I guess it’s only human nature to complain about the things we don’t understand.

People are forever besmirching weather men, but if they had even the slightest understanding of meteorology and nonlinear dynamics, they’d realize how remarkably accurate those guys are in predicting the weather.

They criticize Jonathan Papelbon for throwing a ball low and outside, when in all likelihood that was his precise intent on that particular pitch.

And they pick apart wildlife biologists when they fail to get their deer.

Wildlife management is an inexact, albeit very complex discipline. Because it is so poorly understood by the average nimrod, it is sometimes described as a black box, a place where, in the dark of night, they conjure up all sorts of unimaginable schemes, each designed to frustrate the license-buying public.

Well, for all you long-standing skeptics, those with above average curiosity or those merely looking for enlightenment, I’m about to expose some of what’s inside the box.

Deer probably provide the best example, because they get the most attention, both from users and managers. Every year the Maine Department of Inland Fisheries and Wildlife (IFW) biologists generate an estimate of the state’s whitetail population. They also posit what the final deer kill will be. Both numbers, it would seem, require a certain amount of smoke and mirrors to predict, or a black box.

Critics are quick to point out, “They can’t possibly know how many deer are out there.” After all, the woods of Maine are vast, thick and in many cases, remote. “There’s no way they can count them all,” the naysayers say.

The truth is, they can’t. They don’t need to. They do need a rough idea of how many deer actually live on the land, which is why it’s called an estimate. And in most cases, it’s a pretty good one, thanks to their black box.

Let’s start with the first number, the overall population. Biologists generate population estimates based on a sample, in much the same way as economists and pollsters. They sample a proportion of the population. This provides an index, which they can then extrapolate to the whole population.

For example, if you ask 10 people what their favorite color is and four say “blue,” you can predict that 40 out of 100, and 400 out of 1,000 will answer similarly, assuming all things are equal throughout the population.

But biologists don’t even have a direct index of the population, such as how many deer there are in a particular town, county or wildlife management district. They need to generate one in some other way.

What they do have, contained within their black box, is roughly 25 years worth of deer harvest data under fairly consistent seasons, regulations and bag limits. The number of hunters, the level of hunting pressure and success rates do not change considerably from one year to the next, though there are gradual shifts over several years.

Deer hunting success during the 2009 regular firearms season was around 11 percent (relatively poor on a nationwide scale). Firearms hunters who possessed an any-deer permit had an average 34 percent success rate while those restricted to bucks only averaged a 15 percent success rate.

We also know, based on license sales, about how many hunters will head afield each fall (that too is an estimate, based on another index). Multiply the expected number of hunters by their typical success rate and you get an estimate of the deer kill.

Those numbers can also help us get at an estimate of the overall population. Here, the inside of our black box gets a little a little darker. Biologists use population models, based on decades of research from across the country. They can input variables like success rates and harvest numbers, and include the number, age and sex of all deer killed. Out comes a number.

Sometimes it takes a little tweaking, but as years of data accumulate, the results become more accurate and reliable.

Let’s switch over to bears to illustrate that point, and go back roughly 15 years. From existing data at the time, IFW biologists estimated the bear population, as well as the level of hunting mortality that population could withstand and still remain stable — around 3,000.

When the kill reached or exceeded 3,000 for two consecutive years, there was some initial concern it might result in a decline in bear numbers. When the kill continued to rise, biologists took a closer look at the age structure of bears in the harvest.

An unexpectedly high proportion of younger bears indicated that not only was the population not being harmed by the existing level of hunting, it was actually growing. They had underestimated the statewide bear population. They were able to go back and adjust their overall population estimate.

Do the biologists know exactly how many bears or deer are out there on the landscape? No. And they’ll tell you so. They have a rough idea, which is the best they can be expected to do.

Sportsmen tend to dwell much more on these types of numbers.

In the final analysis, the total population size is not so important, so long as hunting, predation and other forms of mortality aren’t preventing the population growth or stability prescribed by biologists.

Bob Humphrey is a freelance writer, registered Maine Guide and a certified wildlife biologist who provides consultation to private landowners interested in improving wildlife habitat. He can be contacted at:

[email protected]


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