Geist vrs Lee Rue III on Bergmann's rule…

[wildschwein]

#7307

I have been doing a bit of ready lately, mostly about Whitetails. Two books in particular stood out, “Whitetail Tracks” by Valerius Geist and “Way of the Whitetail” by Leonard Lee Rue III.

Both books were great reads and very informative. And for the most part both authors seemed to be of the same opinion on most things. One thing they did not agree on was the validity of Bergmann’s rule in relation to Whitetail Deer.

Bergmann’s rule (for those here who might be unfamiliar with it) pretty much states that the further north an animal lives, the larger its body size will be. The theory is that larger animals, having a lower surface area to volume ratio, will radiate less body heat per unit of mass, thereby staying warmer in colder climates. Members of the same species living in warmer climates have to do the opposite. They need to dissipate body heat instead of store it. So the higher surface area-to-volume ratio of smaller animals in warmer climates results in quicker heat loss and helps cool the body.

Now this theory on the surface at least makes sense. Take for example the average Whitetail buck in northern Alberta. An average weight for these animals is around about 160 to 250 pounds. Compare that to the Florida Key Whitetail buck, which averages only about 60 to 110 pounds.

In his book “Way of the Whitetail” Leonard Lee Rue III champions Bergmann’s rule (or at least he did for the edition of his book that I purchased). Valerius Geist does not however. In his book “Whitetail Tracks” he puts forward the idea that the reason for the Whitetails increased size in northern populations, is due to the higher nutritional value of their feed and lower population density. He also believes that given a few generations, a smaller subspecies of Whitetail would significantly increase its body size if given enough high quality feed, while remaining in its original habitat and vice-versa (at least that’s how it sounded to me).

Now both theories make sense to me. I was just wondering what you folks might think? Is it either or, or a combination of both?

[skifrk]

#60367

I think a combination of both is correct if you keep low population density then the deer will get bigger, as far as thicker body’s, I always thought the northern deer were that way to hold onto to more fat reserves to get through long cold stretches of winter. You would think that if an area had high nutritional value and all other factors being equal the deer would overpopulate and compete for browse leading to smaller deer. That is just my opinion.

[Stephen Graf]

#60657

I think the nutritional argument is maybe a stretch. I don’t think it is reasonable to assume that the farther south you go, the less nutritious the browse is. If feed was the key, then the deer farms in Texas would be raising some humdinger big deer since they feed the hell out of them.

I put more stock in the idea that it is temperature related. You can see it in marine fish and mammals that are warm blooded. They are big.

Western moose are larger than eastern moose. I wonder how that pays into this? Is it colder in the western habitats than the eastern ones?

Maybe the key is mosquitos. I know those blood suckers work harder the farther north you go… Maybe those northern deer have to work double time to keep enough blood in ’em 😯 😀

[wildschwein]

#60925

Actually I never even thought about the Deer in Texas. I don’t know of any averages, but the ones I have seen on tv certainly didn’t seem as large as the Deer up here. Perhaps the feed they are given is driven more toward antler growth rather than body size?

On the other side of the coin, I can definately see how the browse this far north has its advantages. Even without the agriculture (which the Deer are definately taking advantage of), every spring brings forth a wide array various high nutritional value feeds. And in most areas the ungulate numbers are nowhere near high enough to consume it all, so the Deer don’t suffer from a lack.

Is this the same in Florida or Texas I wonder? Are the Deer populations so high in these states that the best browse might have already been over browsed or eliminated completely? And what is regrowth like in the spring?

But then you have the Moose situation. I don’t think the browse situation is so much different between the populations in Alberta and Alaska/Yukon. And the Moose in Alberta can and do take advantage of agriculture. Yet Alaska/Yukon Moose are by far the larger.

And don’t even get me started on the mosquitoes! Little buggers (ckickadee size) are just starting to come out around here. A man just don’t have enough .410 shells to deal with them :wink:.

[skifrk]

#61117

My experiences of living in NC and Virginia is that yes in the spring there is a lot of varied flowers and grass for nutrition, however the numbers of deer are dense so they eat it quickly. As far as the temperate being a factor, I can’t find it now but didn’t Texas import once a few deer from the north area like either Wisconsin or Alberta to try and give there deer big bodies but I never saw the research results so hard to say what happened. If you look at humans and who as a group populated an area and where, you will notice in say Greece or Italy where it is warmer that people have a finer bone structure i.e. thin bones to support less weight. However if you then look at say the Slavic’s or more northern people you will find them to have a heavier bone structure to support more weight to live off of.

[David Petersen]

#62498

Justin — I won’t enter the nutritional discussion, but will say that LeRue wrote some good and informed books but much of his info was second hand … from true researchers like Geist. In my books, and while I liked LeRue’s work, there is no comparison so far as knowledge between the two, with Val Geist way on top, in another whole class in fact. And too, another top-end bio friend of mine is fond of saying “Bergmann’s rule isn’t a very good rule.” Canids are a classic example of where it fails, with the farthest north species being the tiny Arctic fox. IMHO, it makes sense in lots of cases but leaves a lot of room to differ as well. About diet–which must include naturally occurring minerals in the soil and thus forage, when we’re talking about cervids–I can comment re N. American elk “subspecies” insofar as Geist and other respected elk experts feel certain that if you took a sample population of Yellowstone elk and plopped them down in central CA, and took another sample of Tule’s elk from CA and put them in CO, in a few generations the Tule would be big as Yellowstone and the Yellowstone dwarfed to Tule size. Which is to say that nutrition is a major player in size and can’t be ruled out. It’s all fun.

[wildschwein]

#62696

Thank you everybody for the replies and thoughts so far.

You are right Dave, it is all fun. And I can definately second your opinion on Dr. Geist’s work, then man had definately put his time in. I am currently reading his book Mule Deer Country, and already he has made several points that I hope to discuss on this forum.

My own opinion on Bergmann’s rule after much discussion and thought, is leaning towards the sceptical side. While it makes sense under certain circumstances, I do not think it is the tell all, end all rule that my high school science teacher would have me believe.

I can only hope more work will done on this subject in the future. It almost makes a fella want to back for more schoolin… Well almost :wink:.

Now if only someone would figure out why these damn skeeters are so big…

[Bruce Smithhammer]

#16737

Given all the glaring exceptions to Bergmann’s “rule,” I’d say there is probably a lesson in there somewhere about expecting nature to adhere to our rules. We sure put a lot of energy into trying to make it all neat and orderly, don’t we?

[Mark Turton]

#16777

And look what happens, about the time you’ve beat it into submission, its time to start all over again, perhaps we should learn to live with it ‘as nature intended’

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