Help with Buck:Doe ratio

[lacrow]

Am i correct in saying that if you started with 3 does and 1 buck and 1/3 of the does harvested each year the bucks would out number the does pretty quick?

bucks does fawns
1 3 6
4 4 8
8 6 12
14 8 16

I no there are alot of variables that would play into this but is it possible by protecting bucks and targeting does to acheive more bucks than does? I have got to be missing something here.

[BSK_]

Originally Posted by lacrow

Am i correct in saying that if you started with 3 does and 1 buck and 1/3 of the does harvested each year the bucks would out number the does pretty quick?

bucks does fawns
1 3 6
4 4 8
8 6 12
14 8 16

I no there are alot of variables that would play into this but is it possible by protecting bucks and targeting does to acheive more bucks than does? I have got to be missing something here.

Somehow you're not adding the fawns correctly. You added three males to the second year's totals, but only 1 female. In addition, I would use a more realistic fawn recruitment rate of 100% instead of 200%.

I'll start with a larger number so that decimals are easier to round. I'll also round up on fawns so there is always an equal number to split male and female.

If 1/3 of the females are harvested, no bucks or fawns harvested, fawn recruitment is 100%, fawns are split 50/50 male/female, and the starting sex ratio is 3 does per buck:


bucks--does--fawns

Year 1
pre-hunt: 33--100--100
post-hunt: 33--67--100

Year 2
pre-hunt: 83--117--118
post-hunt: 83--78--118

Year 3
pre-hunt: 142--137--138
post-hunt: 142--91--138

Year 4
pre-hunt: 211--160--160
post-hunt: 211--107--160

Year 5
pre-hunt: 291--187--188
etc.


So in this example, if no bucks are killed, the skewed 3:1 sex ratio evaporates and sex ratios are basically balanced by Year 3. In following years, there are more bucks than does, and the sex ratio becomes even more dominated by bucks as time goes on.

The interesting thing is, even when 1/3 of all does are removed each year, the adult femal population keeps growing. That's really something to think about. Removing 1/3 of all does didn't control herd growth.

Playing with these simplistic population models can be eye-opening. Even if you start with an unrealistic sex ratio of 4 does per buck, if you harvest an equal number of bucks and does each year, the sex ratio will still eventually balance out due to the recruitment of so many sexually-balanced fawns into the adult population.

[banc123]

Math only works in a pen, doesn't work free ranging situations, especially under a few 1,000 acres as new does and bucks will come in and fawn bucks will leave.

If for every doe shot a new one moves in and the fawn bucks leave, your in trouble quick if new bucks don't move in.

[BSK_]

Originally Posted by banc123

Math only works in a pen, doesn't work free ranging situations, especially under a few 1,000 acres as new does and bucks will come in and fawn bucks will leave.

If for every doe shot a new one moves in and the fawn bucks leave, your in trouble quick if new bucks don't move in.

There are many, many problems with simplistic numerical models, and they really only work over very large areas (so that dispersal is not an issue), but again, they do show how population growth works, and how highly skewed pre-hunt sex ratios are impossible in most real-world situations.

[lacrow]

Okay , what in the real world would you expect to see if only does where harvested for say 3 years on a thousand acres starting the first year with herd well below carrying capacity? Can in the real world the btd ratio be balanced are slighty more bucks than does?