Changing Wolf Populations
3:41 pm
Fri July 5, 2013

Wolves' Social Structure Means Dynamic Population Changes

Wisconsin’s gray wolf population is estimated at over 800 - high enough that the state Department of Natural Resources allows a certain number of wolves to be hunted each year.  

Wisconsin's gray wolf population has rebounded most strongly in the last 15 years.
Wisconsin's gray wolf population has rebounded most strongly in the last 15 years.
Credit Wisconsin Department of Natural Resources

But in the 1970s the wolf population was a fraction of that number, leading to their protection under federal and state legislation.  Jennifer Steinglein studies wolf population dynamics at the University of Wisconsin-Madison.  She says the recent population growth didn’t happen all at once.  Its strongest increase came within the last two decades.              

“We think over the last fifteen years in this period of high growth, wolves have been experiencing less illegal killing than in the very early years.  Maybe after a period of time, people were a little bit more accepting of wolves on the landscape, so the illegal killing rate went down.”

Early population growth may have also been hampered by something called the elite effect. 

“Individual wolves weren’t finding each other in order to create packs in order to have offspring.  And that kind of reduced the growth in the early years.  But once there’s enough wolves on the landscape, they can reproduce quite quickly.  Every year packs are probably reproducing four to six individuals.’

Stenglein notes that a conservative approach may be best when deciding how many wolves should be harvested, since wolves’ social structure complicates their population dynamics. 

“They’re a pack structure.  So if you kill an alpha female for instance, that has a very different effect on the population than if you kill a yearling that’s just dispersing and doesn’t have its breeding role.  The jury I think is still out on the effect of hunting on wolves – and especially the effect on wolves in such a human dominated landscape.” 

Steinglein is giving a talk on her research at the Kemp Natural Resources Station in Woodruff:  Monday, July 8that 7 pm.