A Zero Is Data. Keep Sightings, Sign, Camera Effort, and Weather Apart.
A pin labeled "deer" after a walk, a week of cameras, and a pile of pellets mixes at least four kinds of record. This guide shows how to log live sightings, sign, camera effort, and weather in separate columns, why an empty walk is a row worth keeping, and where the arithmetic has to stop. It also lists the land-manager camera rules we read at the source, which differ by agency and state.
IEmpty walks
The 2002 MacKenzie paper in Ecology states the premise plainly: nondetection of a species at a site does not imply that the species is absent unless the probability of detection is 1. The model it proposes can handle missing observations.
The USGS fact sheet Occupancy Models to Study Wildlife (Fact Sheet 2005-3096, September 2005) puts that in field terms. Wildlife is rarely detected with perfect accuracy, so an observed absence means either the species was present and missed or it was truly absent. Detectability can differ among sites and among survey days, with weather as one example, and the proportion of sites where a species is detected will always underestimate true occupancy when detection is imperfect. The models work from repeated observations of each site, recorded as detected or not detected on each survey, and the sheet tells investigators to record weather conditions during each survey.
Two rules follow for a hunter's notebook. Log the zeros: a walk with no deer is a detection history of 0 and a reason to keep the pin, not delete it. And treat failed gear as missing data instead of a zero, since a camera that died on night two did not sample nights three through seven.
Do not turn those rows into a home-made occupancy figure. The models estimate two quantities, the probability that a site is occupied (ψ) and the probability of detecting the species when it is present (p). The fact sheet's method rests on sites chosen by probability-based sampling and on assumptions such as independent sites and a closed occupancy state. In our reading, a notebook of favorite spots does not meet the sampling requirement. Store the histories and leave ψ and p to the papers. FDR's deer movement scores guide applies the same test to percent scores of a hunting day.
IIFive records
Each of these gets its own column, and none of them may stand in for another.
- Live sightings. Record the date, start and end time, place, observer, and the number of deer seen on that visit. The count belongs to that visit and says nothing about unique animals across days. UF/IFAS's classroom camera guide says white-tailed deer are primarily crepuscular, so the clock times at both ends of a sit are worth writing down.
- Sign. Tracks, pellet groups, rubs, scrapes, and browse are indirect detections and never live animals. In a capture-recapture study on Arnold Air Force Base, Goode and colleagues (Wildlife Biology, 2014) searched 703 plots of 10-meter radius in Tennessee from 11 to 22 January 2010 and collected 352 pellet-group samples from 197 plots over five two-day intervals. Using only the freshest pellets, they recorded 140 captures of 33 animals. The step worth copying is the screening, because not every pellet group counted. Class your sign as fresh, old, or unknown and leave unknown as unknown. The abstract gives no decay rate, so this log has no rule for turning a pellet group into hours since deposition.
- Camera events. UF/IFAS says modern camera traps trigger on a combination of motion and heat sensors, often last several weeks or more on one set of batteries, and, run for a few weeks, can give an idea of what species are present and how common they are. Log camera-nights as 24-hour periods when the unit was working, and count photo events instead of deer, because we do not assume a still image identifies an individual. Sun or wind on plants can trigger a camera, and high sensitivity produces many photos of swaying vegetation, so mark those frames as false triggers. UF/IFAS also says to walk in front of the camera when you set it and again when you collect it to confirm it responds.
- Weather. Write precipitation, wind as you judged it (calm, breezy, strong), temperature from a thermometer or the camera's data band if it prints one, and sky. Leave unknown values blank and do not back-fill from a forecast you did not record. FDR's wind forecast guide explains why forecast wind arrows get less reliable in calm, clear, cold conditions, which is one reason to record the wind you felt.
- Nondetection and missing effort. For every visit and every camera-night, mark one of three states: detected, not detected, or not sampled. UF/IFAS says cameras fail when memory or batteries run out or the unit malfunctions, and each of those nights belongs in the third state.
IIIWorked example
These numbers are invented to show the arithmetic. They are not field data.
Three cameras ran for seven nights on a woodlot where the owner had given permission. Cameras A and B worked all seven nights. Camera C failed after two, so its last five nights are missing and not zeros. Operational camera-nights are 7 plus 7 plus 2, which is 16. Camera A logged 4 deer events, B logged 2, and C logged 0, for 6 events in 16 camera-nights, or 0.375 events per camera-night. Two walks of 90 minutes each add 180 minutes of foot effort. The first, in light rain under an overcast sky, found no live deer and three pellet groups, one classed fresh and two unknown. The second, on a clear day, found one adult doe and one pellet group of unknown age.
Read 0.375 as detections per unit of effort and nothing more. It does not estimate occupancy or abundance, and it says nothing about the next sit.
The rows below come from that example. Copy the header into a notebook or spreadsheet.
| Date | Place | Permission | Method | Effort | Weather | Class | Sign freshness | Count and notes |
|---|---|---|---|---|---|---|---|---|
| 8 Oct | South trail | yes | walk | 90 min | light rain, overcast | none | n.a. | 0 live deer |
| 8 Oct | South trail | yes | walk | 90 min | light rain, overcast | sign | fresh | 1 pellet group |
| 8 Oct | South trail | yes | walk | 90 min | light rain, overcast | sign | unknown | 2 pellet groups |
| 9 Oct | Camera C | yes | camera | 0 camera-nights | unknown | missing | n.a. | failed after night 2; nights 3 to 7 missing |
| 13 Oct | South trail | yes | walk | 90 min | clear | live | n.a. | 1 adult doe |
A camera-night with no deer is "none". A dead camera is "missing". A pellet group is "sign" and never "live".
IVPermission and rules
Permission comes before the first pin. The UF/IFAS classroom guide says to always obtain permission before placing cameras on property that does not belong to you. FDR's permission playbook covers the ask, and its landowner name check covers verifying the owner of record before you knock. If you post a camera image, the UF/IFAS camera trapping guide warns that any coordinates, addresses, or names in the data band must be removed before you upload it.
Camera rules belong to the land manager, and they differ. The four below are from the text we retrieved at the source. This is not legal advice. Rules change, so read the current text before you hang a camera.
- Wisconsin Department of Natural Resources lands. NR 45.04(3)(w), retrieved from the Wisconsin Legislature site on 29 September 2026, says no person may place and leave trail cameras unattended overnight on department lands unless three conditions are met. The camera must be permanently and legibly marked in English with the operator's name and address or department customer identification number, clearly visible on the outside of the camera without needing to move or adjust it. Placement, use, or installation must not damage vegetation or other department property. And the camera's location and entire available field of view must stay in areas where hunting is allowed and outside designated use areas, including designated trails, beaches, campgrounds, buildings, roads, water access points, and parking areas. A note in the code says placement is at the operator's own risk and the department is not responsible for theft or damage.
- Kansas Department of Wildlife and Parks lands. K.A.R. 115-8-25, published in the Kansas Register on 6 April 2023 and effective 21 April 2023, says no person shall place, maintain, or use a trail or game camera on department lands, or use any images or video from one, including location, time, or date, for any purpose on department lands and waters, including walk-in hunting areas (WIHA) and integrated walk-in hunting areas (iWIHA). It excepts cameras owned by the department or a designated agent and used for department operations or research. We read the 2023 text and did not check for later amendments.
- Arizona. R12-4-303(A)(5) makes it unlawful to place, maintain, or use a trail camera, or images, video, or data from one (to include location and time), for the purpose of taking or aiding in the take of wildlife or locating wildlife for that purpose. The Arizona Game and Fish Department's 2026 to 2027 hunting regulations add that scouting prior to a hunt also falls under the definition of take, and list trail or scouting cameras among the items prohibited on national wildlife refuges in the state.
- National Park Service lands. 36 CFR 2.22(a)(2), shown as current on the eCFR as of 25 September 2026, prohibits leaving property unattended for longer than 24 hours, except in locations where longer periods have been designated or under conditions the superintendent sets. Paragraph (b)(2) lets the superintendent impound unattended property at any time if it interferes with visitor safety or orderly management of the park area or threatens park resources. Arizona's booklet applies the 24-hour limit to game cameras on NPS-managed land in Grand Canyon-Parashant National Monument.
Where a camera is legal, it is a different observation method from a sit. Log it as camera effort and not as a walk, and keep the two out of the same denominator.
VComparing days
Compare live sightings against live sightings after similar minutes afield, camera events against camera-nights that ran, and fresh sign against fresh sign. UF/IFAS's classroom guide makes the point for cameras: to compare locations, use the same angle and height at each one. When the weather differed, say so in the row.
The log cannot tell you how many deer use a property, because event counts are rows and not animals. It will not age a track to the hour, and it will not carry one state's camera rule into another. When you saw nothing, keep the zero.
- Regulation text quoted here was read on the dates stated in the guide. Rules change; confirm current rules with the land manager or state wildlife agency before you place a camera or scout.
- Nothing here guarantees deer activity or hunting success.
Fully Drawn Research is an independent data analysis desk, not affiliated with the Illinois Department of Natural Resources, the Illinois Department of Transportation, or any mapping or outfitting provider. This guide describes a record-keeping method and quotes public regulations; it is not legal advice.