While I never think I'm smart enough to recreate the wheel, something has been bugging me and I haven't seen it addressed by others so here goes.
Basically, the "easy math" used to estimate next year's wild horse and burro numbers is as follows: Take this year's number, subtract the number removed and add back in the number of births. Say, there are 33,000 wild horses left on the range and the BLM removes 10,000 of them. That would leave 23,000 horses. Then you add back in 6600 horses (20% increase in population) and the number you get would be 29,600 left on the range. Of course, even that lazy math doesn't jive with the BLM's reported numbers year over year but that would be a simple way to calculate the number remaining. However, it could be wrong and of the course of several years, it could add up to a significant number. Here's why I have bothered to write this today:
If the wild horse population increases by 20% every year (per the BLM) then you have to say the actual birth rate is a little higher to account for deaths. So, let's say 30% pregnancy rate. Who knows? I hate to start out the hypothesis with shaky math, but since we are depending on the BLM for our head count, well, we're already screwed.
So, 33,000 wild horses at the beginning of February of this year. Accepted on faith since there is no proof and the BLM isn't going to provide the data that they supposedly collect on a yearly basis to make their population count. And we also accept the BLM's word that the population increases by 20% every year.
Generally, sixty percent of wild horse populations are mares so that means 19,800 mares in a population of 33,000 wild horses. To get a population increase of 6,600, then 33% of those mares have to have live foals. Actually, the percentage of mares to foals gathered seems to be a little less from what I've seen, but since some at the BLM don't think that data is for public consumption, then who knows for sure?
So, if the BLM rounds up 11,000 horses during the year, you could assume that 6600 of those rounded up (60%) would be mares. Since the BLM gathers at different times of the year, it's also possible to assume that 33% of the gathered mares are pregnant, 33% have foals and 34% have no foals at the time of the gathers.
The ones that are pregnant is where my hypothesis gets tricky. I might wake up in the middle of the night and decide that I'm off base, but here goes.
If these mares are pregnant when rounded up, then that means the BLM could be removing up to 1,980 horses more than the official number (assuming these mares would have had foals if left in the wild and then go on to have their foals in captivity). The fact that the BLM can say with a straight face that there was no change in the wild horse population from FY 2010 to FY 2011 with no justification is even more astounding because of the above hypothesis.
LIke I said, I might erase this in the middle of the night if I think of something else that would impact the numbers. The gather and removals are clearly not a simple numbers game. If my thoughts here are correct, then surely someone at the BLM has already thought this out and understands how misleading the roundup numbers really are. And how about those yet-to-be-born foals are accounted for in LTH,? Well I know there are people thinking about that.