Chicago's smooth green snakes were already fading, then scientists found toxins in their eggs

Development has been reducing the prairie habitat used by Chicago's smooth greensnakes for years, helping drive the species into decline. Researchers now say the snakes may be confronting another threat even before they emerge from their eggs.

What happened?

A new study by Allison Sacerdote-Velat, the Peggy Notebaert Nature Museum's curator of biology and herpetology, found contaminated soil and fungal disease are creating additional problems for the tiny, nonvenomous reptile in the Chicago area, according to the Chicago Sun-Times.

The latest findings build on an existing concern about a species native to Illinois and the Midwestern prairies, whose habitat has been shrinking. Researchers found heavy metals in smooth greensnake eggs, including arsenic, copper, iron, and lead.

The study indicated that those metals may reach the eggs through multiple routes, with some contamination coming from the soil and some possibly being passed from mother snakes to the eggs.

"We have learned that post-industrial land use history, proximity to transportation infrastructure, and proximity to intensive agriculture exposes the remaining populations to heavy metals during a sensitive developmental period," the study said.

The researchers also documented the fungal pathogen Ophidiomyces ophiodiicola in smooth greensnakes from Cook, DuPage, and Lake counties.

The study also found that a population of the snakes was still present at a Southeast Side post-industrial site first studied in 1945, though at a lower density, and that its eggshells had higher lead levels than those from any other site in the study.

Why does it matter?

For a species already struggling to survive, the danger extends beyond disappearing habitat.

According to the Sun-Times, conservationists had, as of last year, incubated and hatched more than 2,000 smooth greensnake eggs and released snakes to bolster or reestablish populations.

The study further said that the findings could help "guide future conservation projects for the smooth greensnake" and may inform how the snake is reintroduced into certain grassy areas in the suburbs, as has been done for more than a decade, with Sacerdote-Velat a key part of that effort.

What are people saying?

Kathryn McCabe of the Lake County Forest Preserves said smooth greensnakes add to the beauty of our outdoors, saying, "Honestly, they're adorable really, super cute," the Sun-Times reported.

A petition has also been started asking officials to declare the smooth greensnakes "threatened" in Illinois, which would provide them with more legal protections, but additional data were determined to be needed.

Scott Ballard of the Illinois Department of Natural Resources put it simply: "Any time you're losing a species you're losing biodiversity." 

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