How To: Spotlight Surveys on Your Ranch (According to TPWD)

If you've ever spent several late nights driving your ranch with a spotlight in hand, hoping to get an accurate count of your deer or exotics, you already know how much effort traditional spotlight surveys demand. While spotlight counts have been a long-standing method endorsed by Texas Parks & Wildlife Department (TPWD), they come with clear limitations. Now, a smarter, more efficient alternative exists: thermal drone surveys with Sky Senderos.

How to Conduct a Spotlight Survey (According to TPWD)

If you’re considering running a traditional spotlight survey on your property, Texas Parks & Wildlife Department (TPWD) outlines a specific method to help estimate deer populations. While effective under ideal conditions, this approach takes planning, patience, and a significant amount of late night hours.

Here’s a simplified version of TPWD’s spotlight survey process:

1. Choose Your Survey Route
   Select an all-weather road that offers good visibility on both sides. TPWD recommends constructing this route so that it samples different habitat types in proportion to the number of acres they represent on the property.‍
2. Mark Distance Intervals
   You’ll need to mark every 1/10 of a mile along your transect using odometer readings or GPS. These markers are used to record deer sightings and visibility range at each point.‍
3. Mark Distance Intervals
   You’ll need to mark every 1/10 of a mile along your transect using odometer readings or GPS. These markers are used to record deer sightings and visibility range at each point.‍
4. Schedule Multiple Surveys
   Conduct surveys three to four times between August and October, starting about one hour after sunset. Choose calm, dry nights—avoid rain, strong wind, or full moons, which can affect animal behavior.‍
5. Gather Your Equipment
   You’ll need at least two people (a driver and an observer), a spotlight with a strong beam (ideally vehicle-mounted), and a data sheet or app to log sightings. Binoculars are recommended to confirm species or sex.‍
6. Record Sightings and Visibility
   Drive at 5–10 mph. At each 1/10-mile interval, record how far you can see into the brush (up to 250 yards). Note the number of deer seen, their location (left or right side of road), sex, age class if possible, and any other wildlife observed.‍
7. Analyze the Data
   TPWD provides formulas and guidance to convert raw sightings into estimates of population density, sex ratios, and buck age structure. Results are best used year over year to spot trends, rather than be taken as absolutes. To start, divide the total number of deer into the total number of visible acres observed to determine the number of acres per deer on the route. For example: 1,260 acres (one spotlight survey route run 3 times with 420 acres of visibility) divided by 90 (total number of deer observed on that spotlight survey route run 3 times) = one deer per 14.00 acres. The estimated deer population for the ranch can then be estimated by dividing the total acres of the ranch by the estimated acres per deer figure. For example, the deer population estimate for a 5,000 acre ranch with a deer density of one deer per 14.00 acres is 357 total deer. An estimate of the number of bucks, does, and fawns in the population may then be determined by multiplying the total number of deer by the percent of all deer identified that were bucks, does, and fawns.
   
   

The Spotlight Count Struggle - And How Sky Senderos Can Help

Time-Intensive Process
Spotlight surveys aren’t a one-night job. It’s recommended to repeat the survey three to four times during late summer or early fall to gather meaningful data. That means multiple late nights in a row, often covering the same ground just to build a reliable population estimate. In contrast, a Sky Senderos thermal drone wildlife survey can be conducted in one night. 

Subjective Visibility Estimates
Survey results rely heavily on what the observers can see—and agree upon. Visibility is recorded every tenth of a mile and often varies due to terrain, brush, or weather. The entire process depends on human estimation of distances, shapes, and ere reflectivity, which leaves plenty of room for error. A thermal drone survey is able to provide a bird’s eye view of your property and cut through thick brush for increased visibility of your animals. 

Limited Detection Range
TPWD recommends that only animals spotted within a 250-yard radius be counted. Anything beyond that, or obscured by trees, brush, or terrain, doesn’t make it into the data. That limitation alone can lead to serious undercounts, especially in heavily vegetated properties. Sky Senderos’ pre-planned flight routes ensure we cover 100% of every property we survey, not leaving anything out of the data. 

Observer Fatigue and Error
After multiple nights of late-night surveying, observer fatigue sets in. Missed sightings, incorrect species identification, or double-counting become increasingly likely. The more tired the crew, the less reliable the data becomes, especially on large ranches where long nights are unavoidable. Our drones are able to record footage the entire time they’re in the air. This allows our team to go back and review everything we saw to make sure that your final report has minimal human error. 

Equipment and Manpower Requirements
Spotlight surveys require more than just a flashlight. You’ll need a vehicle modified with mounted lights, at least two people (driver and observer), and often some coordination with TPWD staff. For many landowners, it’s a logistical headache that takes time away from daily ranch operations. Sky Senderos not only brings all of the necessary equipment for flying the survey and allowing observers to watch along, but we also handle the legal paperwork through TPWD ahead of time. All that a client needs to do is schedule a date and provide a way for us to get on the property. 

Not Ideal for All Properties
TPWD specifically advises against using spotlight surveys on smaller tracts or in dense habitats where visibility is limited. That makes the method a poor fit for many South and Central Texas ranches, where thick brush or extreme topography dominate the landscape. While there are some properties that may be unsuitable for a thermal drone survey as well, that list is significantly smaller thanks to the advanced imaging technology that can penetrate thick brush.

More Efficient, Less Stress—for You and Your Wildlife

Sky Senderos thermal drone surveys are conducted by our certified operators and require no late-night effort from the landowner. You won’t need to prep vehicles, chase conditions, or gather multiple nights of data. And because drones fly quietly and don’t shine lights into the brush, your animals aren’t spooked or stressed, yielding a more accurate picture of what’s really out there.

They’re especially valuable for detecting elusive species like hogs or exotics that rarely appear during spotlight runs.

Take the Guesswork Out of Wildlife Counts

Spotlight surveys still have a place, but they require dedication, planning, and clear weather. Thermal drone surveys offer a faster, easier, and more accurate solution, especially for busy landowners who want the data without the disruption.

At Sky Senderos, we specialize in helping landowners get more accurate, actionable wildlife data using cutting-edge drone technology. Let us handle the late nights, so you don’t have to.

Ready to count your animals the smarter way? Request a FREE quote today for your thermal drone wildlife survey.