Study
Estimation of tiger densities in India using photographic captures and recaptures
Karanth, K. U.; Nichols, J. D.
Ecology, 1998
Paired camera traps were placed along tiger travel routes to photograph both flanks of any animal passing. Individuals were identified from their stripe patterns, and the resulting capture histories analysed with capture–recapture models that estimate how many animals were present but never photographed.
- Studied in
- Panthera tigris
- Sample size
- camera-trap surveys at four Indian sites
Tiger density can be estimated with stated uncertainty from photographs alone, without capturing or handling any animal, because individuals are identifiable and the models account for animals missed.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Photographic capture–recapture provides a rigorous, repeatable basis for tiger population estimation, replacing methods that assumed every animal present would be detected.
How NatureHQ reads it
The reason to explain this method on a tiger page is that it replaced a much worse one. Tiger numbers were previously produced by counting pugmarks and assuming each track was a different animal — a procedure with no way to know what it had missed. What changed was not better cameras but the willingness to model non-detection, and the resulting numbers were often lower. A method that produces smaller numbers than the one it replaces has a hard political road, and this one had it.
- Requires enough photographs of enough individuals; sparse populations remain hard to estimate.
- The area a trap array effectively samples must be estimated, and that choice affects density substantially.
- Assumes stripe patterns are correctly matched, which later work automated to reduce observer error.
The count that starts by admitting what it did not see
How many tigers are in a forest, when you cannot possibly see all of them?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Published by: Wiley journalsPublished in a Wiley journal.
doi.org/10.1890/0012-9658(1998)079[2852:eotdii]2.0.co;2
This reference was resolved automatically against Crossref on 2026-08-11.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-11.