A reader of this blog, Gary Ott, wrote an excellent letter to the Methow Valley News in response to anti-wolf propaganda concerning the effect wolves would have on deer herds. The Methow Valley is home to The Lookout wolf pack. Sadly the alpha female (mother) of the pack is missing.
Gary’s letter was originally published in the Methow Valley News on May 5, 2010.
Wolves in the Methow: a predator/prey relationship
By Gary Ott
The relationship of wolves and their prey is a topic of much debate, speculation, scientific study, political expediency, misinformation and ulterior motives.
Measuring population levels of prey species is vital to understanding the principles of how wolves influence prey numbers. Although there are several systematic methods utilized by wildlife biologists to estimate populations of deer, elk or other prey species, obtaining numbers that accurately represent populations across landscapes proportional to the movements of deer and elk is problematic at best.
Aerial infrared photography and other new technological tools are being used and developed in other places, but as yet, there is no simple and conclusive answer to accurately assessing general population levels of deer and elk in absolute numerical terms. It is especially difficult in complex terrain of mixed open and forested land. With commonly used methods it is easier to estimate whether a population is increasing or decreasing; and the ratios of males to females, and females to young. This is not to say that reasonable estimates of population levels cannot be made, but that the difficulties involved limit the certainty of the results.
Cause-and-effect relationships are even more elusive. If wolf populations are increasing and prey populations are declining, it does not necessarily follow that one is the cause of the other. Winter severity, multiple prey and predator species, hunting, trapping, poaching (of both predator and prey species), disease, precipitation, the availability of browse, and other habitat conditions, contribute to the complexity of the problem of trying to separate and weigh the proportional effect of predation by wolves from other factors. If this is not complicated enough, the conclusions made from studies of one place may not be transferable to other landscapes, climates and ecosystems.
On the other hand (or in spite of this reality), anti-wolf advocates in Western states make extraordinary claims; not only of knowledge of both wolf and prey populations but also of the cause-and-effect relationship between the two. Casual observations cannot accurately assess populations of deer and elk herds that respond to a wide range of factors that influence, not only their population level, but also their movements across landscapes that are disproportionate to the experience of an individual. And yet, logical sounding conclusions of cause-and-effect relationships are defended as if they are proven fact and not the result of assumptions based on insufficient information, and a biased perspective. Contrary to the statements of anti-wolf factions, the re-establishment of wolves (and their population increase) in Western states has coincided with prey population levels that have, in some places increased, while in others areas deer and elk numbers have decreased or remained fairly stable.
Wolves are very keen at recognizing prey individuals that are most vulnerable due to disease or other physical infirmities. Wolves’ preferential selection of these animals can be beneficial to the health of the herd in several ways. The overall fitness of the herd can be more important to its long-term well being than the number of individuals that comprise it.
Wolves sometimes kill more prey than they immediately consume. Excess predation is commonly described as wasteful and accounted for by attributing it to a moral depravity that more appropriately applies to human aberrant behavior and not the behavior of animals. While we cannot know why excess predation occurs, it appears to be a reflex reaction to prey behavior or occurs in the confusion of a pack attack on a herd. Although we may not understand the driving force behind excess predation, it may serve more than one purpose. Wolves commonly compete with bears, wolverines and other predators for prey. Excess predation may reduce the chance of a conflict with a bear or other predator over a single carcass. Wolves also remember and return to feed on carcasses (that may be preserved by freezing) hours, days, or sometimes months later.
Uncertainty is not in the realm of opinionated points of view, but some degree of uncertainty is a realistic standpoint for those who are interested in understanding the possible future of wolves and their prey in the Methow Valley. Reproductive families of wolves have been in the North Cascades and here in the Methow Valley before –as recently as the early 1990s. What happened to them? Will the Lookout Mountain pack also mysteriously disappear or will their offspring and/or other immigrant wolves form additional packs? How many packs can the Methow Valley support and what effect might they have upon the deer population?
There are some facts that are fairly consistent among many studies that may be of use to better understand the possibilities. Average pack size in the northern tier Western states is six or seven individuals. Pack territories can be expected to average around 300 square miles (the Lookout Mountain pack fits this model at about 350 square miles). This would suggest that four or five packs (maximum) could potentially exist in the Methow area.
Studies of predation on deer in other states indicate that per wolf, approximately 15 or 16 deer are taken per year. This level of predation is on a scale that is nearly the number that we take out with our cars, not even close to the numbers taken by hunters, and a much smaller fraction of the numbers that snow conditions and winter severity can account for.
But of course, this is still assuming that wolves survive, reproduce and remain here.
Gary D. Ott lives near Beaver Creek.
Posted in: gray wolf/canis lupus
Tags: Methow Valley, predator/prey relationship, Look Out Pack