What it does
Camera traps take thousands of photos, most of them bursts of the same animal or empty frames set off by wind. This page helps you get from a folder of photos to the numbers a survey needs, without uploading anything:
- reads the date and time from each photo’s EXIF data,
- groups photos taken close together at one camera into events, so a burst of ten photos is tagged once,
- lets you tag species, count and behaviour with one key each, and add notes,
- works out independent detections, detections per 100 trap-nights (the relative abundance index, RAI), naive occupancy and activity by hour,
- exports the photos with their tags, and the detections, as CSV.
Your photos stay on this device. They are read by your browser and never uploaded; the page works offline once loaded.
How to use it
- Press Choose a folder and pick the folder of a survey. Each sub-folder is taken as one station (camera); photos picked one by one go to the station named in the box.
- Set the event gap (photos closer than this at one station form an event; 5 minutes suits most bursts) and the independence interval (photos of one species at one station closer than this count as one detection; 30 minutes is common, some studies use 60).
- Type your species and behaviours. Keys 1 to 9 tag the species in order, 0 marks an empty event, Q W E R T set the behaviour, + and − change the count, the arrow keys move between events, N jumps to the next untagged event and Backspace clears a tag.
- Type the real number of trap-nights for each camera (the first guess is the number of days from its first to its last photo).
- Read the summary table and the activity chart, and download the CSVs or a report as PNG, PDF or Word.
Worked example
The page opens with a made-up survey: three cameras over two weeks, already tagged. The summary reads “70 detections of 5 species in 40 trap-nights” (14 + 14 + 12 nights). Deer have the most detections (23, an RAI of 57.50 per 100 trap-nights); the badger was never seen at camera C, so its naive occupancy is 2 of 3 stations, 0.67. Choose Fox under “Activity of” and the chart shows detections only between 21:00 and 03:59, a nocturnal pattern; birds show only in daylight.
Change the independence interval from 30 to 60 minutes and visits that came back within the hour merge, so the number of detections can only stay the same or fall.
Tips
- Check the camera clocks before a survey and note any that were wrong; the times here are the camera’s own, with no time zone applied.
- RAI depends on camera placement, trigger speed and the interval you choose, so compare it only between surveys done the same way.
- Naive occupancy ignores animals that were present but not photographed. For true occupancy you need repeated surveys and a detection model (for example in R with the unmarked package).
- The photos CSV has one row per photo with its event and detection number, ready for R or a spreadsheet.
FAQ
Are my photos uploaded? No. They are read on this device. Only the file name, size and time are used to remember tags, and only in this browser.
Where are my tags kept? In this browser’s local storage on this device, by file name, size and time, but only after you tick “Remember my tags in this browser” (it is off at first, so nothing is saved unless you ask). They come back if you open the same photos again. Untick “Remember my tags in this browser” to stop and delete them, or press Clear saved tags.
My photos have no date. Some cameras or editing programs strip EXIF data. The page then uses the file’s date, which may be the date it was copied, and says so in the caption and the CSV.
Why is one detection counted as the most animals in any photo? Animals in a burst are usually the same individuals photographed again, so adding them up would count them twice.
Where the numbers come from
- The EXIF reader, event grouping, independent detections (a gap rule applied per station and species), the relative abundance index (detections per 100 trap-nights) and naive occupancy are written by fibub. The tests check the EXIF reader against exifread and Pillow on JPEGs made with Pillow, and the detection counts and summaries against the same rules in pandas on made-up records.
- EXIF 2.3 (JEITA CP-3451) tags DateTimeOriginal, DateTimeDigitized and DateTime: open specification.
- The example survey (three cameras, species, times and counts) is made up by fibub; its pictures are drawn placeholders.
- Photos you open are read on the page only and never uploaded. Tags are kept in this browser only if you tick the box (off at first).
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.