Estimating Big Game Weights
A Crash Course for the Curious
by Bill Jensen
Originally published in:North Dakota Outdoors
(September-October, 2000)
Official Publication of the
State Game and Fish Department
100 North Bismarck Expressway
Bismarck, North Dakota 58501-5095
This resource is based on the following source:
Jensen, Bill. 2000. Estimating big game weights a crash course for the curious. North Dakota Outdoors 63(3):26-27.
This resource should be cited as:
Jensen, Bill. 2000. Estimating big game weights a crash course for the curious. North Dakota Outdoors 63(3):26-27. Jamestown, ND: Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/mammals/bgame/index.htm (Version 11APR2001).
By nature, hunters are inquisitive. They ask a variety of questions about the game they seek. What do they eat? When are they most active? How large is the home range?
After an animal is down, hunters frequently wonder how much it weighed when it was alive. However, scales are seldom available in areas where hunters usually tag and field dress big game animals.
While it is seldom practical to get a total body or live weight of a freshly killed animal, it is possible make an accurate estimate of live weight after measuring a dressed animal on a scale.
Table 1. Equations for estimating live-weight from dressed weights of six North Dakota big game species (all weights are in pounds). | |
Species | Equation |
Bighorn Sheep | |
Ram | (dressed weight x 1.13) + 31.9 |
Elk | |
Cow | (dressed weight x 1.07) + 110.4 |
Bull | (dressed weight x 1.30) + 24.4 |
Moose | |
Cow | (dressed weight x 1.33) + 61.0 |
Bull | (dressed weight x 1.27) + 78.2 |
Mule Deer | |
Doe | (dressed weight x 1.28) + 3.6 |
Buck | (dressed weight x 1.20) + 9.9 |
White-tailed Deer | |
Doe | (dressed weight x 1.30) + 1.60 |
Buck | (dressed weight x 1.15) + 11.7 |
Pronghorn | |
Doe | (dressed weight x 0.95) + 38.7 |
Buck | (dressed weight x 1.17) + 16.7 |
(Pronghorn data from G.J. Mitchell. 1971. Journal of Wildlife Management. 35(1): 76-86) |
HOW IT WORKS
After determining the dressed weight of an animal, say a white-tailed buck,
use the appropriate equation listed in Table 1. If the buck weighed 150 pounds
dressed, multiply that times 1.15, and then add 11.7. The 184-pound-total
is close to the true live weight. The average and ranges of weights for each
North Dakota big game species is highlighted in Table 2.
Table 2. Average and range of fall live-weights in pounds for North Dakota big game species (all weights are in pounds). | ||
Species | Average Weight | Range of Weights |
Bighorn Sheep | ||
Yearling and adult males | 196 | 123-250 |
Elk | ||
Young-of-the-year | 298 | |
Yearling and adult females | 495 | 438-556 |
Yearling and adult males | 698 | 469-950 |
Moose | ||
Young-of-the-year | 432 | 310-500 |
Yearling and adult females | 879 | 600-1,160 |
Yearling and adult males | 891 | 550-1,300 |
Mule Deer | ||
Young-of-the-year | 79 | 65-90 |
Yearling and adult females | 138 | 110-170 |
Yearling and adult males | 163 | 125-255 |
White-tailed Deer | ||
Young-of-the-year | 80 | 55-105 |
Yearling and adult females | 131 | 90-208 |
Yearling and adult males | 168 | 100-242 |
Pronghorn | ||
Young-of-the-year | 77 | 70-82 |
Yearling and adult females | 108 | 91-124 |
Yearling and adult males | 117 | 100-134 |
(Pronghorn data from G.J. Mitchell. 1971. Journal of Wildlife Management. 35(1): 76-86) |
THE BIOLOGY BEHIND THE NUMBERS
To biologists, these equations are not just a string of numbers. They provide
insight about the animal and how well it was doing. For example, a heavier-than-average
fawn suggests the animal has had an excellent diet and could have reached
puberty and become pregnant at six months of age. A heavier than average doe,
on the other hand, may suggest she lost her fawn(s) for some reason and was
not physically taxed by nursing one or two fawns all summer.
The more muscular whitetail is built like a running back a fast starter that tires quickly after about a quarter mile. The pronghorn's heart and lungs are larger than those of a whitetail, and contribute to its ability to run tirelessly at speeds up to 40 miles per hour for long distances, and much faster for short bursts.
Bill Jensen is a Game and Fish Department big game biologist.
bgame.zip (272K) -- Estimating Big Game Weights A Crash Course for the CuriousInstallation: Extract all files and open index.htm in a web browser.