A panel of outside scientists investigated BLM’s handling of wild horses and issued a critical report in 2013 that said the bureau’s current policies are making the crisis worse.

“It is clear,” the panel from the National Academy of Sciences writes, “that the status quo of continually removing free-ranging horses and then maintaining them in long-term holding facilities, with no foreseeable end in sight, is both economically unsustainable and discordant with public expectations.”

Wild horse advocates have expressed doubt about BLM’s warnings that horses left to their own devices would starve due to too many horses on the range. However, the scientists cited case studies that bolster the BLM’s fears.

The NAS study supported birth control vaccines as the “most promising fertility control methods.” However, it noted that all birth control drugs cause physiological and behavioral side effects.

In 2013 the BLM gave birth control shots to 509 mares. The most common was a drug called PZP. Depending on the variety, it wears off after a year or two.

The scientists encouraged more use of birth control vaccines, though conceded it may not be sufficient to solve the problems, and called on the BLM to include the public in reaching its management decisions, while warning against a continuation of “business as usual practices.”

The scientists did not weigh in on whether roundups are conducted humanely.

The BLM issued a statement welcoming the report early in June of 2013. It quoted BLM Deputy Director Neil Kornze saying that the BLM shares the committee’s view that there are “no quick or easy fixes.”

Seven months later, the agency has not announced any changes in its operations in response to the scientists’ advice.