Dispersal in response to different reintroduction strategies

Since the reintroduction of wolves, researchers have recorded pack movements and found that wolves disperse hundreds of miles both within and outside of their territory. Wolf movement shows evidence of homing tendencies, such that wolves tend to return to the range of their natal pack. Wolf control has required the relocation of many individual wolves, or sometimes a few members of a pack, and often the wolves return back to their original territory after being moved great distances. Wolf tracking is done with the use of radio-collars. Each wolf released during the reintroduction has a collar, and by now nearly all wild wolves have been tagged, analyzed, and given a name and a number. High rates of dispersal among wolves convinced biologists that acclimation before release may be the optimal strategy of reintroduction.

In Yellowstone, wolves from Canada were put in pens near the release site for 10 weeks before being released. This was done with the belief that the wolves, once released, would not migrate great distances north, but would instead remain very close to Yellowstone. Wolf radio locations after reintroduction supported this prediction. By late June 1995, the wolves released in Idaho had on average moved 50 miles north, and the three packs released in Yellowstone had not shown any inclination to move north (Phillips and Smith, 1996). This observational study shows evidence that movement soon after reintroduction is reduced by acclimating wolves to their surrounding.

However, before being convinced by this observation, it is important to look at dispersal over a longer period of time. If wolves have true homing abilities, migration north, towards Canada, seems inevitable. Is it likely that 10 weeks in a holding pen in Wyoming will rid these wolves of their natural instinct to return to natal land? Radio-collar data should provide some sort of evidence of long term trends, and from this the optimal reintroduction method may be determined.

Given the close interface between wolves and humans, wolf control is mandatory and this has meant relocating individual wolves or even entire packs. It would be nice if "problem wolves," for example, a wolf that has killed a local rancher's calf, could be darted and relocated to an isolated wilderness area hundreds of miles away and remain there. However, control methods of relocation do not always eliminate the problem.

Alpha female, wolf B36, is one of the 66 gray wolves taken from Canada and relocated into Idaho. Since then her growing family has formed the White Cloud Pack, which is unfortunately in close proximity to humanity. B36 and her pack came down from the mountains and ate two calves, forcing relocation measures to be taken. Biologists and officials have been trying to guide B36 and her pack deeper into the mountains where they will be more protected, however radio tracking shows that these wolves keep returning to their natal territories, which also happens to be close to a few angry ranchers. A recent article in The New York Times tells the full story on wolf B36.

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