Tiger Demographic

[Dr Panthera]

In previous discussions with a few esteemed members of our forum I noticed that their understanding of tiger population demographics and variation among different population is focused on certain habitat, the main point was the variation of the percentage of breeding adult tigers in different habitat; in areas with quality habitat and adequate prey base tigers establish territories and breed continuously and have more cubs, consequently the percentage of juvenile tigers ( cubs, large cubs, and sub-adults) is high and juveniles outnumber adults, conversely in poor habitat tigers breed less, have less cubs, and their cubs and sub-adult survival is poor and adults may outnumber them.
A great study on this issue was authored by Barlow, McDougal, Smith, Gurung, Tamang and others based on long term data from Chitwan Royal National Park in Nepal.
The authors classified tigers as breeding and non-breeding, breeding tigers are resident males and females who established territories and secured resources for successful reproduction.
Non-breeding tigers were classified as cubs (0-1 year) large cubs (12 - 18 to 24 months the age of dispersal ) pre-territorial transient animals ( sub-adults looking to establish a territory ) and post-territorial transient ( adults that were forcefully ejected from their territory by stronger rivals).
The data showed a stable number of breeding adults per study area...a 100 km2 area constantly had 8 breeding adults 1-2 males and 6-7 females , the litter size and survival of cubs was also somewhat stable, the biggest variable was the transient tigers.

Resident males per population          0-15%          Mean 7 %
Resident females                             23-67%        Mean 35%
Cubs                                              0-65%          Mean 30%
Large Cubs                                     0-55%          Mean  18%
Transients ( pre and post-territorial)  0-40%          Mean  10%

Consistent with large polygamous mammals male tigers need to be of a number small enough to curb competition and large enough to ensure genetic variability
Breeding female tigers are the most important component of tiger society and hold the key to the species success. Their number is the most important predictor of survival in any tiger habitat census.
Juveniles ( cubs and large cubs ) are the future of tigers and their survival to adulthood and success in establishing territories is very complex and dependent on the particular tiger demographics in the area, resources, and conservation.
Transients young and old live stressful lives ..chased by territory holders, pushed towards fringe habitat, get in conflict with man and sadly die frequently from such encounters. Reply