This is the first of a series on tiger population connectivity in a changing landscape.
Tigers (Panthera tigris) inhabit thirteen countries across Asia, but they currently occupy only 7% of their historical range. Recent estimates suggest that as few as 3,200 tigers may remain in the wild. Although the accuracy of tiger population estimates is a topic of scientific debate, widespread evidence supports a large-scale decline in tiger numbers over the past several decades, driven primarily by habitat loss and fragmentation, poaching, and a reduction in available prey.
Today most tiger populations are limited to small forested protected areas surrounded by human-dominated landscapes. Tigers may not commonly disperse across large areas (e.g., >20 km wide) of agricultural or urbanized landscapes, but they have been known to travel through broad expanses of degraded forests. One tiger, radio-collared for GPS tracking of its movement, completed a 450 km journey in India through a mix of agricultural lands and forest fragments over a four-month period. Individual tigers have been known to travel more than 690 km between protected areas.
A wide range of management strategies can be used to support tiger conservation. Most recently, efforts have focused on protecting and increasing tiger populations at “source sites” such as protected tiger reserves, landscape-level planning to promote movement of tigers through human-dominated areas outside of protected reserves, and reducing illegal poaching of tigers and their prey. In planning for connectivity of tiger populations, satellite images can be combined with tiger movement data from radio telemetry or genetic studies to identify potentially important tiger dispersal corridors.
As we look for management strategies that work for tiger conservation, one such effort is underway in the country of Bhutan. In the spring of 2015 it was announced that the nation’s tiger population may be one-third larger than previously thought, with a current estimate of 103 individuals. Tigers are expected to thrive under a constitutional mandate that ensures that at least 60% of the country’s land area will remain under forest cover forever. Ten protected areas (five national parks, four wildlife sanctuaries, and one nature reserve) are linked by a network of nine biodiversity corridors, ensuring a permeable landscape for the survival of tigers and other wide-ranging species.
Next up: Challenges for tiger population connectivity within the Myanmar-Thailand forest complex, a guest blog with Nirmal Ghosh.
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Bhutan Foundation Web Site: www.bhutanfound.org
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