The Trump administration has quietly withdrawn dozens of pending actions to protect endangered species ranging from the green sea turtle to plants in the Florida Everglades, something conservationists say may violate federal law requiring the government to act.

The pending rules were mostly withdrawn in March and April. But environmental groups and others didn't know about the action because the administration only noted it in passing in a broader posting from the White House on the status of regulations.

The U.S. Fish and Wildlife Service, which oversees U.S. policy on plants and animals in danger of extinction, withdrew a total of at least 42 pending regulatory actions pertaining to endangered species, many of which detailed how to protect animals or plants already deemed to be in peril, according to Office of Management and Budget data compiled by Bloomberg.

The Center for Biological Diversity, which has filed multiple lawsuits against the government seeking stronger protections for endangered species, wasn't aware the rules were withdrawn until asked about it by Bloomberg, said Noah Greenwald, who directs the group's efforts on the issue.

"They are required by law to issue these," Greenwald said. "If they are taking them off the schedule, they are in violation of the law and they are also putting species at risk of extinction. I think it's totally unacceptable."

The Fish and Wildlife Service took the action because it "reflects our anticipated workflow at this time," according to an emailed statement from its parent agency, the Department of Interior. The department is assessing possible additional actions on the endangered species list, according to the statement.

"Withdrawing a rule simply means the agency is focusing its resources on other priorities for the coming 12-month period," it said in the statement.

In comments last July, OMB Director Mick Mulvaney characterized the more than 400 pending rules withdrawn by the administration as the beginning of President Donald Trump's effort to cut regulations, which he views as a burden on business that slows hiring and imposes economic costs on the nation. He said they were part of a pool "that we got rid of."

The Fish and Wildlife Service's withdrawn endangered species regulations, along with hundreds of other pending rules at other agencies, were included in the OMB's so-called Unified Agenda, the twice-a-year listing of all pending regulatory actions released in July. The Fish and Wildlife Service didn't issue a press release on its decision or notify groups that had an interest in the issues.

Such notice isn't required if work is halted on a pending regulation, the agency said.

Shelving the actions on endangered species is a reversal of the agency's plans for the year. In a "workplan" posted on its website, the Fish and Wildlife Service said it would complete many of the pending regulations it halted.

Rules to protect endangered species have been controversial, frequently plagued by delays and subject to litigation. Pro-development groups, including oil drillers and home builders, have charged that the Endangered Species Act unnecessarily puts a stranglehold on economic development.

Sen. John Barrasso, R-Wyo., who chairs the Environment and Public Works Committee, is shepherding legislation to overhaul the act. "I think the Endangered Species Act has really been hijacked in ways that doesn't focus on the species," Barrasso said.

One of the withdrawn rules, which would have protected two rare garter snakes in Arizona, illustrates what's at stake and the potential legal pitfalls for Fish and Wildlife Service.

In 2014, the agency found that the snakes were endangered. U.S. law requires that a second regulatory action be taken within one year that identifies the areas that are home to the species so it can be protected, it said in the Federal Register.

But the habitat area was never completed under the previous administration of President Barack Obama. Now, with the pending rule being withdrawn, it will be delayed for at least another year.

In its workplan, the agency said it had planned to finalize 20 such habitats this year. They include protections for endangered sea turtles, bats, salamanders and fish. Sixteen of them were withdrawn this year, the records show.

"It is troubling to see the administration withdrawing scores of regulations that are required by law with little to no justification," said Amit Narang, regulatory policy advocate for the consumer advocacy group Public Citizen. "It adds to a pattern we're seeing of this administration taking legally dubious actions in order to fast-track deregulation."

- With assistance from Ari Natter