Recently I've gotten into a discussion with a animal-rights activist regarding hunting in general and compensatory rebound effect.

I'd heard this brought up before by ARA-folk before; so it's not new to me, but....

I've hunted deer(Off and on) for decades:and I've never heard it discussed much by hunters. My father(a very avid deer-hunter for more then 40 years)I'm sure, never even heard of it!

I did a bit of poking about on the internet regarding CRE and frankly; pretty much the only people who discuss it are animal-rights folk. This makes me wonder how much of CRE is real and how much to propaganda.

So: What's up with CRE? Real or BS? And what does it mean to hunting?

Much of it depends on herd size and the condition of the habitat. It boils down to nutrition rather than any other factor.

Habitats with too many deer usually have limited forage, thus less nutrition. So does might be undernourished and thus either not fawn at all, miscarry or drop only a single one. And then those fawns might not survive their first winter.

In the best of times, the same does will have twins or even triplets. Also, many does will fawn in their first year. BUT..without any limiting factor such as hunting, the effect will eventually lead to overpopulation and a crash in herd size as the habitat suffers. This is why the RIGHT management is necessary to keep the numbers within the ability of the habitat to support it, and to not kill more than can be replaced.

Right now in much of the West, it isn't the deer numbers leading to poor reproduction among mule deer; it's the lack of moisture at the RIGHT times of the year -- winter and late summer.

Even with forage available, it needs rain to produce nutrition. So the fawn production/recruitment is way down. And it takes more than one year of good moisture for a deer population to recover. But going out and killing a bunch of deer isn't going to help much if the remaining deer still have a poor food supply.

Here's a snippet from an article I did 10 years ago. The quotes are from Ray Lee, who was then the Big Game supervisor for the AZ G&FD:

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Lee points to the 1998 deer population jump as a perfect example of what can happen.

"We had normal winter rains, good spring rains and adequate summer rains. Statewide, fawn recruitment went to nearly 40 fawns per 100 does in areas of the state where it had dropped to as low of 20 fawns per 100 does. On the Kaibab Plateau, somewhat different climatic conditions caused the corresponding recruitment to rise to nearly 90 fawns per 100 does. It was an exceptional year. Unfortunately, it was only one, and that won’t do it.”

According to Lee, the lack of moisture to sustain ideal deer populations started in 1988 and pretty much reflects the trend that occurred about 40 years ago.

“Our deer numbers reached the highest ever in the 1960s, but the population dropped very rapidly from those numbers to all-time lows by the late 1970s. That’s why we put deer on the permit system in 1972. And if we look back at the weather conditions from the late 1960s and early 1970s. we would quickly see they mirror the same patterns that are occurring right now. The deer population is also following the pattern.”

“Then the deer numbers shot up again in the early and mid-1980s because we had an anomaly of sorts with rains that produced three 100-year floods over a five-year period. Even the normally dry Salt River was running at 200,000 feet per second and washing out bridges in downtown Phoenix.

“The result on our deer herds was quite predictable. For a few years running, all of the does had twins, their twins had twins, and those twins…and so on. So we wound up with more deer than we knew what to do with. Over the next several hunting seasons, we had more permits available than we had hunters to apply for them. In 1986, we set the all-time record with 95,821 permits. That is more than double the permit allocation for 2000.

“The one thing hunters shouldn’t do, however, is think we’ll ever get to that point again. The floods were very uncommon occurrences that created the best deer habitat we’ve ever had. So unless those conditions repeat themselves, which isn’t too likely, our traditional optimum deer numbers will be considerably less than what we had in 1986.”

Fortunately, even though the permit numbers are at an all-time low right now, there are still more deer today in Arizona than there were in the 1970s when the population hit bottom. The reason is a different management concept put into place by the AGFD.

When the herds plummeted in the 70s, the hunter success did likewise, averaging 16 to 18 percent statewide -- a result of supply and demand with only so many deer to go around. This prompted many complaints from hunters. Rather than allow that trend to continue, the game department began adjusting the permit allocation whereby the hunter success remained fairly consistent at 21 to 24 percent in most units. So while fewer hunters go afield now, more of those that do get to a tag a buck.

The relationships between moisture and deer populations can be somewhat difficult to understand, but what it mostly comes down to is habitat.

The simple explanation: when plants gets rained on they grow and provide moisture, nutrition and cover for deer. And obviously, lots of rain also provides more standing water. The more complicated explanation involves all the interrelationships within the simple one, including what appears to be increased predation.

Too heavy, Tony. It's easier to blame wolves, coyotes, and politicians.

As often, great stuff Tony, thanks.

I was pretty conscious of those rainy period in Arizona, even though I live in Georgia, my uncle is a bridge designer in Tucson, and damn was he busy doing 're-designs' at that time!

When are you going to do a Muley or Whitetail book Tony?

quote:

Originally posted by wasbeeman:
Too heavy, Tony. It's easier to blame wolves, coyotes, and politicians.

Actually, predators can have an adverse effect that biologists refer to as additive mortality. Again, it just depends on the factors involved.

For example, if a wolf kills a starving deer, it is considered a compensatory mortality because the deer would have likely died a natural death anyway to be replaced in the normal reproduction cycle. In contrast, the death of a healthy deer is considered to be additive rather than compensatory.

Then again, if the biologists estimate the annual predator kill and add it to the hunting havest and natural mortality figures when setting harvest limits, the wolf kill could be considered compensatory just as the death of a heathy deer by a hunter's bullet or arrow would be. In other words, one mortality type was simply compensated for by another one.

Normally, hunting comes under the compensatory type. Game departments estimate herd numbers and what the natural mortality might be. They then set harvest limits if necessary so the total kill plus the natural mortality isn't greater than the herds can replace -- compensate for -- the following year. Thus this is why the AR folks use it to make their point. But again, there are too many factors that can change the outcome.

All this compensatory and additive theory came about sometime in the early to mid-1900s and is the basis for much of today's management concepts. Yet even though the basic theory is sound, it's far from an exact science. Reason: It's very difficult to determine whether each death of an animal is compensatory or additive. Plus, there's always something that can come into play to affect the next year's result.

The floods mentioned in my other message are such factors that led to an OVERabundance. On the other end, a severe winter after the hunting season could result in an unplanned, depressed population that might not recover for a couple years.

All of this doesn't apply to just deer. Even predator numbers depend on habitat conditions because that's what keeps their prey numbers up. As soon as the prey numbers drop way down, the predator population in the same habitat area usually follows. They can't exist where there's nothing to eat. Unfortunately, this doesn't happen until the prey have been pretty much decimated. It amounts to chaotic "management" -- sharp rises and falls of a population.

Birds, such as quail, and small game also go through the cycles. The more rain over the winter and early spring, the better the habitat. Thus bird numbers or rabbit populations, etc. also increase and so do the predators that eat them.

Politicians are a different problem altogether.

Another snippet from one of my old articles on quail:

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A few decades ago, long-retired AGFD biologist Steve Gallizioli conducted an extensive study on quail. The program lasted many years and consumed hundreds of man-hours. When it finally ended Gallizioli came up with two interesting results. His research showed hunting has little or no effect on quail numbers, and the quail population is related more to the success of the hatch than to carry-over from the previous year. The biggest factor was rain. While Mearns’ quail depend more on summer rains, the mid-winter rains from late November and into March influence the Gambel’s hatch the greatest.

Gallizioli discovered good plant growth in late spring and early summer due to the winter rains was a key factor. He also found if the moisture was dispersed over a longer time to saturate the soil, more quail resulted.

So biologists knew green vegetation was necessary in the Gambel’s reproductive scheme, but they weren't quite sure why until research by the University of Arizona unraveled that part of the mystery.

The research showed higher concentrations of Vitamin A in the bird's livers when they were mating and determined it was a key to the quail's sexual development for mating. Plants such as Vitamin A-rich alfilaria and storksbill raise the hens' hormone level, providing the ingredients for large broods.

Once the eggs hatch, the quail chicks also derive benefits from increased vegetation. The young birds need a large amount of protein to survive, and the copious vegetation provides that protein in the form of increased insect populations. When the plants eventually go to seed, both the juvenile and adult birds have a generous and nutritional food supply.

Gallizioli said the best indicator of how good the fall season will be is the preponderance of spring flowers.

quote:

Originally posted by Fish30114:
When are you going to do a Muley or Whitetail book Tony?

I've been working on another book in my spare time, which never seems to materialize.

But it's not single species oriented. It will cover hunting for all of Arizona's critters -- big game, upland, waterfowl, etc. I hope to get it done before I die.

These are a couple covers I've toyed with. All the pix are mine, of course.

Thanks for posting the articles,interesting stuff.

I will admit I had to google "compensatory rebound effect" to figure out what this thread was about at first....

The arabesque symbiotics of it all is not easily understood even by the people that make a profession of it. Whatever that means.

Tony,

The covers aren't bad, but you might consider one that actually shows human hunters...say an older mentor with a younger person watching game in the distance.

Iowanic, sorry for the mini-thread hihgjack--but


Tony, cool enough--I hope you finish it a lot sooner

I like both cover, probably cause I love big bull elk pics, but the one with the multiple species is really cool too.

Good luck on it!