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Mexican wolf biography #10, Estrella, F521:

Happy Birthday to the Oldest Lobo Matriarch In the Wild!

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One of Estrella's grandpups (foreground), and his father, Fox Mountain AM1038 (background), caught by a remote camera in 2008. Photo courtesy of USFWS.

Mexican wolf Estrella, known officially as F521, turned thirteen today (May 3, 2010), becoming the oldest known wolf in the wild in the history of the reintroduction program.

Estrella was born on May 3, 1997, in the shadow of Pike’s Peak, at the Cheyenne Mountain Zoo in Colorado Springs. Her father was a pure McBride lineage wolf (one of the three lineages of Mexican wolves in captivity), while her mother was of pure Ghost Ranch lineage.

In 1999 Estrella was transferred to the pre-release facility at Sevilleta National Wildlife Refuge, where she was paired with M507, an offspring of Paquito (See Lobo Bio #4)  and Chamisa of the Mule Pack. The pair produced a litter of pups in 2000 and another litter in 2002. On June 11, 2002, project personnel placed Estrella, M507 (now designated as alpha male, or AM507), two wolves from the 2000 litter, and five pups of the year into a mesh pen in Arizona. The pack chewed their way out the same day. They were given the name Bluestem Pack after the native bluestem grass common in the area.

Although the Bluestem pack was involved in two cattle depredations and killed a domestic dog during that first summer in the wild, by the end of the year they had returned to killing elk. The pack has had relatively little conflict with livestock over the years, which has undoubtedly contributed to their success.

The Bluestem pack prospered, producing litters of pups in 2003, 2004, 2005, and 2006. The 2006 litter was born after the death of nine-year-old AM507 from unknown causes. After the death of AM507 in June, Estrella raised her pups with the help of several offspring from previous years that remained with the pack.

In December 2006, Laredo (See Lobo Bio #8) moved into Bluestem territory, becoming alpha male of the pack by the end of the year. According to the project annual report, Estrella, at the advanced age of ten, produced another litter of pups in 2007. It was to be her last litter. In 2008 she produced no pups. In mid-February 2009 she began traveling separately from the rest of the pack. She traveled alone for several months, but in June, aerial telemetry flights located her with the Fox Mountain Pack in New Mexico.

Fox Mountain alpha male AM1038 had lost his mate, alpha female AF1111, to a poacher in June 2008. AF1111 was one of Estrella’s daughters from her 2006 litter. AM1038 was left to raise their three pups—Estrella’s grandpups—alone. Now Estrella had joined the pack, which consisted of AM1038 and the three yearling males. Sadly, telemetry flights have failed to locate AM1038 and one of the yearlings since mid-December 2009. Estrella and her remaining grandpups, now two years old, remained together as of the April 27, 2010, telemetry flight.

Estrella has made an indelible mark on the reintroduced population of Mexican wolves. Her offspring lead four packs: Dark Canyon (AM992 from her 2003 litter); Paradise (AF1056 from her 2005 litter); Hawk’s Nest (AF1110 from her 2006 litter), and Bluestem itself (AF1042, also from her 2006 litter). Such reproductive success has its downside, however. When her pups or grandpups look for mates, it is difficult for them to find wolves of the opposite sex to whom they are not closely related. Too much inbreeding can result in decreased fitness—known as “inbreeding depression.”

If we could grant Estrella a birthday wish that would be of great benefit to her grandpups, as well as to the reintroduction program as a whole, it would be to encourage the U. S. Fish and Wildlife Service to release as many lobos as possible that are not closely related to the Bluestem wolves, and do it as quickly as possible.

Happy Birthday, Estrella!