Herd Stabilization and Population Estimates 
deerfly 
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RE: Herd Stabilization and Population Estimates
2011/02/15 19:12:12
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One thing that we shouldn't overlook is that the PGC is claiming the population trends are stable, rather than claiming the OWDD or PS density remained stable. So if the population trend was decreasing in 2005 and the population continued to decrease from 2006 to 2009, did the population trend remain stable?
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RSB
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RE: Herd Stabilization and Population Estimates
2011/02/15 21:56:33
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ORIGINAL: deerfly
One thing that we shouldn't overlook is that the PGC is claiming the population trends are stable, rather than claiming the OWDD or PS density remained stable. So if the population trend was decreasing in 2005 and the population continued to decrease from 2006 to 2009, did the population trend remain stable?
The entire problem with your line of thinking is that you didn’t understand the estimated data released about the populations, expressed in any manner, before 2005, in 2005 or in any of the years since. You have simply taken that middle number, which is the only number they used to release, and used it as the number of deer that exist in each of the yearly preseason population estimates. That is not the correct way to use the data. The correct way is as follows and put into as simple explanation as I can provide. That middle number is simply what they believe is most likely the correct preseason estimate based on the next fall deer harvest results using the sex, age and kill data. But, the correct number might really have been as low as the lower of the three numbers or it might have been as high as the highest of the three numbers. Then since there is a 90% confidence interval there is also a 10% change something totally abnormal occurred in that year’s harvest results and the real population number was somewhere lower than the lowest number or higher than the highest number. Therefore, since any one of those three population estimate numbers is within the range of the three previous year’s estimated numbers it is believed the actual preseason population is somewhere within the same range as the previous year’s estimate and thus the deer population is stable, based on the range of estimate. When you understand the data and use it correctly the estimated preseason population in unit 2F doe show it as being stable from 2004 through 2009 though it indicates a slight decline from the 2003 preseason population estimate. But, you really are demonstrating the exact reason they stopped releasing the estimated data before. I fully agree with it being released though because in my opinion not releasing the data does create a perception of trying to hide the truth. That perception really is false, but we need to both release it then try to do a better job of explaining what it REALLY means instead of just allowing some people to misuse it into ways it shouldn’t be used or can’t be correctly applied. R.S. Bodenhorn
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S-10
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RE: Herd Stabilization and Population Estimates
2011/02/16 09:33:32
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The problem with the POPULATION TREND data is that it takes six years after the fact to really know what you have and the varience is so great between the high and low boundries that you could be in a fairy steep decline and not have it show until it"s reached a critical level.
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deerfly
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RE: Herd Stabilization and Population Estimates
2011/02/16 18:18:12
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Here is the formula the PGC uses to estimate the yearly change in DD in each WMU. Notice that they don't use 3 or 6 year averages. They use the estimated populations in the prior year compared to the estimated populations in the following year just like I did. Population trends are reported as changes from year to year (λ) and are calculated as
t
t
N
N
λ
ˆˆ
1+
= where
1+tNˆ is the deer population in year t+1 and tNˆis the deer population in year t
(Skalski et al. 2005). A value of λ = 1.00 would indicate no change in deer population. Values
greater than 1.00 indicate increases and values less than 1.00 indicate decreases. Deer
management objectives and recommendations are based on population trends. As a result, we do
not make management recommendations in response to individual λs, but rather we based
management recommendations on multi-year trends.
As usual it didn't copy and paste the way it was presented in the AWR, but if you aren't familiar with the formula, you can find it in the 2009 AWR. But, you really are demonstrating the exact reason they stopped releasing the estimated data before. I fully agree with it being released though because in my opinion not releasing the data does create a perception of trying to hide the truth. That perception really is false, but we need to both release it then try to do a better job of explaining what it REALLY means instead of just allowing some people to misuse it into ways it shouldn’t be used or can’t be correctly applied. For 25 years the PGC has been telling hunters that they knew how many deer were harvested , how many PS deer we had and how many OWD we had each year. But in 2006 that all suddenly changed and the PGC claimed they didn't know how many deer we had and it didn't matter since the deer were being managed based on deer population trends and their effects on forest regeneration. However, at the same time the PGC claimed that antlerless allocations and season length was based on 3 or 6 yr. population trends. So, if you want to impress the members of this MB and assure us the PGC really does know what they are doing, please explain the decrease in antlerless allocations and decrease in season length in 2G, even though forest regeneration is still rated as poor and the herd is rated as stable?
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RSB
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RE: Herd Stabilization and Population Estimates
2011/02/16 19:39:06
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ORIGINAL: deerfly
Here is the formula the PGC uses to estimate the yearly change in DD in each WMU. Notice that they don't use 3 or 6 year averages. They use the estimated populations in the prior year compared to the estimated populations in the following year just like I did.
Population trends are reported as changes from year to year (λ) and are calculated as
t
t
N
N
λ
ˆˆ
1+
= where
1+tNˆ is the deer population in year t+1 and tNˆis the deer population in year t
(Skalski et al. 2005). A value of λ = 1.00 would indicate no change in deer population. Values
greater than 1.00 indicate increases and values less than 1.00 indicate decreases. Deer
management objectives and recommendations are based on population trends. As a result, we do
not make management recommendations in response to individual λs, but rather we based
management recommendations on multi-year trends.
As usual it didn't copy and paste the way it was presented in the AWR, but if you aren't familiar with the formula, you can find it in the 2009 AWR.
But, you really are demonstrating the exact reason they stopped releasing the estimated data before. I fully agree with it being released though because in my opinion not releasing the data does create a perception of trying to hide the truth. That perception really is false, but we need to both release it then try to do a better job of explaining what it REALLY means instead of just allowing some people to misuse it into ways it shouldn’t be used or can’t be correctly applied.
For 25 years the PGC has been telling hunters that they knew how many deer were harvested , how many PS deer we had and how many OWD we had each year. But in 2006 that all suddenly changed and the PGC claimed they didn't know how many deer we had and it didn't matter since the deer were being managed based on deer population trends and their effects on forest regeneration.
However, at the same time the PGC claimed that antlerless allocations and season length was based on 3 or 6 yr. population trends.
So, if you want to impress the members of this MB and assure us the PGC really does know what they are doing, please explain the decrease in antlerless allocations and decrease in season length in 2G, even though forest regeneration is still rated as poor and the herd is rated as stable?
Thanks but I don’t need the formula, I have had for a long, long time and even had to pass tests based on it in the past. That is why I have always pointed out, and tried to make you understand, how wrong you were in so many of your posts concerning your use of the OWDD and other population estimates. As for the decreases in the 2G antlerless allocations and season lengths a lot of that falls right back to the same old public and political pressure tactics of the past and the lack of ability some have in learning from past history and/or mistakes. We are seeing those same mistakes being expanding over larger areas of the state and most likely we will both live long enough to see even more deer habitat damaged to the point it will not support very many deer as the reward. R.S. Bodenhorn
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deerfly
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RE: Herd Stabilization and Population Estimates
2011/02/16 20:00:46
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Thanks but I don’t need the formula, I have had for a long, long time and even had to pass tests based on it in the past. That is why I have always pointed out, and tried to make you understand, how wrong you were in so many of your posts concerning your use of the OWDD and other population estimate If I am so wrong then why isn't the PGC just as wrong for using the same data I am using to prove over and over againyou have no idea what you are talking about. As for the decreases in the 2G antlerless allocations and season lengths a lot of that falls right back to the same old public and political pressure tactics of the past and the lack of ability some have in learning from past history and/or mistakes So are you saying the PGC is lying when they claim the antlerless allocations are based on forest health and deer population trends.? Is that why the PGC reduced the allocations in most WMU's in 2010? Are you saying the USP is winning even though they had their case dismissed? We are seeing those same mistakes being expanding over larger areas of the state and most likely we will both live long enough to see even more deer habitat damaged to the point it will not support very many deer as the reward.
The PGC is managing the statewide herd at less than 12 DPSM,while Valley Forge and Gettysburg supported 200 DPSM and the herd was still below the max. CC of the habitat. Therefore The MSY CC of WMUs like 5B and 5A and 2C has to be over 50 DPSM, and will remain at or above that level for the foreseeable future no matter how over browsed the habitat the forest habitat might be.
post edited by deerfly - 2011/02/17 08:08:20
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DarDys
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RE: Herd Stabilization and Population Estimates
2011/02/17 08:00:01
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ORIGINAL: deerfly
One thing that we shouldn't overlook is that the PGC is claiming the population trends are stable, rather than claiming the OWDD or PS density remained stable. So if the population trend was decreasing in 2005 and the population continued to decrease from 2006 to 2009, did the population trend remain stable?
It doesn't matter if its deer or widgets, if there is a consistent trend around the trend line on a graph, the slop of the trend line is in a constant direction and doesn't look like a hockey stick at any point, then the "trend" itself is stable. So, yes.
The poster formally known as Duncsdad Everything I say can be fully substantiated by my own opinion.
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deerfly
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RE: Herd Stabilization and Population Estimates
2011/02/18 19:30:41
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While the PGC has a complex computer model for determining the OWDD I stumbled on a simpler, down and dirty method for determining the OWDD in any given WMU. if you multiply the buck harvest by 5 you get the approx. OWDD. For example ,in 2000 when the PGC said we had 1M PS deer we harvested 203 K buck. Therefore the harvest ratio was 1 buck for every 5 OWD.
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