The number of Mexican wolves in the wild declined last year to 97 from 110 the previous year, according to an annual census of the critically endangered wolf.

The Endangered Wolf Center in Eureka, Missouri, has been instrumental in saving the Mexican wolf from extinction. At one time, only five Mexican wolves existed in the wild. When those five were captured between 1977 and 1980 and brought into managed care, the species was declared extinct in the wild. The first release of wolves from managed care facilities took place in March 1998. Nine of the 11 wolves in that release were from the Endangered Wolf Center.

A year-end population survey is conducted annually by the Mexican Wolf Interagency Field Team (IFT) and the results are announced by the U.S. Fish and Wildlife Service (USFWS), which oversees the recovery program.

The decline to 97 wolves follows five straight years of growing numbers. The survey found 42 in 2009, down from 52 the previous year. Since then the population had grown every year: 50 in 2010, 58 in 2011, 75 in 2012, 83 in 2013 and 110 in 2014.

In its news release Thursday, the USFWS attributed the decline in 2015 to a combination of factors:
·There were 13 Mexican wolf mortalities compared to 11 in 2014. Of these 13 mortalities, nine were females and four were males.
·Eleven additional wolves are considered fate unknown compared to three in 2014.
·A significantly lower proportion of pups survived to December, relative to last year: 55 percent survival in 2015 compared to high 86 percent in 2014.

In its news release, the USFWS explained how the survey is conducted:

The annual population number is derived from on-the-ground surveys conducted by the IFT from November through December of 2015, as well as from an aerial survey conducted in January and February 2016. The number is considered a minimum number of Mexican wolves known to exist in the wild in Arizona and New Mexico, as other Mexican wolves may be present. The Mexican wolf mortalities are under investigation by the USFWS’ Office of Law Enforcement in an effort to determine cause of death.

Sixteen Mexican wolves, including three breeding pairs, live at the Endangered Wolf Center. Last year, three pups were born at the Center. About 300 Mexican wolves are in managed care facilities in the United States and Mexico.

Mexican wolves are the smallest, southernmost and most genetically distinct subspecies of gray wolf. Mexican wolves were native to Mexico, New Mexico, Arizona and Texas. The recovery program releases them in New Mexico and Arizona and Mexico.

The Endangered Wolf Center also houses eight red wolves, another critically endangered species of wolf involved in a USFWS recovery program. Their release area is limited to North Carolina.

Red wolves once roamed from Pennsylvania into Missouri, down to Texas and throughout the southwest.

The Endangered Wolf Center was founded in 1971 by Marlin Perkins, the longtime host of TV’s “Mutual of Omaha’s Wild Kingdom” and director of the Saint Louis Zoo, and his wife Carol. They recognized that wolves everywhere were in danger of going extinct.

The Center is located on the grounds of Washington University’s Tyson Research Center in Eureka, about 20 miles southwest of St. Louis.