Stag1933 makes a good point,
"It`s not hard to count Deer accurately, it is imposssible."
First of all, no insult intended to anyone on this site, OK, but statistics and estimations are a big part of my job, so I had to chip in. I don't count deer unfortunately, but the principles are the same.
One thing that gets my back up is government departments or agencies producing meaningless or misleading figures, I would get sacked for doing it, why don't they?
Anybody, claiming to be a scientist, who states a single figure for any wild animal population is practising incorrect science or doesn't understand statistics or at worst is deliberately trying to mislead.
Strictly speaking they should quote a range consisting of low-mid-high cases with a "most likely" estimate given too for completeness.
However, what they typically do is count animals in a measured area, square miles, square kilometres or suchlike. And they use students/volunteers who don't always correctly identify species, or who even sit and make up the figures in the pub cos it was raining or too cold outside (I've caught researchers doing exactly that when I hired some), results from such work are obviously bullsh*t.
Even at best they extrapolate from a sample cos they can't (afford to) count everywhere, so they start small. Say they use 100 square miles and they estimate (first inaccuracy introduced) that there are 10 000 square miles of available habitat, the simple method is to multiply the number they recorded in 100 square miles by 100 and quote that as the total population.
Simple and almost certainly wrong as it assumes that they counted all the population in their 100 square miles (they almost certainly didn't = more inaccuracy) and, perhaps worse, it also assumes an even distribution or population density throughout the range for that species (more inaccuracy).
I've seen places where the munties were thick on the ground, 10 in a 10acre wood, other places only 2 or 3 on a 600 acre farm.
Which one is typical? Would the average be? Did I see all the animals in either place? Unlikely. And it's the same for all researchers, hence the need to quote ranges.
It's fun to count lots of munties/Sika or any deer, but as they move, hide, die and breed it's difficult to come up with a definitive population figure. Even trying to work out how fast the population grows/doubles is an estimate or more likely a guestimate.
Whatever, certainly in the case of munties they appear to thrive and I've seen them in places that were almost certainly free of them only 3 years ago, and I've even seen a few in northwest London within a couple of miles of Wembley. It looks like they are here to stay and that's great in one way at least, they taste good!
ATB
Geoshot