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Zoo animal welfare: Modern concerns

Dr Naveen Pandey, MVetSc (Conservation Medicine)

What behavioral changes - sexual aggression or sexual incompatibility - can we think of when a mate is present in an adjoining enclosure around the year? Will such a scenario compromise the tiger’s welfare and wellbeing? (Pic: Naveen Pandey)

At the beginning of April this year, I happened to wait for a taxi outside the historical Zoological Garden at Alipore in Kolkata. The easing period between the two waves of the pandemic had ebbed. Despite the country’s covid figures clocking over a quarter of a million daily, Kolkata’s traffic showed no restraint. The City of Joy's urban discord had attained unbearable proportions amid an electoral cacophony. The noise was painful even for a man. The vet in me connected with over a hundred species residing in the zoo just behind the towering walls and wondered how the animals responded to the ever-increasing noise. The acoustic environment of zoo residents has seen tremendous changes since the zoo started functioning in 1875.

The anthropogenic noise can arise from basic routine activities like fans, air-conditioning, pressure washings, radios, door operation. However, even such noise, often perceived by us to be normal, can cause the sound pressure levels to be changed. The alteration in sound pressure levels triggers stress responses in animals. Sadly, there is no methodical system for continuous welfare assessment of zoo animals across species or even at individual levels in a true holistic welfare monitoring sense. In addition, the urban traffic noise beyond the zoo premise and ongoing construction and expansion of facilities inside the zoo compound are potential stressors.

Anthropogenic sound is just one of the many stressors. Many less-emphasized factors compromise the welfare of zoo animals. I assume that all zoos aim to ensure zoo animals’ welfare. But knowledge gaps are obstructing the delivery of the best welfare requirements.

A lot of our knowledge and understanding of animal welfare stems from studies and observations of farm and domestic animals. The Five Freedoms, first as Brambell Report (1965) and later codified by the Farm Animal Welfare Council (1979), have shaped our vision of animal welfare for decades. Observations and interpretations of an animal’s behavior and health status have formed the core of animal welfare practice. Identification, validation, and monitoring of indices capturing poor welfare measured through behavior and health have been the foundation of welfare assessment for a long time.

A simplistic view that guides us is that the absence of indicators of poor welfare reflects good welfare. We have also assumed that the knowledge of welfare in one species could be applied to other species. (Pic: Naveen Pandey)

We expect the zoo animals to live their lives fully, in contrast to farm animals, where production and metabolic stress coupled with the economy of farming dictate management decisions. The very purposes of the existence of zoo animals and farm animals are different. In modern times, conservation is seen as one of the driving forces for the justification of zoos’ ideal for replacing the entertainment-dominated domain of zoo’s objective. Efforts to maintain behavioral and genetic integrity in zoo animals for conservation purposes may add unknown stressors that we need to study. The mismatch between the natural environment and the captive environment itself is stressful.

Many exotic species may not exhibit obvious symptoms of poor welfare. Survival instinct may encourage an exotic species to hide signs of distress. Acute pain in reptiles may betray even the keen eyes to notice flinching and muscle contractions. For a while, let us visualize a male tiger confined in an enclosure in the proximity of its mate round the year. We know that a male tiger is often a solitary animal, roams a large area, and encounters sexually mature counterparts during estrous only. What behavioral changes - sexual aggression or sexual incompatibility - can we think of? Will such a scenario compromise the tiger’s welfare and wellbeing? How do we measure them?

I find the ‘Keeper Checklists’ in use by David Orban and his colleagues at Disney’s Animal Kingdom a critical starting point for capturing information. It is a tool for customized evaluations of animal’s health, behavior, personality, and wellbeing generated by the animal care and science staff. A precisely defined mix of indicators for physical, behavioral, and husbandry categories are scored daily by experienced animal keepers. A fortnightly analysis of the data collected through the Keeper Checklist helps in the discussion of animal welfare in real-time and appropriate changes could be made. The detailed report of Orban and his colleagues recommends assessing the sensory environment round the clock and suitable mitigation measures to control anthropogenic noise. I wonder if the Zoological Garden at Alipore, too, would benefit from these measures. It can help the vets there to ensure better holistic health for the inmates. Care of geriatric specimens for disorders like neoplasia, arthritis, diabetes, dentistry, and heart failure is an emerging concern as we broaden our understanding of animal welfare.

It is relevant to mention Vicky Melfi’s efforts to highlight a large taxa bias that plagues the study of zoo animals and consequently shapes our knowledge. An analysis of 774 research projects in the British and Irish Association of zoos and Aquariums (BIAZA) indicated 690 projects aimed at mammals which rounds up to 90% of efforts. Even within these mammal-centric studies, around 70% of the research were aimed to study primates only. Similar taxa bias has been observed in research emphasis in Association of Zoos and Aquariums (AZA) member zoos. As a vet, I would largely depend on the scientific knowledge derived through such research projects to deliver the best welfare practices.

The bias towards large mammals obstructs the evolution of evidence-based management for many species. My particular example of a tiger in the preceding paragraph could reflect the large taxa bias! (Pic: Naveen Pandey)

We know that asymptomatic parasitic infections can adversely affect animal’s wellbeing. Due to their large range and habitat, the wild animals are often less exposed to parasitic loads and hence have been genetically less resistant to parasitic infections. When the wild animals are kept in confinement, their vulnerability to parasitic infections increases due to housing and feeding restrictions. Injudicious use of anthelminthic drugs can lead to the appearance of resistant strains. How do we balance the two sides, then? A study at Zoo Negara, Malaysia, found that 89, 54, and 45 % of felines, primates, and hoofed mammals were infested with intestinal parasites ‘even with high husbandry standards’ (Lim, 2008). The study strongly recommended maintaining high standards of husbandry and examination levels to keep the infections in control. As a vet, I would be worried because many of the intestinal parasites found in zoo animals could be of zoonotic importance.

Highly pathogenic avian influenza, West Nile virus, Elephant endotheliotropic herpes virus, mammalian tuberculosis, and avian mycobacteriosis would seek unprecedented attention in the post-covid era (Pic: Naveen Pandey)

Assessment tools like EthoTrak® (developed by the Chicago Zoological Society), and EthoSearch (developed by Lincoln Park Zoo and partners) can be adopted to establish zoo-specific assessment tools and programs. Incorporating modern concepts like Anticipatory Behaviour (Watters, 2014), Cognitive Enrichment (Clark, 2011), and Social Network Analysis (Croft, 2008) in the modern-day management of zoos can help vets to provide optimum health by eliminating the stressors originating from compromised social support. In addition, urban cacophony and rapidly evolving conservation priorities call for increased use of technology for ensuring holistic welfare to zoo animals.

PS: The locations of the images have deliberately been not mentioned by the author. There are no images in this article from Zoological Garden at Kolkata.

(Dr Naveen Pandey holds an advanced veterinary degree in Conservation Medicine from the University of Edinburgh and serves The Corbett Foundation as its Deputy Director and Veterinary Advisor in Kaziranga, northeast India. He can be reached at


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