WASHINGTON (AP) — Wondering who is visiting the White House? The web-based search has gone dark. Curious about climate change? Some government sites have been softened or taken down. Worried about racial discrimination in housing? Laws have been introduced to bar federal mapping of such disparities.

Since taking office, the Trump administration has made a series of moves that have alarmed groups with a stake in public access to information — historians, librarians, journalists, climate scientists, internet activists, to name a few. Some are so concerned they have thrown themselves into “data rescue” sessions nationwide, where they spend their weekends downloading and archiving federal databases they fear could soon be taken down or obscured.

Previous presidential transitions have triggered fears about access to government data, but not on this scope.

“What is unprecedented is the scale of networking and connectivity of groups working on this, and the degree it is being driven by librarians and scientists and professors,” said Alex Howard, deputy director of the Sunlight Foundation, a group that tracks transparency in government.

The White House declined to comment, but Trump’s supporters say the administration’s detractors are overreacting. Trump is committed to open government, said Ben Marchi, a Trump supporter and Republican operative. In a recent interview with McClatchy, Marchi noted how, prior to announcing the selection of Neil Gorsuch to serve on the Supreme Court, the White House released a list of 21 candidates under consideration.

Yet moves by the Trump administration have helped stoke the fears. In February, the U.S. Department of Agriculture removed animal cruelty data from its website, prompting protests from animal welfare advocates, including the Humane Society, which has filed a lawsuit against the USDA.

Also in February, the Trump administration suspended an Obama regulation aimed at protecting whistleblowers who work for Department of Energy contractors. The regulation would have permitted civil penalties against contractors that retaliate against whistleblowers. Supporters of the rule say that its rescission will make it harder for contract workers at the government nuclear facilities to report waste, abuse and safety concerns.

Trump, Howard said, has made clear he will seek to prosecute leakers and has labeled the media an “enemy of the people.” He has dismissed climate change science and raised questions about the use of vaccines.

“The reaction we are seeing is driven by concerns unique to this administration,” Howard said.

During his eight years in office, President Barack Obama was hardly a darling of open government advocates. His Justice Department prosecuted nine cases against whistleblowers and leakers, compared to three by all other previous administrations.

But Obama also took some steps to increase transparency, including establishing a web-based log of visitors to the White House. That log allowed journalists and others to track lobbying at the White House, including links between the Obama administration and the pharmaceutical industry.

But easy access to the log disappeared after Trump was sworn in. The National Archives and Records Administration stopped paying a contractor to maintain an embedded web application for the Obama-era visitation records. They are still available at the Obama White House archive, but only on zip files that are difficult to download and analyze.

As of last week, the Trump administration had not built a web page with information about recent visitors to the White House, although it has said it will post such records “on an ongoing basis, once they become available.”

Other information of interest has also disappeared. The phone book for employees at the U.S. Department of Energy has been removed from the agency’s website. Several federal websites have been altered to eliminate or tone down evidence linking human activities to global climate change.

While all incoming administrations put their ideological stamp on federal websites, librarians and other professionals fear that previously accessible raw data could be put behind walls. They have started networking on how to salvage what they can.

Bethany Wiggin, founding director of the environmental humanities program at the University of Pennsylvania, and others started organizing dozens of “data rescue” sessions nationwide, in which activists were invited to bring their laptops and ideas for federal data sets deemed vulnerable.

Fearing that federal data on gun violence might also vanish under a president with close ties to the National Rifle Association, Dr. Garen Wintemute called together his partners in the Violence Prevention Research Program at the University of California, Davis.

Within minutes, the team was downloading a crime victimization survey from the Bureau of Justice Statistics. They scoured the Bureau of Alcohol, Tobacco and Firearms, gathering data on retail gun sales. They preserved mortality records from the Centers for Disease Control and Prevention, which includes a field for deaths caused by firearms.

“I don’t think the CDC would do that of their own volition, but they might be directed to,” said Wintemute, an emergency room doctor. The data sets are now stored on a secure server at UC Davis.

Access to existing federal records is one concern of data rescuers. The other is whether the government will continue to collect information as it has in the past. Earlier this year, for example, a group of Republicans that included U.S. Sen Mike Lee of Utah, Sen. Marco Rubio of Florida and U.S. Rep. Paul Gosar of Arizona introduced legislation to undo a 2015 Obama regulation aimed at reducing past patterns of housing segregation.

How Trump may approach access to federal data is not entirely known, but one upcoming appointment will provide a signal. In coming weeks, the administration will appoint a director to the Office of Information and Regulatory Affairs, which it is charged with guiding federal policy on information technology, information policy, privacy and statistics.

“That is going to be a key position in the federal collection of data going forward,” said Raphael Calel, an assistant professor of public policy at Georgetown University.