Interbirth interval and litter size of free-ranging Bengal tiger (Panthera tigris tigris) in dry tropical deciduous forests of India

Abstract

We studied the interbirth interval (IBI) and litter size of the population of free-ranging Bengal tigers (Panthera tigris tigris) in dry tropical deciduous forests in Ranthambhore Tiger Reserve (RTR), Rajasthan, and Pench Tiger Reserve (PTR), Madhya Pradesh, between April 2005 and June 2011. Data on 15 breeding females in RTR and nine breeding females in PTR were collected using camera trapping, direct observation and radio-telemetry. The mean ± standard error of IBI (months) in RTR was 33.4 ± 3.7 and in PTR was 25.2 ± 1.8. A significant difference was observed between the mean IBI of tigresses in RTR and those in PTR (df = 9, P = 0.04). The estimated mean litter size in RTR was 2.3 ± 0.1 and that in PTR was 2.9 ± 0.2. There was a significant difference between the litter size in RTR and that in PTR (χ 2 = 12.04, P = 0.017, df = 4). Since RTR and PTR are the important source populations of tigers in the Western and Central Indian landscapes, we propose that the tigers in these reserves be monitored, particularly for reproductive traits that are essential for understanding aspects of their population ecology.