Tuesday, July 15, 2014

Unlearned: "The Lesson of the Kaibab"

Article: Shrinking deer population in West spurs new push for answers, action

There is a classic lab used in Biology classes called "The Lesson of the Kaibab."  It is an historical look at the numbers of mule deer on the Kaibab Plateau of Colorado. The lab has been criticized for a number of reasons: especially the lab's assumptions and deer numbers.

A short version is that in 1904, President Theodore Roosevelt intervened on behalf of the "finest deer herd in America." Predators and hunting were eliminated and grazing permits for cattle and sheep were withdrawn.

The deer population exploded, rising to 3X the carrying capacity, then crashing. The plateau itself was overgrazed, causing its own problems.

[Carrying capacity: the population size of an organism that its environment can support on a sustained basis.]

I try to lead the students to the idea that sometimes it is better to leave well enough alone. That is, at any rate, what I take away from "The Lesson of the Kaibab."

It would appear that the reporter and the politicians know nothing of the history of the Kaibab deer experience; and that is natural enough. On the other hand, it is obvious that the various "spokesmen" for ecological organizations and federal bureaus are just as ignorant.

They acknowledge that a major part of the problem is the harsh winters (no global warming?) that have been frequent lately.

However, the "action" they propose are exactly and precisely the same proposed in 1904 for the Kaibab Plateau deer population.

The major predators (the wolves) are all still, mostly, gone. They want to reduce hunting, as before. They want to eliminate grazing, as before.

They slam "oil and gas development" as if it is a magic and evil wand. The mule deer live in the largest ecosystem, the sage brush, in the west and "oil and gas development" is a major threat?  Really, consuming 10's of thousand of acres? Driving the deer to extinction? Sorry, not reasonable.

One spokesman notes the problems caused by invading white-tailed deer. There is no mention of the problems caused by wild horse and donkey populations. These are non-native, invasive species that are also very competitive. But wild horses are "mustangs" and to many people they are seen as something romantic, rather than the large "rats" they actually are. (If you are being ecologically correct.)

The biggest risk to the mule deer of the west is overreaction.

The carrying capacity of the range has been decreased due to the weather of the last few years. It will recover.

It is also common and natural for the number of grazing animals to rise and fall. And, if the studies on rabbits are any indication, there does not seem to be any driving, exterior cause to it. 

Classically, we teach that rising and falling numbers havr to do with predator-prey relations. However, that does not appear to be true with the rabbits, nor is it true with moose/wolf populations.

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