HELENA, Mont. - The federal agency responsible for protecting animal and plant health has agreed to improve how it responds to public-records requests after a Montana wildlife advocacy group claimed the agency regularly put off responses to Freedom of Information Act queries.

The U.S. Department of Agriculture's Animal and Plant Health Inspection Service will now provide an explanation when it claims that unusual circumstances prevent the agency from responding to FOIA requests within the statutory limits.

The agency's responses also will include a phone number or website to track requests, and its staff will be trained on responding to requests, according to the settlement agreement approved by U.S. District Judge Donald Molloy on Dec. 21.

A Montana wildlife advocacy group sued APHIS in March 2012 over delayed responses to public-records requests and a failure to turn over all requested documents related to wild bison from Yellowstone National Park.

The Buffalo Field Campaign's six requests between 2011 and 2012 involve records from APHIS programs dealing with bison disease and population control, and include tracing reports for diseased cattle in Idaho, Montana and Wyoming.

The advocacy group said in its lawsuit that the federal agency was unresponsive to its requests or used an "unusual circumstances" exception to repeatedly delay responding to requests. When the agency finally did respond, some documents were withheld, the advocacy group said.

The Freedom of Information Act requires an agency to respond to a public-records request within 20 working days. There is an exception that allows a government agency facing unusual circumstances to extend that deadline by 10 working days.

The circumstances can include the need to search for records from several offices, the need to consult among different groups or the sheer number of records requested.

The changes don't affect the entire agriculture department, only APHIS, spokeswoman Lyndsay Cole said Wednesday. The agency already is as responsive as possible to public-records requests, she said.

"This doesn't really change much," Cole said. "This lays out a few more specific things we need to do, but we will continue to be compliant" in responding to FOIA requests, Cole said.

Buffalo Field Campaign habitat coordinator Darrell Geist disagreed, saying the settlement should correct what had become a "pattern of practice" by APHIS to withhold public records. He said his group plans to test whether the agency has complied with the agreement by filing a request later this month on records related to a bull-semen study.

"We are going to put this to the test," Geist said. "Any member of the public should benefit" from the changes.