By John Burch
Wolf 258 was an impressive wanderer. In early May 2011, this male wolf left Yukon-Charley Rivers National Preserve, Alaska, and headed out on a 2,000-mile (3,219-kilometer) journey over seven months through northeastern Alaska and western Yukon Territory, Canada. But this wolf's journey was not unique. Probably hundreds of wolves every year throughout wolf range take similar trips. What was unusual about 258's journey was that he was wearing a GPS collar, allowing us to track his movements almost daily.
We captured 258 on November 5, 2010, via helicopter darting in Yukon-Charley as a part of long-term monitoring of the preserve's wolf population that began in 1993. We captured him because he was paired with Female 227, a wolf we had followed via telemetry since 2007. The female had bred in the Edwards Creek pack for at least two years. However her pack had dwindled to nothing, so for the past two years 227 had traveled alone most of the time in her home range. She had briefly paired one other time, but that association did not last long. After 227 finally paired again in August 2010, we captured her mate and numbered him 258. He was a 103-pound (46.72-kilogram), 2-year-old male in excellent condition. The pair had traveled widely throughout its home range for a few months before 227 died (probably of starvation) in February 2011. Wolf 258 continued to travel alone throughout the pair's home range but then left to begin his long journey.
Dispersing wolves take a risk when they leave their natal pack. Resident packs are territorial and often kill intruders. Thus a dispersing wolf, especially one that covers hundreds of miles, must travel a gauntlet through the territories of many other packs.
Whenever either a male or female wolf disperses, it is looking for a new place to live and for a mate. If dispersing wolves of the opposite sex meet and find an area unoccupied by resident wolves, they breed, produce pups and start a new pack assuming there is enough prey in the area. Sometimes a dispersing wolf can be accepted into an existing pack as a breeder, replacing a former breeder that died. An uncommon scenario is that a dispersing wolf is accepted into an intact existing pack. Exactly how this all transpires between individual wolves we don't know. However, wolves' sense of smell is at least 13 times greater than that of humans, and possibly a dispersing wolf can tell from urine marks that the resident pack lacks a breeding wolf of the same sex. The bottom line: Dispersing is risky but worth it if successful.
We use two types of radio collars to track wolf movements. The first is a conventional radio collar that has been used for decades. It transmits a pulsing signal that must be tracked from an airplane equipped with a receiver and antennas to locate the wolf.
The second, a Global Positioning System (GPS) collar, is one we have used on wolves in Yukon-Charley beginning in 2003; this is the type 258 was wearing. These collars can be tracked from aircraft like the others, but the big difference is that GPS collars also collect a location every day and transmit it via satellite to the biologist's email.
Many wolves disperse each year. Some travel hundreds of miles while others end up in an adjacent home range. With 258's dispersal, we could follow his route because of his GPS collar. In the end, 258's luck ran out. A necropsy of his carcass confirmed that he starved to death -a risk many dispersing wolves take.
Source: Burch, J. 2011. Annual report on vital signs monitoring of wolf (Canis lupus) distribution and abundance in Yukon-Charley Rivers National Preserve, Central Alaska Network: 2011 report. Natural Resource Technical Report NPS/CAKN/NRTR-2011/485. National Park Service, Fort Collins, Colorado. A download of the full report is available at: https://irma.nps.gov/App/Reference/DownloadDigitalFile?code=434746&file=YuchWolvesNetworkMonitoring2011AnnualReport.pdf.
John Burch is a wildlife biologist for the National Park Service and has studied wolves in Alaska for 25 years.