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  4. 1997
  5. March

How Many Deer Are Too Many?

Posted Mar. 1, 1997

Without records, most land managers are unable to tell. Livestock managers are trained to monitor forage availability and body condition of their herd. Except in extreme cases, deer forage conditions are subtle, and body condition observations are limited to the check station.

Indicators of the balance between deer numbers and forage conditions include fawn/doe ratios, antler characteristics (especially of yearling bucks), and deer body weights. Like most deer population parameters, trends over time are more important than any variable in a given year.

We have been monitoring these trends with spotlight surveys and harvest records at the Red River Demonstration and Research Farm (RRDRF) since 1993. Two trends for which we have adequate samples in all years are included for reference. Figure 1 shows the relationship between fawn crop (fawns/doe) and deer density over four years. Figure 2 depicts trends in yearling doe weights and deer density. Both indicators show a negative response to increasing deer density.

Just as open cows hurt the profitability of a cow herd by using forage without producing anything, unproductive does use forage that would otherwise be available to bucks. When doe weights are trending down; buck weights and antler mass are likely to follow. To reverse these trends, we need to reduce deer numbers, improve habitat conditions, or both.

Trophy animals, be they bucks or bass, are produced from a surplus of resources per individual. More deer are not necessarily better.