Glucocorticoid Stress Responses of Reintroduced Tigers in Relation to Anthropogenic Disturbance in Sariska Tiger Reserve in India

RESEARCH ARTICLE Glucocorticoid Stress Responses of Reintroduced Tigers in Relation to Anthropogenic Disturbance in Sariska Tiger Reserve in India Subhadeep Bhattacharjee1, Vinod Kumar2, Mithileshwari Chandrasekhar2, Manjari Malviya1, Andre Ganswindt3, Krishnamurthy Ramesh1, Kalyanasundaram Sankar1, Govindhaswamy Umapathy2* 1 Wildlife Institute of India, Chandrabani, Dehradun, Uttarakhand, India, 2 Laboratory for the Conservation of Endangered Species (LaCONES), CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India, 3 Endocrine Research Laboratory, Department of Anatomy and Physiology, University of Pretoria, Onderstepoort, 0110, South Africa * OPEN ACCESS Citation: Bhattacharjee S, Kumar V, Chandrasekhar M, Malviya M, Ganswindt A, Ramesh K, et al. (2015) Glucocorticoid Stress Responses of Reintroduced Tigers in Relation to Anthropogenic Disturbance in Sariska Tiger Reserve in India. PLoS ONE 10(6): e0127626. doi:10.1371/journal.pone.0127626 Academic Editor: Balasubramanian Senthilkumaran, University of Hyderabad, INDIA Received: December 30, 2014 Accepted: April 17, 2015 Published: June 10, 2015 Copyright: © 2015 Bhattacharjee et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Tiger (Panthera tigris), an endangered species, is under severe threat from poaching, habitat loss, prey depletion and habitat disturbance. Such factors have been reported causing local extermination of tiger populations including in one of the most important reserves in India, namely Sariska Tiger Reserve (STR) in northwestern India. Consequently, tigers were reintroduced in STR between 2008 and 2010, but inadequate breeding success was observed over the years, thus invoking an investigation to ascertain physiological correlates. In the present study, we report glucocorticoid stress responses of the reintroduced tigers in relation to anthropogenic disturbance in the STR from 2011 to 2013. We found anthropogenic disturbance such as encounter rates of livestock and humans, distance to roads and efforts to kill domestic livestock associated with an elevation in fecal glucocorticoid metabolite (fGCM) concentrations in the monitored tigers. In this regard, female tigers seem more sensitive to such disturbance than males. It was possible to discern that tiger’s fGCM levels were significantly positively related to the time spent in disturbed areas. Resulting management recommendations include relocation of villages from core areas and restriction of all anthropogenic activities in the entire STR. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: National Tiger Conservation Authority of India (NTCA) and Central Zoo Authority of India, Ministry of Environment and Forests, Government of India and Council of Scientific and Industrial Research (CSIR), Ministry of Science and Technology are acknowledged for providing financial support for the research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Introduction Reintroduction of any species to its former geographic range, where it was locally exterminated, is the last resort for conservation biologists and wildlife managers interested in species recovery programs. Of the various species, reintroduction of carnivores is considered to be a more effective step towards conservation and restoring integrity of natural ecosystems [1] because large carnivores maintain ecological balance as apex predators in e.g. forest areas [2]. However, PLOS ONE | DOI:10.1371/journal.pone.0127626 June 10, 2015 1 / 13 Stress Response in Tigers Competing Interests: The authors have declared that no competing interests exist. reintroduction of carnivores in its original habitat is more challenging both biologically and politically [3], especially large carnivores require extensive habitat which often result in human-animal conflicts [3,4]. In the past, many carnivores have been reintroduced such as the Eurasian lynx (Lynx lynx) to the Alp mountain range in Europe [5], the Canadian lynx (Lynx canadensis) to Colorado in the US [6], the gray wolf (Canis lupus) to the Yellowstone National Park in the US [7], or the black-footed ferret (Mustela nigripes) to the central prairies of the United States [8]. The success of a reintroduction program depends on a variety of key factors including the biology of the species, number of founders, environmental variation, genetic variability, intra-specific competition and reproductive success [9,10]. So far, most of the reintroduction programs failed due to poorly conceptualized planning and subsequent monitoring, resulting in viable populations in only 11% of the cases [11,12]. It therefore becomes highly imperative that reintroduction programs should be based on sound scientific principles and methodology to increase their probability of success. In contrast, the successful reintroduction of the African lion (Panthera leo) and African wild dog (Lycaon pictus) in East Africa during 1996 and 2001 are just two of the few examples that enriched our knowledge regarding the science and management involved during carnivore reintroduction processes [13]. The tiger (Panthera tigris) is an endangered species, restricted to less than 0.6% of its historical range and the remaining estimated global populations of 3000–3500 individuals are under severe threat due to poaching, habitat loss and prey depletion [14–16]. India is one of the important countries for tiger conservation, as it supports ca. 50% of the global wild tiger populations [17]. It is therefore one of the key players for global tiger recovery [18]. Although intense tiger conservation efforts have been made through “Project Tiger” in India since 1972, their population continue to be threatened due to poaching, habitat loss and prey depletion in many parts of India, even resulting in local extinction in protected areas namely Sariska in Western India and Panna in central India in the recent past. As part of the species recovery and conservation management program, tigers were reintroduced into Sariska and Panna Tiger Reserves during 2008–2010 and 2009–2013 respectively [19]. Reintroduced tigers in Panna Tiger Reserve (n = 6; 4 females, 2 males) have been successful in breeding and have given births regularly [20]. In contrast, the reintroduced tigers in Sariska (n = 5; 3 females, 2 males) did not show breeding success until recently, June 2012 [21]. The role of stress in population decline is not clearly understood and might be multifaceted. Glucocorticoids (cortisol and corticosterone) are released under stressful conditions to help the organism defend itself against a perceived stressor [22]. Although the short term release of (...truncated)