MN DNR WMA "Survey" & Large Wolf Margin of Error

I also sent a follow-up email asking why the article headline seemed to insinuate that the rise in deer population was the sole driver for the rise in wolf population. Have yet to hear back on that...

His reply...


Good question. I'll start with a couple caveats first. 1) we can never prove cause and effect with these types of observational surveys. That requires formal experiments. So any interpretation of the data is to some extent just a hypothesis, but I like to think one based on sound logic and data. And of course, if we don't offer our hypotheses in the reports, everyone calls and asks "why did wolves increase (or decrease)", and so we offer our best assessments. 2) I always remind myself of the margin of errors on each estimate - so while the point estimates from the past 2 surveys suggest a 25% increase in wolves, the true change could be more or less than this.

So acknowledging these 2 limitations to any hypothesis here, in this case I do think 1) the wolf population has in fact increased, even if not specifically by 25%, and 2) the most parsimonious explanation for the increase is in fact nothing more than a deer increase. With increasing deer, which is the case here, wolves need less real estate now to meet their needs, territories can shrink and still support as many (or slightly more) wolves, so the landscape can accommodate more packs. Certainly there are other factors that can influence wolves, like disease, self-limitation through territoriality, winter weather (which not only affects deer numbers, but also affects wolf hunting success), human-related killing (be it legal, illegal, accidental), etc. But I would generally only consider those factors if deer were clearly increasing and wolves were not. At this time we don't have any evidence that disease is a concern limiting wolves, we have no public harvest, we do not believe depredation take or illegal/accidental killing is a concern, deer are increasing, and so I would expect wolves to be primarily responding to this changing carrying capacity on the land. And that is largely driven by deer numbers, at least up to some point where self-limitation (territoriality, etc) might start to limit wolves (e.g., if deer numbers increased to HUGE levels, it of course wouldn't translate to us having 40 wolves per 20 acres). There is a lot of data and meta-analysis that clearly shows that prey density is the best single predictor of wolf density, at least in the absence of targeted efforts to reduce wolf numbers or limit their population growth rate. The only other caveat is just that sometimes wolves may respond with a 'time-lag' to changes in deer numbers, but in relatively simple systems like we have here (1 main prey species in most areas), wolves will approximately and eventually track deer most of the time. So I'm certainly open to other interpretations and acknowledge this is best viewed as a hypothesis (not fact), but I can't now think of other more reasonable explanations for the data.

John

I do not think wolves have increased their presence, just because there are a pack of wolves in northern Anoka County would explain this. There were wolves here  before, my grandfather hunted them!