Evaluating Physiological Stress in Sumatran Tigers (Panthera Tigris Ssp
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Volume 2 • 2014 10.1093/conphys/cou038 Research article Themed Issue Article: Stress in Vertebrates Evaluating physiological stress in Sumatran tigers (Panthera tigris ssp. sumatrae) managed in Australian zoos Tempe Parnell1, Edward J. Narayan1*, Michael J. L. Magrath2, Sheila Roe2, Giles Clark3, Vere Nicolson4, Patrick Martin-Vegue4, Al Mucci4 and Jean-Marc Hero1 1Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast campus, Queensland 4222, Australia 2Wildlife Conservation and Science, Zoos Victoria, PO Box 74, Parkville, Victoria 3052, Australia 3Australia Zoo, Steve Irwin Way, Beerwah, Queensland 4519, Australia 4Dreamworld, Parkway Coomera, Queensland 4209, Australia *Corresponding author: Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast campus, Queensland 4222, Australia. Tel: +61 0401697287. Email: [email protected] Glucocorticoid quantification using non-invasive methods provides a powerful tool for assessing the health and welfare of wild- life in zoo-based programmes. In this study, we provide baseline data on faecal-based glucocorticoid (cortisol) monitoring of Sumatran tigers (Panthera tigris ssp. sumatrae) managed at the Melbourne Zoo in Victoria, Australia. We sampled five tigers daily for 60 days. Faecal cortisol metabolites (FCMs) in tiger faecal extracts were quantified using enzyme immunoassays that were successfully validated using parallelism and accuracy recovery checks. Two female tigers had significantly higher mean FCM levels than the two males and another female, suggesting that females may have higher FCM levels. A significant elevation was noted in the FCM levels for one female 2 days after she was darted and anaesthetized; however, the FCM levels returned to base- line levels within 3 days after the event. Comparative analysis of FCM levels of tigers sampled at Melbourne Zoo with tigers sampled earlier at two other Australian Zoos (Dreamworld Themepark and Australia Zoo) showed that FCM levels varied between zoos. Differences in the enclosure characteristics, timing of sampling, size and composition of groupings and training procedures could all contribute to this variation. Overall, we recommend the use of non-invasive sampling for the assessment of adrenocorti- cal activity of felids managed in zoos in Australia and internationally in order to improve the welfare of these charismatic big cats. Key words: Australia, faecal cortisol metabolites, stress, tigers, welfare, zoos Editor: Steven Cooke Received 30 June 2014; Revised 27 July 2014; Accepted 30 July 2014 Cite as: Parnell T, Narayan EJ, Magrath MJL, Roe S, Clark G, Nicolson V, Martin-Vegue P, Mucci A, Hero J-M (2014) Evaluating physiological stress in Sumatran tigers (Panthera tigris ssp. sumatrae) managed in Australian zoos. Conserv Physiol 2: doi:10.1093/conphys/cou038. Introduction management strategies (Hutchins et al., 2003; Dehnhard et al., 2008). Understanding the physiology of animals in captivity and Ex situ management of wildlife through zoological programmes how their health can be jeopardized by physiological stress from is of particular importance for endangered species at risk of novel environments and husbandry practices are crucial for extinction in their natural environment and whose existence maintaining sustainable and healthy captive populations (Hing relies on human intervention and support through captive et al., 2014). Conservation physiology is an emerging discipline © The Author 2014. Published by Oxford University Press and the Society for Experimental Biology. 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse distribution and reproduction in any medium, provided the original work is properly cited. Research article Conservation Physiology • Volume 2 2014 of conservation biology (Cooke et al., 2013), which applies non- In this study, we aimed to quantify baseline FCM levels of invasive technologies to provide quantitative assessment of the Sumatran tigers managed at the Melbourne Zoo (Victoria, various effects of environmental stress in wildlife (Wielebnowski Australia). The main objectives were as follows: (i) to quantify et al., 2002a, b; Narayan et al., 2013a, b). Faecal cortisol metab- and compare the range and magnitude of FCM levels between olite (FCM) enzyme immunoassay (EIA) and radioimmunoassay male and female Sumatran tigers; (ii) to examine the physio- are widely used to measure baseline levels of FCMs, and the logical response of individual tigers to specific stressors (dart- magnitude of change (rise or fall) in FCM is a widely accepted ing and anaesthesia); and (iii) to compare the mean FCM levels index of physiological stress (Young et al., 2004). Quantitative of male and female Sumatran tigers at three Australian zoos assessments of physiological stress can also support zoo pro- (Melbourne Zoo, Australia Zoo and Dreamworld Themepark). grammes through improvements to husbandry practices so that the physiological adaptation and wellbeing of animals is enhanced and reproductive success achieved (Young et al., 2004). Materials and methods The wild population of the Sumatran tiger sub-species is Sample collection exclusively found on the Indonesian island of Sumatra. With We measured FCMs in five Sumatran tigers at Melbourne Zoo fewer than 400 individuals remaining in the wild, this sub-spe- (Victoria, Australia) and compared these with FCM levels in cies is of particularly high priority for captive breeding pro- Sumatran tigers from Dreamworld Themepark and Australia grammes due to their critically endangered status (CR; IUCN Zoo. Melbourne Zoo is managing these five Sumatran tigers as Red List; Chundawat et al., 2011). Acquiring new knowledge valuable members of Australia’s national tiger breeding pro- about tiger stress physiology will allow zoos to progress and gramme (Table 1). These tigers are related to each other, because excel in areas of husbandry practices, veterinary care, nutrition, four of the individuals (two male and two female) are siblings exhibit designs and population genetics (Wielebnowski, 2003). from the same litter, born to the fifth individual (mother, Despite its usefulness and practicality, only limited research to female). The study was designed to obtain a profile of FCMs by date has focused on non-invasive methods for evaluating the time (days) for each tiger. Faecal samples were collected daily stress physiology of tigers (Naidenko et al., 2011; Narayan when available for each tiger over 60 days, beginning in et al., 2013a). Terio et al. (2004) highlighted the need for more February 2013. All fresh samples (<12 h old) were collected data on baseline FCM concentrations for felids in captivity. early in the morning from the cage of individual tigers and pre- Pride (2005) also suggested that identification of sub-clinical served immediately by freezing at −20°C in sealed plastic bags. physiological stress using FCM indices can allow managers to focus on high-risk animals that are most vulnerable. We Extraction of FCMs urgently require information on baseline FCM profiles of tigers obtained from as many zoos as possible to develop a compre- Extraction of FCMs followed methods previously described by hensive understanding of how captive tigers respond to differ- Wielebnowski et al. (2002a) for the clouded leopard (Neofelis ent environmental and management interventions. This nebulosa) and used recently in numerous studies by our research information will allow us to compare the stress hormone levels group (Narayan et al., 2012, 2013a, b, 2014; Evans et al., of tigers between zoo facilities, which will significantly improve 2013). Briefly, all faecal samples were dehydrated in a lyophi- our ability to identify, manage, minimize and mitigate threats to lizer, then sieved and pulverized. Homogenized faecal powder tigers in zoos. Narayan et al. (2013a) published the first detailed (0.2 g) was boiled in a 90% ethanol solution for 20 min to study on the stress physiology of tigers in captivity at two achieve maximal binding of the hormone metabolites to the Australian zoos (Dreamworld Themepark and Australia Zoo), aqueous solution. The samples were centrifuged for a 5 min including laboratory and biological validation of faecal cortisol period at 6050 × g, allowing separation of any remaining solids. metabolite analysis for two tiger sub-species, the Bengal From this, the supernatant was recovered and taken to dryness (Parthera tigris tigris) and Sumatran tigers (Parthera tigris in a fume cupboard. Extracted particles adhering to the vessel sumatrae). wall were reconstituted in an assay buffer (39 mm NaH2PO4. Table 1: Descriptive statistics for faecal cortisol metabolite values of tigers (n = 5) at Melbourne Zoo, Victoria, Australia Total sampling Mean FCMs [ng (g dry Tiger Name SEM CV (%) Minimum Maximum period (days) faeces) −1] Male 1 Aceh 14 4.86 2.01 154 0.24 30.58 Male 2 Hutan 13 15.56 7.67 177 1.82 103.71 Female 1 Rani 32 48.43 7.26 154 4.66 179.49 Female 2 Indrah 21 15.31 3.87 115 2.59 67.59 Female 3 Binjai 20 43.60 11.63 119 5.75 215.31 Abbreviations: CV, coefficient of variation; FCMs, faecal cortisol metabolites. 2 Conservation Physiology • Volume 2 2014 Research article H2O, 61 mm NaHPO4, 15 mm NaCl and 0.1% bovine serum sentation of baseline FCM levels and the coefficient of varia- albumin, pH 7.0) in preparation for analysis of FCMs