The National Pheasant Plan model

Citation:  Midwest Pheasant Study Group.  2013.  National wild pheasant conservation plan.  N. B. Veverka (ed.).  Association of Fish and Wildlife Agencies.  111pp.

This model was constructed by the Midwest Pheasant Study Group (the precursor organization of the National Wild Pheasant Technical Committee) to estimate the habitat needed to meet state-specific pheasant harvest goals identified in the National Wild Pheasant Conservation Plan.  It established a general approach to the problem and allowed individual states to make adjustments to that approach to fit their specific circumstances.  The resulting state-specific habitat needs were then aggregated to estimate "national" acreage goals, while recognizing that not every state in the pheasant range participated in the modeling exercise.


Model construction

The model deduces a mathematical relation between state-level nesting habitat acreages and pheasant harvest estimates.  Based on the literature, general nesting habitat categories were defined as Conservation Reserve Program (or similar) grasslands, small grains, alfalfa, grass hay, and pasture.  USDA CRP and crop acreage data for these categories were obtained for a ten-year reference period for each state, as well as state pheasant harvest data for that same period.  The model assumes that a state’s pheasant population nests in these habitats in proportion to their availability, but allows nest success estimates to vary by habitat type.  An equation to relate the number of acres of a given habitat type needed to produce one harvested wild rooster in a given state was constructed as follows:

Calculating other response variables

To calculate the number of additional acres of a given habitat needed to reach the state's pheasant harvest goal, the acres per harvested bird for that habitat is multiplied by the difference between the current and the desired pheasant harvest.  To calculate the acres of habitat needed to produce a fall (pre-hunt) rooster, the acres per harvested rooster is multiplied by the estimated harvest rate (i.e., the proportion of fall roosters that are harvested).  The number of acres needed to produce a fall (pre-hunt) pheasant is the acres per fall rooster multiplied by the estimated proportion of the fall (pre-hunt) population that are roosters.


Model estimates

Estimates of the acres of a particular habitat type needed to produce a harvested rooster vary among states due to underlying differences in habitat productivity across the pheasant range, state-specific estimates of nest success, the series of years used as a reference period, and which vegetation types met the definition of nesting habitat (e.g., many states did not consider pasture to be a significant nesting habitat type, thus reducing their habitat categories from five to four).

From a policy standpoint, the relation between habitat acreage and harvest is of particular interest for Conservation Reserve Program grasslands.  Model results for CRP as reported in the National Plan are given below.  They are based on a 10-year reference period chosen by each state during a fifteen-year window (1990-2005); states chose reference periods that best represented that era's habitat and harvest conditions.  Estimates should be considered averages for each state; smaller-scale relations would vary by landscape composition, local habitat conditions and configurations, etc.  Results for other habitats and response variables are presented in Appendix C of the National Plan.