Biology Notes 09/18/12

1. ∆N = Change in Population Size ∆N = (Births + Immigration) – (Deaths + emigration)

2. Dp = Population Density

Dp = N S

N= Population Size S = Space

Ex. Deer population goals may be expressed in terms of abundance or density. Density goals are shown as the average number of deer per square mile of "deer range" in the post-hunt population.

Deer range in Wisconsin is defined as all permanent cover-- forest, woodlot, brush-covered land or marsh-- at least ten acres or more in size. Agriculture and grass fields within 5 chains (100 m) of permanent cover are also included as deer range. Areas of permanent cover smaller than 10 acres can be included as deer range if they are known to be commonly occupied by deer.

Deer units close to Amery: 15, 16, 21, and 22 http://dnr.wi.gov/files/PDF/pubs/wm/WM0431.pdf http://dnr.wi.gov/topic/hunt/documents/fallabund.pdf http://dnr.wi.gov/topic/hunt/documents/falldeerperdr.pdf 3. PG% = Population Growth Rate

PG% = ∆N x 100% N

Ex. PG%= Day 1 – Day 0 x 100% Day 0

PG%/Day = PG% over the whole population study divided by # of days.

4. Estimating population increase:

I = R x N

I = population increase, R = population growth rate, N = current population size

I = PG% x N

Biological carrying capacity (K) is the maximum number of deer the landscape can support over a prolonged period of time. A deer herd managed at "K" will result in heavy competition between deer, over browsing, and a high percentage of winter mortality. Generally, population goals in forested units are set about 60-65% of K. A deer population managed at these levels has shown to result in a long-term sustainable harvest and a healthy deer herd.

The social carrying capacity is the number of deer that is less likely to cause excessive property damage, while still providing good recreational opportunities for hunting and viewing deer. 5. Estimating Deer Population Size:

WI DNR uses SAK method

SAK = Sex Age Kill

SAK Video

Ex. Buck Estimation: Bucks harvested out of 50 tags issued. Harvest rate = 20% 10/.2 = 50 Bucks

Doe to Buck Ratio = Population of yearling does harvested to yearling bucks harvested. The data shows that does live longer than bucks.

Doe Estimation: Doe to Buck Ratio x Bucks Harvested 2.3 x 50 = 115 Does

Fawn Estimation: Deer observations are made from July to September and a Fawn to Doe ratio is determined. Fawn to Doe Ratio x Doe Population 1.2 x 115 = 138 Fawns

Total Herd Estimate: 50 Bucks + 115 Does + 138 Fawns = 303