ON THE EDGE OF EXTINCTION - A - THE TIGER (Panthera tigris)

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The influence of reproductive status on home range size and spatial dynamics of female Amur tigers

Abstract:

In populations of wild felids, social status is one of the most important factors shaping home range size and spacing patterns. For female Amur tigers (Panthera tigris altaica), we documented significant changes to the structure of home ranges and core areas during cub-rearing. We used VHF telemetry data collected over 18 years in Sikhote-Alin Biosphere Reserve, Russia, to assess the following: (1) home range and core area size and (2) spatial shifts with and without cubs and (3) spatial shifts associated with philopatry. Home range and core area sizes of females collapsed by 60% after birthing, with recovery requiring 18 months. We hypothesized that usurpation of temporarily abandoned territory by other females during cub-rearing was a possibility, but aside from philopatry, we did not observe a loss of territory or evidence of competition for space. Home range boundaries changed little during cub-rearing but shifting core areas revealed that females were using different segments of their home range while rearing cubs, contradicting the notion of a single, most important core area for breeding females. Our results support two hypotheses of space use by large carnivores: that adult breeding females achieve higher reproductive success by maintaining a home range just big enough to feed herself and her offspring, and a second hypothesis that females expand home range size when space is available to allocate land to daughters. We suggest that these hypotheses are not mutually exclusive, but explain patterns of space use by female felids under different demographic conditions. Reply