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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


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).

Elk

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.

Mule deer    Pronghorn
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.

White-tailed deer    Moose
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.

Bighorn sheep


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