Effects of Roads and Human Disturbance on Amur Tigers.

Abstract

Understanding the effects of human disturbance on endangered wildlife populations is critical to their conservation. We examined the effects of roads and human disturbance on the survivorship and foraging efficiency of Amur tigers ( Panthera tigris altaica) on and near Sikhote-Alin State Biosphere Zapovednik, Primorye Krai ( province), Russia. To evaluate the effects of roads, we estimated survivorship of radiocollared tigers and their cubs living in three types of areas: (1) areas with primary roads, (2) areas containing secondary roads, and (3) areas with minimal or no road access. We classified a tiger into one of these three treatments based on which types of roads bisected their 50% minimum convex polygon home ranges. Over a 9-year period (1991-2000), adult female survival was greatest (χ 2 = 12.2, df = 2, p = 0.002) for radiocollared tigers in roadless areas. All adult female tigers in roadless areas survived their tenure in those locations (n = 2), whereas all died or disappeared prematurely from areas with primary roads (n = 6). Cub survival was lower in areas with primary and secondary roads than in roadless areas (χ 2 = 10.9, df = 1, p < 0.009). We evaluated the effects of human disturbance at kill sites by examining 86 kills made by 15 tigers determining whether human disturbance had occurred at the kill site, and examining prey carcasses after tigers left, to estimate the percent meat eaten and whether the tiger abandoned the kill following human disturbance. Tigers undisturbed at kills consumed more meat ( Z = 3.71, p = 0.0002) from each kill than disturbed tigers did. Undisturbed tigers also spent more time at each kill site than disturbed tigers did ( Z = 2.3; p = 0.02). Abandonment of kills occurred in 63% of 24 instances when tigers were disturbed by people. Because roads decrease the survivorship and reproductive success of tigers, we recommend that in habitats managed for tigers, construction of new roads should be prohibited wherever possible and access to secondary roads (e.g., logging roads) should be reduced or prevented wherever possible. Protected areas seem to cease functioning as source populations where road access exists, and unprotected areas-the majority of Amur tiger range-cannot sustain stable populations with the increasing threat of human access to tiger habitat.