Mexican Gray Wolf Census: The Cost of a Count

On February 18th  U.S. Fish and Wildlife Service (FWS) announced the results of its Mexican gray wolf census—the annual count of the endangered wolves living in the wild.  The number, 97, is down from last year’s 110.

 Photo Credit: Mark Dumont via Compfight cc

Photo Credit: Mark Dumont via Compfight cc

Each January FWS conducts its survey from the cockpits of an airplane and a helicopter. It’s the best time of year to count  wolves—they are easier to spot in the snow and their population is at its most stable, pups born the prior spring are almost grown and are running with the adults.

As part of the survey a few of the wolves are darted from the helicopter and are transported to a mobile clinic to be examined and outfitted with radio collars. In this Arizona Daily Sun story, “Anatomy of a Wolf Count,” the reporter walks us through the capture and release process.  It usually goes smoothly and within a few hours the wolf is back on its home turf.  But this year two female wolves suffered complications and died after being captured, sad news any time, but especially in a year when the population decreased significantly.  Because the count is “as of the end of the year,” both wolves are included in the total.

One of the wolves, F1340, died within minutes of being darted.  She was a three-year-old born into the Bluestem Pack in 2013, captured and collared during last year’s census without incident.

Tracking her history through monthly status reports, I discovered that F1340 began to travel away from her pack about this time last year and was spotted by the field team with a male wearing a non-functioning radio collar.  In the spring it appeared she might be expecting pups based on signals transmitted from her radio collar, indicating she was staying in one area, not traveling, probably digging a den.

By mid-summer the field team reported seeing the two adults with five pups.  The new wolf family was named the Marble Pack.  They established a territory in the northwest-central portion of the Apache-Sitgreaves National Forests in the White Mountains of Arizona.

In August the field team captured and collared one of the pups, a male, and assigned him studbook number mp1440.  The next month they captured a female pup and gave her number fp1442.  Their father, the alpha male of the pack, remained unidentified.

In what should have been a routine capture operation on January 28th, the field team darted both alphas and one of the pups of the Marble Pack.  As reported above the alpha female, F1340, died quickly and unexpectedly (a necropsy conducted at FWS’ forensics lab may provide more answers about the cause of her death).  The pup, fp1442, was checked for a foot injury and released.  The alpha male, identified as M1243*, formerly of the Paradise Pack, was re-collared and released.

The Marble Pack, now incomplete without its alpha female, may or may not have stayed together.

February is breeding season for Mexican wolves (they mate only once per year).  There is no way of knowing how it might have turned out, but if F1340 had survived she might now be preparing a den for a new litter.  It’s likely the yearling pups would have continued to travel with M1243, hunting, bringing food to F1340, continuing to mature—preparing to disperse, find mates, establish territories.

Even without the alpha female it’s impossible to predict the fate of the Marble Pack.   These wolves, born and raised in the wild, are resilient.  I’ve followed F1340’s original pack, the Bluestems, for years and time after time the family of wolves has survived shootings, wildfire, challenges from other wolves, encounters with livestock and humans, and probably countless other things not revealed by a radio collar or field observation.

For now all we can do is hope.


*According to the Mexican Wolf Recovery Program Reports #14, #15 and #16 (years 2011, 2012, and 2013, respectively) M1243 was born to the Paradise Pack in 2011.  He left his natal pack late in 2012. When his collar stopped transmitting in 2013, he was considered “fate unknown.”

To find FWS press releases, monthly monitoring reports, and annual progress reports go to The Mexican Wolf Recovery Program.  For more information and ideas for ways to take action on behalf of the wolves go to

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