Bear Damage Estimation 8

Last modified by pro on 2016/08/22 19:33

Bear Damage Calculator

               BEAR DAMAGE IN A FIELD
BearDamage1.png           Bear Damage Area Enlarged (below)BearDamage2.png
Wild animals damage crops.  A significant issue that occurs with farmers on a regular basis is the damage done by bears.  Bears get into fields of crops and in a little time produce a significant amount of damage.  Some states provide compensation for bear damage, and this calculator will help assess the real dollar impact (damage) done on a corn field due to bear damage.  To use the calculator, follow the steps indicated below.

vCalc Quick Guide (Companion Formulas)
 Calculator ButtonsDescription
Calculate Damaged Area
Calculate Length of sample row
Compute the Kernels per Ear
Yield of Damaged Area

Compute Value of Damage

Measuring Damage Value

The steps to compute the bear damage in real dollars is as follows:

  1. Measure the damaged area
  2. Estimated Yield of the area in bushels of corn
  3. Compute the dollar value of the damaged area.

Measure Damaged Area

The bears will get into a field and knock down crops.  They tend to do it in several areas, so you may have to repeat the process of measuring the area.  This process lets the farmer make a conservative estimate (in the farmer's favor) of the area damaged.   

  1. First identify the general areas of damage.  
  2. Then put four markers (posts or poles in the ground) that will create a four sided area surrounding each significant area of bear damage.  Label the corner markers 1, 2, 3 and 4.  (see diagram).  
  3. Then measure the distance between the markers along the outside.  These are sides a, b, c, and d in the diagram.
  4. Then measure the distance between corner 1 and corner 3.  This is the diagonal (D)
Example of two damaged areas.
X Area 1 Area 2 
 (a) 90 ft46 ft
 (b) 67 ft32 ft
 (c) 82 ft50 ft
 (d) 74 ft27 ft
 (D) 137 ft64 ft
Area: 0.12 acres 0.03 acres
 0.15 total acres of damage.

Make your measurement in feet, yards or meters.  The calculator supports all of these units.  With these measurements (a, b, c, d and D), CLICK HERE and enter your values.  This will compute the four sided area.  This is larger than the actual area, but not unreasonably too large.  Do this for all of the significant damaged areas.

The table to the right is an example of two damaged areas.  Compute the areas separately and add them together in the final corn yield calculations.

Estimated Yield

To estimate the yield potential of the damaged area, we need to compute the approximate bushels per acre in this part of your field.  To do this:

  1. Compute the length of a row that is a 1,000th acre sample.
  2. Take a Sample to compute an average.
  3. Estimate the Size of your Kernels
  4. Compute the yield of the damage area.

Compute the 1,000th acre sample

Next to the bear damage area, measure the width of the rows of corn.  Use the width (separation) of the rows and CLICK HERE.  This will tell you how long in the row is a 1,000th acre sample that will be used to estimate the bushels per acre in the bear damage area.  For example, your rows could be 30", and a 1,000th acre sample would be 17.4 feet long.                                   ROWS of KERNELSKernelCount.png KernelSizes.png

Take a Sample

  1. Walk along the sample row and count the number of ears of corn within the 1,000th acre sample. (e.g. 30 ears). 
  2. Then, go back through the row and pick five ears.
  3. Count the kernels on each ear.  CLICK HERE for a simple calculator to compute the kernels base on the rows and kernels per row. 

Estimate the Size of Kernels

Look at the kernels in the sample ears and make a rough gauge on the size of the kernels.  Use the diagram as a guide if needed.  These are used to estimate the thousands of kernels per bushel. Large kernels require fewer kernel to reach a bushel (80,000), Medium kernels require 90,000 to fill a bushel and small kernels require 120,000 kernels to make a bushel.

Compute the Yield

Use the number of ears in your 1,000th acre sample, the kernels per ear in your five ears and the approximate size of your kernels, CLICK HERE to compute the estimated yield in the bear damaged area.  For example, let's assume medium kernel sizes, and a five ear sample of (512, 466, 502, 470, and 499), and 30 ears of corn on our 1,000th acre sample.  Combine these numbers with 0.15 acres of damage, and we have a loss of 24.48 bushels of harvested corn.

Crop Value

Now that you have an approximation of the bushels of corn destroyed by the bears, there's one last step: calculating the value.  Fortunately grain futures, such as corn, are available on the open market.  At the time of this writing the USDA estimated a high value of corn to be $3.70 per bushel.  Use your volume of crop loss (e.g. 24.48 bushels) and the trading value of the corn (e.g. $3.70), and CLICK HERE.  This will compute the total loss due to bear damage.  In our example, it was $90.58.

Equations

  • Simple Corn Yield by KurtHeckman
  • Size of Garden (Area) by pro
  • Field Size Acres by KurtHeckman
  • Thousandth Acre Row by vCalc
  • Kernels per Ear of Corn by KurtHeckman
  • Corn Crop Value by pro

Constants

  • USDA Corn Price Projection (2016) by pro