How we count, and what a count can't tell you

Equipment

Surveys fly on an Autel EVO II Dual 640T, which pairs a 640 × 512 thermal sensor with a high-resolution zoom camera. The thermal sensor finds heat; the zoom camera confirms what it is. Daylight habitat imagery uses a pair of DJI Air 3S aircraft.

Before each season we check the thermal camera against known temperatures and log aircraft maintenance in our flight records.

Flight design

We draw your survey boundary, then lay parallel transects across it. Spacing is set so the thermal camera's ground footprint overlaps between neighboring lines at survey altitude, usually about 300 to 400 feet above ground. The aircraft flies each line at a steady speed while the full thermal feed is recorded.

Every survey keeps its flight plan on file. Repeat surveys fly the same lines so results compare year to year.

Timing and conditions

Thermal cameras see deer by the difference between body heat and the background. That difference is largest when the ground is cold and the canopy is bare. Full counts therefore fly:

• December through mid-March, after leaf-off
• In the last one to two hours before sunrise, when the ground is coldest
• Below about 40 °F, with light wind and no rain, snow, or fog

Research supports this. As spring green-up spreads, a growing share of deer are hidden in cover where they can't be counted, and hot weather sharply reduces detection. Summer pattern flights still work, but we fly them in the coolest hour and report wider ranges.

Confirmation and classification

Rocks, stumps, and other animals can hold heat. Every candidate is checked on the zoom camera before it is counted. Each confirmed deer is tagged with GPS position and time, and classified as antlered, antlerless, or unknown. Antlered status is recorded only when antlers are visible; by late winter many bucks have shed, so “unknown” is honest, not a gap.

Detections we can't confirm are marked “verify” on the map and left out of the observed count.

Avoiding double counts

Deer move. When the same group could appear on two neighboring transects, we compare GPS positions, timing, group size, and direction of travel, and count the group once. Movement we can't resolve is reported, along with the effect it could have on the count.

Detection adjustment

No aerial method sees every deer. Published field studies of thermal drone surveys report detecting roughly 56% to 92% of deer present, depending mostly on cover. We report two things:

• Observed count and density: what we saw and confirmed
• Detection-adjusted range: the observed count divided by the low and high detection rates that fit your cover and conditions

The report states which detection rates we used and why. A repeat flight within 14 days narrows the range. Detecting small year-to-year changes with confidence takes repeated surveys; Pennsylvania research found about three surveys a year are needed to detect a 20% change with 80% confidence, and we'll design for that if your decision depends on it.

Disturbance and ethics

• We fly high and steady, and never descend on, follow, or haze animals.
• We use no spotlights. Thermal sensing is passive.
• In fawning season (May–June) we map from altitude and never approach bedded fawns.
• If deer react to the aircraft, we note it in the report.

Rules we follow

• FAA Part 107. Dale holds Remote Pilot Certificate #5250269. Night flights use anti-collision lighting and follow Part 107 night rules. We request airspace authorization near airports.
• Permission. The FAA regulates the airspace, so a flight that follows FAA rules doesn't legally need a landowner's permission to pass over their land. Taking off and landing do, and we launch and land only where we have permission. As a company policy, we also survey only land whose owner or manager has agreed. State Game Lands require written Game Commission authorization, and many county and state parks restrict drones; we handle those requests.
• No hunting assistance. The Pennsylvania Game Commission treats drone use in any part of hunting, including scouting and recovering deer, as unlawful. We survey for counts and management only, and we never share live or recent wildlife locations with hunters or trappers.

Your data

You own your survey results. Locations stay confidential and are shared only with people you name. On request, we delete raw footage after delivery and keep only the report. Privacy details.