POOR SCIENCE EVIDENT IN UTAHS SPRING BEAR HUNT
By Sharon Emerson
The design chosen for Utah's spring bear hunt violates the basic tenet of a scientific experiment. This poorly conceived study will do little to address the two basic questions it was set out to answer: whether a spring bear hunt can reduce the percentage of harvested females and decrease the level of depredation.
A spring bear hunt persists in only a handful of states. They have been banned in most areas because, inevitably, when a lactating female bear is killed during the spring hunt, her orphaned cubs also perish. Additionally some question whether killing bears as they emerge from a known wintering area can rightfully be considered a sport.
The spring bear hunt was suspended in Utah in 1993. However, pro-spring hunting groups have never given up. Since 1993, Utah statewide bear harvest records have shown an undesirable increase in the percentage of female kills as well as elevated killing of livestock (= depredation), predominantly by male bears. These pro-hunting groups have used that data to argue for a resumption of the spring bear hunt. Their contention is that because male bears usually emerge from their dens before the females, an early spring hunt would result in easier identification of sex by the hunter and the killing of more males. They argue this should lower the percentage of females killed and at the same time, lower the incidence of depredation since most nuisance bears are males.
In 2000 the Utah Division of Wildlife Resources decided to offer an experimental spring bear hunt to test this argument. The idea was to compare sex ratios of harvested bears and level of depredation among bear management units where hunting occurred at different times of the year. Management units with spring-only hunts would be compared to those that only
In science, the key feature of experimentation is control of most factors that might influence a result. In that way, the importance of those few factors that do vary can be seen more clearly and assigned more reliably as a cause for differences between groups. In the spring bear hunt experiment the major factor that is varied or being examined is time of the hunt. Accordingly it is important to minimize any other variation that might occur between the two groups to be compared. Unfortunately the spring bear hunt experiment has failed to do this in many significant ways. Below I will give three examples where variation was actually added to the experiment rather than eliminated.
First, in the first year of the experiment mandatory orientation sessions were held to educate hunters in the spring hunt how to distinguish male from female bears. In contrast, no such workshops were required for the fall group of hunters. This difference in preparation for the hunt clearly could lead to a bias in the number of females killed in the spring. Spring hunters might kill fewer females not because they were easier to identify in spring but rather because the fall hunters lacking the mandatory orientation class were less well prepared to distinguish male and female bears.
Second, the length of the spring hunt was changed in the middle of the experiment. The first year of the experiment, 2001, the spring bear hunt ran for four weeks from April 14th through May 13th. In 2002, the spring bear hunt was extended for two additional weeks. This moved the hunt into a time when even more females were present. Additionally, in the second year of the experiment, changes were made in the number of hunting permits issued for some management units. Clearly the length of the hunt as well as the number of issued permits can influence the number of bears that will be harvested. Changing hunt time and permit number between years, once the experiment is underway, introduces another level of undesirable variation into the experiment.
Finally, as mentioned above, six management units were chosen for the experiment. Each spring hunt unit was matched with its own specific fall hunt unit for data analysis. In theory, spring and fall units were paired because they shared similar characteristics such as geographic location in the state, hunting pressure, level of depredation, and hunting success rate.
Unfortunately, there are problems with pairing these units. In two out of the three pairs the fall hunt units experience twice the potential hunting pressure as the spring units. Similarly, in two of the three pairs, the spring hunt units show a higher hunting success rate than the paired fall units. Finally with all three pairs there is a considerable difference in the amount of pursuit hunting (hounds chasing bears into trees) pressure between the spring and fall units.
In conclusion, the spring bear hunt experiment is deeply flawed. Any conclusions at the end of the five years will not be based on reliable scientific evidence. A more basic question, however, is whether science, even well done, can address the question of a spring bear hunt. My answer to that would
(HUPC Board Member Sharon Emerson is a Research
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