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Drive counts as a method of estimating ungulate density in forests: mission impossible?
Acta Theriologica
|July 19, 2011
Summary
Drive counts for estimating deer populations are more accurate at higher densities. However, for precise estimates (within 10%), drive counts are insufficient, but acceptable for less accurate estimations (within 20%) at higher densities.
Area of Science:
- Wildlife Ecology
- Population Dynamics
- Forest Management
Background:
- Drive counts are commonly used for estimating forest deer populations.
- The accuracy of drive counts is influenced by methodology, deer density, and social organization.
- Understanding these influences is crucial for effective wildlife management decisions.
Purpose of the Study:
- To evaluate the impact of various factors on the accuracy of deer drive counts.
- To assess the suitability of drive counts for informing deer population management.
Main Methods:
- Utilized a computer simulation model for 'virtual experiments'.
- Simulated red and roe deer populations based on Polish forest data.
- Analyzed effects of block size, forest proportion, deer density, aggregation, and spatial auto-correlation on count accuracy.
Main Results:
- Count accuracy increased with higher deer density for both species.
- Accuracy decreased with increased demographic or spatial aggregation.
- Density had a greater impact on accuracy than aggregation.
- Increasing the proportion of forest counted improved accuracy, but with diminishing returns relative to effort.
Conclusions:
- Drive counts are inadequate for high-accuracy deer population estimates (within 10%).
- Drive counts can provide reliable estimates (within 20% or more) at higher densities (over 5-7 deer/100 ha).
- Adjusting counting blocks offers limited improvements for low-density, aggregated populations.
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