Count burrow entrances in your garden plot, then enter area and correction factors. Use visibility and detection to account for hidden or missed burrows.
| Observed Burrows | Active Burrows | Area (m²) | Visibility | Detection | Corrected Density (burrows/ha) | Severity |
|---|---|---|---|---|---|---|
| 18 | 10 | 250 | 0.85 | 0.90 | 94.12 | High |
| 6 | — | 400 | 0.95 | 0.95 | 16.62 | Moderate |
| 2 | 1 | 300 | 1.00 | 0.90 | 7.41 | Moderate |
1) Corrected burrow count
CorrectedBurrows = ObservedBurrows ÷ (VisibilityFactor × DetectionProbability)
2) Density per hectare
Density(burrows/ha) = CorrectedBurrows ÷ SurveyArea(ha)
- Mark the survey boundary and measure the area.
- Walk the plot in lanes and count burrow openings.
- Optionally record active burrows using fresh signs.
- Estimate visibility based on vegetation and soil cover.
- Set detection probability from your search method.
- Press Calculate to see density and severity.
- Use CSV/PDF downloads for logs and treatment plans.
- Compare repeated surveys across seasons for trend tracking.
- Use consistent methods when comparing two garden zones.
- Adjust thresholds to match your crop sensitivity and tolerance.
- Combine density results with damage checks for best decisions.
Start by defining one survey unit, such as a bed block or lawn strip, and measure its area. Walk the unit in straight lanes, scanning both edges and the center. Note features that attract burrowing, including mulch piles, compost, shed bases, and drip lines. Consistent boundaries and lane spacing make later comparisons reliable.
Observed burrows are the openings you can see, but cover and clutter can hide entrances. The visibility factor represents what is realistically exposed, while detection probability reflects how thoroughly you searched. Corrected burrows equal observed burrows divided by the product of these two factors, producing a more comparable estimate across different conditions.
Example: Observed burrows 18, active burrows 10, area 250 m², visibility 0.85, detection 0.90. Corrected burrows = 18 ÷ (0.85×0.90) = 23.53. Area in hectares is 250 ÷ 10,000 = 0.025 ha. Corrected density becomes 23.53 ÷ 0.025 = 941.2 burrows/ha. If burrows per rodent is 1.5, the plot-level rodent estimate is about 15.7.
Thresholds convert density into action categories. Set “Low” where monitoring and habitat cleanup are sufficient, “Moderate” where targeted exclusion and localized treatment are justified, and “High” where integrated control is needed. Keep thresholds consistent during a crop cycle, then refine based on observed damage and recovery after interventions.
Repeat surveys at similar times and after major changes such as irrigation adjustments, harvesting, or soil cultivation. Export results to share with teams and to compare zones over time. Combine density with active-burrow notes and plant damage checks to prioritize the most vulnerable areas and verify control effectiveness.
It standardizes burrow counts by area, helping you compare beds, identify hotspots, and track whether activity is rising or falling after control actions.
Use 1.00 for bare soil, 0.85 for light cover, and 0.70–0.80 for heavy mulch or weeds. Apply the same logic each time you resurvey.
Search speed, lane spacing, lighting, and ground clutter. Slower lane walks with overlapping scan zones increase detection, while quick passes reduce it.
Active burrows reflect current use and help target treatments. Fresh soil, tracks, droppings, and recent feeding damage are common field indicators.
No. Burrows per rodent varies by species and conditions. Use the estimate for planning and trend checks, not as a precise population count.
Yes. Enter your preferred unit and the calculator converts it internally. The output is standardized to burrows per hectare for comparison.
During active problems, resurvey every 1–2 weeks and after major changes like tilling or irrigation shifts. For stable areas, monthly checks work well.