Study

Reproductive parameters of wild female Amur (Siberian) tigers (Panthera tigris altaica)

Kerley, L. L.; Goodrich, J. M.; Miquelle, D. G.; Smirnov, E. N.; Quigley, H. B.; Hornocker, M. G.

Journal of Mammalogy, 2003

Peer-reviewedlongitudinal studywild

What they did

Radio-collared female Amur tigers were followed through successive breeding attempts, recording litter size, cub survival, the interval between litters and the age at which daughters became independent.

Studied in: Panthera tigris
Sample size: radio-collared females followed through successive litters

What they found

Litters average around two to three cubs, cubs stay with their mother for roughly eighteen months to two years, and a female produces a litter only every couple of years at best. Cub mortality before independence is high, and a female’s lifetime output of surviving young is small.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Wild Amur tiger reproductive rates are low and cub survival is the parameter to which population growth is most sensitive.

How NatureHQ reads it

The arithmetic here is what makes tiger conservation hard and is rarely spelled out. A tigress raising a litter is committed for around two years, so losing one adult female removes far more than one animal from the population. That is also the answer to why populations recover so slowly even when protection works.

Limitations

The most northerly population, with the harshest conditions and the largest ranges; tropical rates are higher.
Cub deaths are often inferred from a cub ceasing to be detected rather than observed.
Poaching removed collared animals during the study, truncating reproductive histories.