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#505994 - 11/25/07 09:30 AM Harvest ratio and % benefit??
fishboy1
16 Point


Registered: 01/13/03
Posts: 10574
Loc: Warren Co

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Can a biologist who has actually studied this please answer?

Suppose A TN deer herd is at capacity and is NOT being managed for trophy antlers, just a healty herd. Herd is approx 2:1 does to bucks.
And harvest is 52% bucks and 48% does.

First, Is this an acceptably healthy herd?

2. What are the benchmarks where the herd is "healthy, acceptable, marginal, introuble?"

3. What benefits will the herd see if the harvest ratio is reversed? 52% does and 48% bucks?

4.Is there a way to quantify the benefits?

5.In a state like TN that does not experience any significant winter kill, are the benefits of such a switch going to make any difference to the actual herd health either long term or short term?
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#506280 - 11/25/07 12:59 PM Re: Harvest ratio and % benefit?? [Re: fishboy1]
Anonymous TnDeer Old Timer
Unregistered



uh, bro, no difference if you switch the percentages. insignificant. now if you switch the 2:1 ratio, bingo!
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#508170 - 11/26/07 04:10 PM Re: Harvest ratio and % benefit?? [Re: ]
AlanP
TWRA Biologist
8 Point


Registered: 10/02/02
Posts: 2486
Loc: Tennessee

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Fish,

I posted this in response to the same thread you started in the "Serious Deer Hunting" section:

I really don't have time to get into this, and I have a lot of other stuff that I should be doing instead, but...

I want to clear up some misconceptions, in my opinion, about the benfits of taking as many does as bucks everywhere, in all situations. But first, a little history.

Twenty or thirty years ago, I remember reading about statewide deer kills, in the United States, in Field and Stream, or Sports Afield, or some such, and I was amazed that Texas had a deer kill of 500,000, Mississippi killed 250,000, and Alabama killed 250,000. So, between just three states, they were killing one million deer annually. (At one time, the Llano basin in Texas had the highest deer densities on earth)I read this at a time where I had been hunting for several years without even seeing a deer in my state. Obviously, the deer herds in those states had already matured while other states were in the infancy of deer restoration.

Texas, Alabama, Mississippi, and probably Georgia, along with a few northern states, already had well established, mature deer herds, while the rest of us were still trying to restore them. There were many states with large sections sans any deer. During that restoration phase, does were sacred. Does were not to be shot, under any circumstances, so the population could grow. As deer populations began reaching a "cultural" carrying capacity (the point where a lot of people said, "OK, dammit, that's enough deer") the antlerless harvests started up. In Tennessee, the first real doe harvests started in the mid-1980s, while we were still stocking deer.

During those restocking years, any buck was a "good" buck. Close to 80% of the harvest were yearlings. Not many bucks reached the older age classes. But the hunters were able to take "a deer" once in a while.

Meanwhile, Texas, Georgia, and Mississippi, in particular, had reached a point where hunters had become dissatisfied with the little bucks, and the deer managers were becoming alarmed at the explosive growth of deer populations. Hunters wanted bigger bucks, managers wanted to halt population growth, and the best way to accomplish both goals was to cut back the number of little bucks killed and dramatically increase the doe harvests. One way to accomplish this task, and measure success, was to get harvests of does to equal harvests of bucks. In addition to limiting herd growth, more bucks would reach older age classes, and a lot of mature bucks in the population would affect herd dynamics and social interactions. There would be more competition during the rut for available females, creating stupid, unwary, big bucks running under tree stands.

From those states, the basics of Quality Deer Management took root. Pass young bucks, shoot lots of does, improve the habitat. That made sense, and still does make sense.

Remember, however, Tennessee was still stocking deer in 1985. There are some counties with deer herds well below their potential. Yet there are other Tennessee counties with deer densities which rival any in Texas, Mississippi, or Georgia.

Now, with that as background information, I would like to give my opinion regarding the "benefit" of a 1:1 sex ratio in Unit B counties. And I do so, even though I am not the most qualified, since I am on the other side of the state.

There are two ways to achieve an equal harvest of bucks and does, with the goal of equalizing the sex ratio of the population. You can shoot fewer bucks, or you can shoot more does. Here is a very simple example:

A population of 100 deer, with an annual harvest of 30 bucks and 10 does, changed to:

A population of 100 deer, with a harvest of 10 bucks and 10 does, OR

A population of 100 deer, with a harvest of 30 bucks and 30 does.

In the first instance, 1:1 is achieved by reducing buck harvests. In the second, by increasing doe harvests. (or there could be a middle ground if the harvest was altered to 20 bucks and 20 does)

The point is... There is a big difference in "effects produced" depending on which method is used to achieve a 50:50 buck:doe harvest. If you just cut back the number of young bucks, but not the number of does taken, the population can still grow at the previous rate, but more bucks will reach older age classes. If you just raise the number of does taken, but don't change the number of young bucks taken, you slow herd growth, and you do not produce more older age bucks (in fact, you may have fewer old bucks, because you might reduce fawn recruitment into the population). (I know, I know, BSK can jump on me for that simplification, because there is a compensatory increase in recruitment and survival if the population is reduced)

So, now we have hunters who would like to see the Unit B antlerless opportunities expanded. They want to shoot more does. One reason for this desire is to create a 1:1 sex ratio, along with the corresponding benefits. The problem is, in my opinion, the wrong way to do it is "just let them shoot more does" until they are shooting as many does as they are bucks. All that will do is reduce herd growth, without increasing older age bucks. There will be no "improved herd dynamics" because the older bucks will still be absent. In the words of on biologist, it would put Unit B back to 1985.

OK, so let's reduce the buck harvests in Unit B to a level equal to the doe harvests. OK, great. But, how? We dropped the limit from 3 down to 2 bucks, yet, that has had no apparent difference. The bucks harvests appear to have continued on the same course as they had been going, before the reduction. In other words, the reduction in the buck bag limit seems to have saved very few bucks in Unit B. Would reduction to 1 buck in Unit B produce the desired effect? It might, but there are very, very, few hunters who want to see a bag limit of 1 buck in East Tennessee.

I guess I am arguing for (or against) the simplification that a 1:1 sex ratio, achieved by a 50:50 buck:doe harvest, is not the same in all instances. Nor is it the right thing to do, in all instances. In a mature deer herd, if it is achieved by BOTH a reduction in buck harvests AND an increase in doe harvests, it could very well be the best management option. If it is a growing herd, and a 50:50 harvest is achieved solely by increasing doe harvests, WITHOUT a corresponding reduction in buck harvests, it may well be the worst.

One final thought... I had a biologist say to me, a few years back, "This 1:1 sex ratio stuff is like a chartreuse rubber worm."
When I asked him to explain he said, "You know how some big TV fisherman has a show and catches a great, big bass on a chartreuse rubber worm, and for the next couple weeks, all the fishermen want a chartreuse rubber worm because it's the only way to catch a big bass? That's what this 1:1 sex ratio has become. It is the chartreuse rubber worm of deer management."
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#508347 - 11/26/07 06:10 PM Re: Harvest ratio and % benefit?? [Re: AlanP]
Worm
18 Point


Registered: 09/06/00
Posts: 21700
Loc: Huntingdon, Tn

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 Originally Posted By: AlanP
I really don't have time to get into this,


My god I would not of had time to read it if you had more time. \:D
You must type 100 wpm.


Great explanation written to where even I could understand. \:D
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#508356 - 11/26/07 06:12 PM Re: Harvest ratio and % benefit?? [Re: AlanP]
fishboy1
16 Point


Registered: 01/13/03
Posts: 10574
Loc: Warren Co

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Alan,
The "Chartreuse rubber worm" comment is a classic!

It seems to me that the state is in Excellent shape overall.

That is not to say that some properties are in need of some adjustment. Just look at Montgomery Bell SP., browse lines 6' high and skinny deer chowing down on fescue. Couple miles up the road is a highly managed property with lots of food that is producing some decent bucks and fat does. But neither property is an indicator of what the "average" property is like.
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If you can't trust people with freedom, how can you trust them with power ?




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#508666 - 11/26/07 08:38 PM Re: Harvest ratio and % benefit?? [Re: Worm]
AlanP
TWRA Biologist
8 Point


Registered: 10/02/02
Posts: 2486
Loc: Tennessee

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 Originally Posted By: Worm

You must type 100 wpm.


Nah. 80. If they're little.
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If you don't look at the teeth, you're guessing at the age.

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#508941 - 11/27/07 05:11 AM Re: Harvest ratio and % benefit?? [Re: AlanP]
Worm
18 Point


Registered: 09/06/00
Posts: 21700
Loc: Huntingdon, Tn

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 Originally Posted By: AlanP
 Originally Posted By: Worm

You must type 100 wpm.


Nah. 80. If they're little.

Wow

When you get time I would like to read any info you can give on the restocking project of black panthers and what size we should pass up to help the quality black panter project.
Also when are you going to be back on the radio? I have a bunch more questions I need to call in? \:D

That was great.
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#510571 - 11/28/07 08:43 AM Re: Harvest ratio and % benefit?? [Re: Worm]
BSK
Jerkasourous of the non-typical kind
Non-Typical


Registered: 03/11/99
Posts: 65979
Loc: Nashville, TN

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Great stuff Alan.

And I agree about the 1:1 sex ratio thing in practical terms. Yes, near a 1:1 ratio is biologically best for the herd, but from a hunting standpoint, I don't recommend everybody try and go there. I've worked with herd managed to 1:1 and even as far as 2 bucks per doe, and most hunters wouldn't like the results. Yes, bucks are MUCH more active during daylight, but the amount of doe harvest necessary to produce such a ratio will drive all does nocturnal. You will virtually never see a doe during daylight, and that level of harvest pressure can reduce ALL daylight deer activity.

I recommend anywhere from from 1.5 does per buck to 2 does per buck as the best balance between herd health and hunter satisfaction. If hunters/amangers are willing to put up with less total deer sightings and far fewer doe sightings, to acheive more buck activity during daylight, then push for 1.5 does per buck. If not, 2:1 is still OK.
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#510576 - 11/28/07 08:49 AM Re: Harvest ratio and % benefit?? [Re: BSK]
BSK
Jerkasourous of the non-typical kind
Non-Typical


Registered: 03/11/99
Posts: 65979
Loc: Nashville, TN

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fishboy1,

To answer your question, those harvest percentages are too close to make any difference if swapped.

For large areas (county-sized), a nearly balanced harvest percentage between male and female eventually leads to a fairly balanced adult sex ratio within a couple of years. However, on small properties, a balanced harvest ratio may not lead to a balanced sex ratio, as deer move around quite a bit, considering yearling buck dispersal, shifts of doe groups to better resources, and seasonal older buck shifting.

For small-land management the most powerful players in herd perfomrance revolve around herd density in comparison to food availability and food quality. Keeping the herd well below the biological carrying capacity will produce significant dividends. However, the most powerful management tool available to the small-land manager is habitat management. Managers will see the greatest benefit from improvements in habitat quality.
_________________________
"Know where you stand, and stand there" --Jesuit Father Daniel Berrigan

"There is no reasoning someone out of a position he has not reasoned himself into." --Clive James

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#520445 - 12/07/07 03:36 PM Re: Harvest ratio and % benefit?? [Re: Worm]
Macdaddy3231
Button


Registered: 10/24/07
Posts: 4
Loc: Middle Tennessee

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Do you mean the mountain lion restocking roject? Black panthers don't exist in N. America.
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