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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

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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).

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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.

Over the past 40 years retired big game biologists Jim McKenzie and Jack Samuelson, as well as big game supervisor Roger Johnson and other North Dakota Game and Fish Department biologists, have collected weights and measurements on the six big game species found in North Dakota. By using the equations found in Table 1, and knowing the dressed weight — whole body or live weight minus internal organs — it is possible to derive a good estimate of an animal's live weight.

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.

These numbers also reveal differences in the make-up of each species. The internal organs of an average adult whitetail buck account for about 14 percent of its body weight. An average pronghorn buck would have 27 percent of its live weight allocated to internal organs.

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.

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Bill Jensen is a Game and Fish Department big game biologist.

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