The administration determined in September that destroying habitat where endangered or threatened species breed, feed or take shelter would no longer trigger federal penalties. An internal memo also signals plans to interpret the law as prohibiting only intentional killing of endangered animals, rather than also covering actions such as harassing, harming, trapping or capturing them.

Illinois has 24 federally endangered species and 12 listed as threatened. Nearly two dozen state attorneys general have sued over some of the federal changes.

The proposed shift could particularly affect species that are hard to see or depend on vulnerable habitats. The rusty patched bumble bee, for example, spends about half the year in soil, making it difficult to detect before construction or other development damages its habitat.

The bee was once common across 28 states, including Illinois, and parts of Canada. Its population has fallen nearly 90% over the past three decades, and it now occupies about 0.1% of its historic range. It became the first bee species federally listed as endangered in 2017.

“I personally only saw one,” said Libby Shafer, an urban ecologist and Northwestern University doctoral candidate, describing a three-month effort to find the bee across Illinois, Indiana and Wisconsin. She warned that the federal changes are bad news for the species.

Piping plovers, small migratory shorebirds, also depend on fragile habitat. A pair known as Monty and Rose nested at Montrose Beach from 2019 to 2021, marking the first time the birds had nested on Chicago beaches since at least 1948. The birds compete with recreation and development for beach and coastal areas.

Great Lakes piping plovers have shown signs of recovery after their regional breeding population fell to about a dozen pairs in the 1990s. At a recent high point, close to 800 pairs were nesting across the region. But urban ecologist Mikko Jimenez cautioned that recovery remains uncertain if habitat safeguards are weakened.

Freshwater mussels face a similar threat. They account for half of Illinois’ federally endangered wildlife, and the state’s rivers once supported about 80 mussel species before the number fell to 59 by around 1970. Water pollution, habitat degradation and invasive species are among the pressures on the animals. Industrial agriculture has also altered freshwater habitats and connections between rivers across Illinois and the Midwest.

“The full impact of these regulatory changes remains uncertain,” said Kentaro Inoue, a research biologist at Shedd Aquarium. Protecting endangered mussels, he said, requires protecting the river systems they depend on, not just the animals themselves.

Elizabeth Forsyth, a senior attorney with Earthjustice’s biodiversity defense program, said the combined changes could remove habitat protections and automatic safeguards for threatened species while increasing industry’s influence over decisions. The consequences could reach beyond wildlife: for Illinois communities, the health of beaches, pollinator habitat and river systems is closely tied to the ecosystems these species need to survive.