A unit of Lasting Forests Sustained forests; sustained profits evolving since March 30, 1999

Situation A

How many acres to you have? . . . 2000

The usual density is 1/30 acres. Thus, you know there are about 67 deer on the place.

How many deer did your group take? . . . 12

The reproductive rate in an unbalanced herd (excessive females) is probably close to 1.5 per female. Where 2/3 of the herd is female, then 67 x 0.67 = 45 females. These produce 67 fawns (45 x 1.5 = 67). The herd will increase; "habitat" will be damaged. An annual harvest of about one-half of the population - about 33 deer - is needed. About 20 of these should be does.

nbsp;	Females	Males	Total
Before	45	22	67
Harvested	20	13	33
After	25	9	34

Production: 25 x 1.5 = 37

Total: 34 + 37 = 71

We're still increasing; production will increase due to new food density per remaining animal. All numbers are estimates based on expected values. Variation in seasons and observers is expected.

Situation B

Acres 7000

Deer Density 1/30 Acres

Population 7000/30 = 233 total deer

Sex Ratio 25:100 80% female

Remove 25% (a managerial first estimate)

Crippling loss is about 20% of reported harvest (x)

233 x 0.25 = x + x (0.2)

58 = 1.2 x

x = 48 (the desired harvest from hunting legally and reporting harvest)

Past years (2-3) harvest has been 60% male.

48 x 0.6 = 29 bucks removed (reported)

48 x 0.4 = 19 does removed (reported)

48 total

Actually 35 male, 23 female removed (or 58 total)

Food available: 7000 units/233 = 30 units of food/deer

After hunt: 7000/(233-58) = 40 units of food/deer Extra food results in increased natality and longer reproductive life.

186 females producing 0.8 young = 149 young [+ females + males = total population of 382]

186 - 23 * 0.91 (having increased) = 149 young

149/233 = 0.64 increase

149/175 = 0.85 increase

For population stability, if 149 are produced, then legal hunting, crippling, poaching and natural mortality must equal 149.

This Web site is maintained by R. H. Giles, Jr.
Last revision January 17, 2000.