The consortium of state wildlife agencies aiming to boost the lesser prairie chicken population is downplaying an apparent decline in the species overall numbers.

A wildlife biologist with an environmental group said the decline shows a “clear need for federal protection.”

“Today, fewer of these rare birds exist in the entire world than people in Garden City, Kan.,” said Erik Molvar, wildlife biologist with WildEarth Guardians. “Habitat destruction continues, and voluntary conservation programs aren’t getting the job done; this bird needs the protections of the Endangered Species Act now.”

The latest aerial survey, conducted this spring, found just 25,261 birds in the five states they inhabit. In 2015, a similar survey found 29,162 birds.

The Western Association of Fish and Wildlife Agencies, of which Kansas is a member, said the reduced numbers “is not significantly different” from what was found a year ago.

WAFWA wildlife biologist Jim Pitman, based in Emporia, said the only statistically significant change was in the shinnery oak region of New Mexico and the Texas Panhandle.

In other locations where the bird can be found, Pitman said, the changes “could have been due solely to sampling variation in the survey methodology and not real changes in the number of birds.”

Because the aerial survey report hasn’t been made public, he was unable to provide specific changes, especially for the shortgrass prairie that encompasses northwest Kanas.

“I can say right now that the apparent decline in the shortgrass is not statistically detectable, which means it may not be real,” Pitman said in an email. “I suspect the actual number of birds on the ground is very similar to last year in the shortgrass region and the apparent decline is just a result of sampling variation associated with the survey methodology.”

The lesser prairie chicken, in recent years, has been a springboard for activity, especially after it was listed as a threatened species by the U.S. Fish and Widllife Service in early 2014. That’s when a number of lawsuits were filed challenging its listing.

Earlier this year, a federal judge in Texas refused to grant a request from FWS to let it re-evaluate the effect WAFWA’s range-wide conservation plan has had on the species recovery. The judge ruled the agency failed to consider the plan, even though it had only been OK’d just days before FWS determined the bird should be listed as a threatened species.

The federal wildlife agency opted not to appeal the judge’s ruling and let the listing lapse.

In addition to Kansas, lesser prairie chickens can be found in Colorado, New Mexico, Oklahoma and Texas.

“Wildlife biologists note prairie chicken numbers regularly fluctuate up and down from year to year due to changes in habitat conditions mainly influenced by rainfall patterns,” WAFWA said in a statement announcing the aerial survey’s findings.

“The promises of voluntary conservation plans from the states, counties and industry have proven ineffectual,” Molvar said. “This decline shows that lesser prairie chickens are not rebounding and is proof positive that Endangered Species Act protections are essential to prevent the extinction of this magnificent bird.”

Although WAFWA didn’t detail numbers for regions, it said increases were seen in southeast Colorado and southwest Kansas, as well as in New Mexico and Texas.

Those areas saw the greatest declines during 2011 and 2012.

But population decreases were seen in the mixed-grass region of northeast Texas, northwest Oklahoma and south-central Kansas, areas that have suffered in recent years.

The stronghold of shortgrass prairie in northwest Kansas — containing the greatest number of birds — also declined, the report states.

“Just as with last year’s population increase, we shouldn’t read too much into short-term fluctuations over one or two years,” said Bill Van Pelt, WAFWA grassland coordinator. “The monitoring technique used for this survey is designed to track trends, and both the three- and five-year trends still indicate a stable population.

“Lesser prairie-chickens inhabit a large geographic landscape with highly variable weather patterns, so we expect to see annual and regional population fluctuations.”

Van Pelt, however, said conservation efforts, such as those sought by WAFWA, “help to ensure that suitable habitat is available so these population increases can occur when weather conditions are suitable.”

The range-wide plan, with a goal of boosting the lesser prairie chicken population to 66,000 birds, is funded by conservation payments that let companies operating in the birds’ range to do so without worry about the effect they have on the species.

When the bird first was listed, there was a federal incentive to participate.

So far, oil and gas companies and utilities have committed more than $60 million in enrollment and mitigation fees to pay for conservation, and landowners across the range have agreed to conserve more than 130,000 acres of habitat through 10-year and permanent conservation agreements. WAFWA recently purchased a 30,000-acre ranch in southwest Kansas as part of its plan.