

Their study found that U.S. starlings have indeed changed from their Eurasian relatives:

Beak length in the native range has remained unchanged during the past 206 years, but we find beak length in North American birds is now 8% longer than birds from the native range. … Additionally, body size in North American starlings is smaller than those from the native range.

— Recent beak evolution in North American starlings after invasion, Julia M. Zichello et al, Nature.com

Graphs from the study show the differences in orange (U.S. starlings) and blue (native-range starlings).

• U.S. birds have longer beaks (top graph and histogram).
• Both native and U.S. birds have become smaller over time (bottom graphs) but the U.S. birds are overall smaller.

Why did U.S. starlings make these changes?

Smaller size: A lot of reasons

The study says, “Smaller birds in North America, versus larger birds in the parent population, occurred rapidly on arrival and this trend has persisted today,” perhaps because (a) U.S. birds experience warmer summer temperatures than the native range (warmth makes organisms trend smaller), (b) starlings experienced “genetic drift” upon arrival, and/or (c) the founder population of birds (the 1890-91 group) may have randomly consisted of smaller bodied birds.

Longer beaks: Livestock grain vs. natural food

Longer beaks were the big revelation in this study and they conclude that it has to do with diet. U.S. starlings eat a lot of grain at cattle feedlots in winter (longer beaks are an advantage). Eurasian starlings don’t.

The most dramatic difference between starling diet in the U.S. and their native range is the intensity of their foraging at dairies and feedlots in the U.S., where they consume substantial amounts of food intended for livestock.

Since 1960, corn production in the U.S. has increased exponentially, which has also enabled a concurrent expansion of the cattle industry. By the 1960’s feedlot operators in several states were reporting major starling disturbance. In our data, 1960 is when we observe a marked increase in proximal starling beak length in the U.S. beyond what is observed in the native range at any time.

Starling flocks on U.S. dairies can exceed 10,000 birds and cause an estimated $800 million dollars of annual
lost revenue across the country. … We estimate that starlings may consume [136 million lbs] of livestock feed per year in the United States. An individual bird can eat up to 2.2 lbs (1 kg) of feed per month, and 1,000 birds can consume 630 lbs (286 kg) every hour spent foraging at feedlots.

— Recent beak evolution in North American starlings after invasion, Julia M. Zichello et al, Nature.com

Yikes!

Traveling the PA Turnpike in fall and winter my husband and I often remarked on the “starling barn,” a dairy farm near Plainfield with a HUGE flock of starlings that always caught our eye as we passed. This winter the starlings were not noticeable, perhaps because USDA “helped” the farmers with their starling problem. Listen to The Controversy Over Controlled Poisoning Of Starlings from WBUR in January 2017. It’s an interview with Bob Mulvihill of the National Aviary.