Peer Reviewed Science May ’17

Welcome to May’s edition of Zoo Science for Keepers and Aquarists! Loads of aquarist peer reviewed information this month.

Aquaculture – May 2017 Volume 474

Liu D., Pedersen L.F, Straus D.L., Kloas W., Meinelt T., (2017) Alternative prophylaxis/disinfection in aquaculture – Adaptable stress induced by peracetic acid at low concentration and its application strategy in RAS, Aquaculture, 474:82-85

Abstract: The application of peracetic acid (PAA) at low concentrations has been proven to be a broad-functioning and eco-friendly prophylaxis/disinfection method against various fish pathogens. However, there is lack of knowledge on how to apply PAA in a recirculating aquaculture system(RAS), and whether the application of PAA at low concentration

can affect fish welfare. In the present study, PAA was applied in a pilot-scale carp (Cyprinus carpio) RAS (comprised of a fish culture tank of 1 m3, a reservoir tank of 600 L and a filter complex of 400 L) every 3 or 4 days for 5 weeks, and the stress response of fish was monitored during every second PAA application by measuring cortisol in water. Results showed that the increase of water cortisol became less pronounced and the decrease

of water cortisol occurred earlier after repeated applications of PAA, which indicates an adaptation of the stress response to PAA in the carp. Moreover, the mathematic model showed that the equal distribution of PAA in RAS was a slow progress, which depended on tanks size and flow rate. To avoid potential harm to the biofilter in RAS during PAA application, it’s suggested that PAA should be applied only to the fish culture tank at a reduced flow rate.

Statement of relevance: Fish welfare becomes more and more important in aquaculture. However, there is a lack of knowledge if routine prophylaxis/disinfectant might affect fish welfare. In the present study, we tested how fish responded to repeated applications of peracetic acid (PAA) in a pilot-scale recirculating aquaculture system (RAS) via measurement of cortisol in water. The results showed that fishes reduced their stress during subsequent

PAA application, indicating adaptation of fish to repeated prophylaxis/disinfection with PAA. Moreover, we established a model and measured the PAA concentration onsite to investigate the distribution of PAA in RAS. We found out that by simply adding PAA only to the fish culture tank with a reduced flow rate can avoid the potential harm on the biofilter.

Watten B.J., Mudrak V.A., Echevarria C., Sibrell P.L., Summerfelt S.T, Boyd C.E., (2017) Performance and application of a fluidized bed limestone reactordesigned for control of alkalinity, hardness and pH at the WarmSprings Regional Fisheries Center, Aqualculture, 474:97-106,

Abstract: Springs serving the Warm Springs Regional Fisheries Center, Warm Springs, Georgia, have pH, alkalinity,and hardness levels that lie under the range required for successful fish propagation while free CO2is well above allowable targets. We evaluate a pre-treatment process that exploits limestone’s (CaCO3) ability to react away hydrogen ions (H+) and carbon dioxide (CO2) while increasing alkalinity (HCO3−) and calcium(Ca2+) concentrations, i.e.CaCO3+ H+↔ HCO3−+ Ca2+CaCO3+ CO2+ H2O ↔ Ca2++ 2HCO3− Limestone sand was tested in both pilot and full scale fluidized bed reactors (CycloBio®). We first established the bed expansion characteristics of three commercial limestone products then evaluated the effect of hydraulic flux and bed height on dissolution rate of a single selected product (Type A16 × 120).Pilot scale testing at 18C showed limestone dissolution rates were relatively insensitive to flux over the range 1.51–3.03 m3/min/m2but were sensitive (P < 0.001; R2= 0.881) to changes in bed height (BH,cm) over the range 83–165 cm following the relation: (Alkalinity, mg/L) = 123.51 − (3788.76 (BH)). Differences between filtered and non-filtered alkalinity were small (P > 0.05) demonstrating that limestone was present in the reactor effluent primarily in the form of dissolved Ca(HCO3)2.Effluent alkalinity exceeded our target level of 50 mg/L under most operating conditions evaluated with typical pilot scale values falling within the range of 90–100 mg/L despite influent concentrations of about 4 mg/L. Concurrently,CO2 fell from an average of 50.6 mg/L to 8.3 mg/L (90%), providing for an increase in pH from 5.27 to a mean of 7.71. The ability of the test reactor to provide changes in water chemistry variables that exceeded required changes allowed for a dilution ratio of 0.6. Here, alkalinity still exceeded 50 mg/L, the CO2con-centration remained well below our limit of 20 mg/L (15.4 mg/L) and the pH was near neutral (7.17).Applying the dilution ratio of 0.6 in a full scale treatment plant at the site reduced by 40% the volume of spring water that is directed through each of three parallel reactors that combined react away 49,000 kg of limestone/yr.

Aquacultural Engineering- April 2017 Volume 77

Sebök S., Herppich W.B., Hanelt D., (2017)  Development of an innovative ring-shaped cultivation system for aland-based cultivation of marine macroalgae, Aqua. Eng. 77:33-41,

DOI 10.1007/s10499-016-0047-4

Abstract: Marine macroalgae become increasingly important as a regenerative source of biomass for the production of food, pharmaceuticals, cosmetics and energy. An increasing and environmentally sound utilization of algae requires a closed, land-based cultivation, not limited to coastal or offshore areas. Within this study, segmental and ring-shaped cultivation vessels were developed and compared to tumble cultivation in a circular tank. The development of these innovative approaches also considered economic efficiency, adaptability, handling and reliability. The growth rates achieved by cultivating the red algae P. palmata and C. crispus and the green alga U. lactuca over a test period of 7 d were used to evaluate these experimental models. Mean growth rates of P. palmata and C. crispus in the ring-shaped cultivation model were slightly decreased whereas growth rate of U. lactuca was similar or increased compared to tank cultivated algae. The developed ring-shaped cultivation system distinctly lowered variable costs by reducing the necessary volume of cultivation medium. An increased control of the cultivation process was achieved by separating the supply of CO2 and nutrients, and the temperature control from agitation.

Aquaculture International- April 2017 Issue 25

Hagemann A., Vorren S.H., Attramadal Y.,  Evjemo J.O., Olsen Y., (2017) Effects of different wavelengths and intensities of visible light on the hatching success of Acartia tonsa Dana eggs, Aquaculture Int. 25: 531-541,

DOI 10.1007/s10499-016-0047-4

Abstract: Mass production of copepod eggs in intensive systems has recently been demonstrated to be economically feasible; a few companies producing copepod eggs have been established. It is well documented that water physiochemical variables could significantly influence the hatching success of Acartia tonsa Dana, 1849 (Copepoda: Calanoida) eggs. This information is important to end users in order to achieve a predictable output of nauplii when hatching eggs for live feed production in marine larviculture. The effect of different wavelengths and intensities of light on the 48-h egg hatching success (HS) of fresh and cold-stored (2 °C) A. tonsa eggs were examined in the present study. No correlations were observed between HS and light environment for fresh or cold eggs when they were hatched at wavelengths between 400 and 630 nm and at light intensities of 0.0016, 1, 5 and 16 µE m−2 s−1. Fresh eggs displayed the highest HS and declined with the time of storage. However, eggs being of same age showed a similar HS regardless of the light intensity and wavelength, including when hatched in darkness. We suggest that A. tonsa eggs produced in intensive cultures can be hatched without any concern to the light environment.

Aquaculture Research- April 2017 Issue 48

Cupp A. R., Fredricks K. T., Porcher S. T., Smerud J. R., Hartleb C. F.,Gaikowski M. P. (2017), Survival and behavioural responses of cool and warm water fish sedated with AQUI-S®20E (10% eugenol) at high loading densities. Aquac Res, 48: 1576–1589.


Abstract: This study evaluated the effects of AQUI-S®20E (10% eugenol) sedation on the survival and behaviour of yellow perch Perca flavescens (Mitchill) and Nile tilapia Oreochromis niloticus L. held in high loading densities. Fish were held in 0–300 mg L−1 AQUI-S®20E (0–30 mg L−1 eugenol) for up to 10 h in static tanks. At 17°C, yellow perch held in 200 and 300 mg L−1 AQUI-S®20E were lightly sedated for up to 7 h. Yellow perch at 200 and 300 mg L−1 AQUI-S®20E also had >95% mean survival 7-days post exposure using loading densities up to 360 g L−1. Nile tilapia were only sedated for ≤3 h in concentrations up to 300 mg L−1 at 22°C and had >90% mean survival at loading densities ≤480 g L−1. Ammonia in tanks increased significantly as loading density increased, but treatment with AQUI–S®20E did not reduce ammonia accumulation. Results suggest that AQUI–S®20E was effective to sedate yellow perch and Nile tilapia at high loading densities, but sedation varied with loading density and species.

Jagadis I., Kavitha M., Padmanathan J., Maharshi A., Varadarajakumar A. (2017), Lessons on broodstock maintenance, spawning, larval rearing and juvenile production of marine gastropods of ornamental value. Aquac Res, 48: 2581–2592.


Abstract: Research on marine gastropod breeding in India is in its infancy and scanty literature is only available. To fill the lacunae, marine gastropods of three ornamentally valued and conservation important groups such as Cyprids, Strombids and Muricids were held under captivity and studied for their broodstock maintenance, spawning behaviour, larval rearing and metamorphosis into juveniles at the Shellfish Hatchery of Central Marine Fisheries Research Institute, Tuticorin. Valuable information on the focal themes of the article was obtained for Strombids and Muricids leading to the successful life cycle closing for Lambis lambis and Chicoreus virgineus are reported earlier. In the present study, experiments were conducted on aspects such as post-metamorphosed juvenile rearing up to 76 days post hatch for L. lambis, spawning, larval development and life cycle closing and reasonable level of juvenile production (8.8%) for Chicoreus ramosus. In addition, the primary observations on the captive breeding of Cypraea tigris with reference to its egg mass, brooding habit and early development is reported. However, while studying these groups few unanswered questions and bottle necks in their breeding nature, larval rearing and metamorphosis arose. The following account details the experiments conducted and results obtained in each of the focal themes of the paper and the constraints faced.

Aquaculture Nutrition- April 2017 Issue 23

Karga J., Mandal S.C. (2017), Effect of different feeds on the growth, survival and reproductive performance of zebrafish, Danio rerio (Hamilton, 1822). Aquacult Nutr, 23: 406–413.


Abstract: Present experiment was conducted to determine the effect of different feeds with varying protein levels on the growth, survival and reproductive performance of zebrafish, Danio rerio. The control diet (T1) was wild-collected zooplankton from local fish ponds, while test diets with 350 g kg−1protein (T2), 400 g kg−1 protein (T3) and 450 g kg−1 protein (T4) were formulated and fed to fish for a period of 210 days. The significantly (P < 0.05) highest mean weight gain and specific growth rate were observed in T1, which were similar with T3 and T4. The significantly (P < 0.05) highest number of egg production per female and relative fecundity were found in T1, followed by T4 and T3 while T2 produced lowest number of eggs. No significant (P > 0.05) differences were observed in brood survival rate, fertilization and hatching rate among the dietary treatments. The highest (P < 0.05) fry survival rate was recorded in T1, followed by T3 and T4. Thus, it is suggested that control diet i.e. mixed zooplankton exhibited better growth, reproductive performance and fry survival rate. However, diet containing 400 g kg−1 crude protein also gave comparable results in terms of growth, survival and reproductive performance of zebrafish.


Palma J., Andrade J.P., Bureau D.P. (2017), The impact of dietary supplementation with astaxanthin on egg quality and growth of long snout seahorse (Hippocampus guttulatus) juveniles. Aquacult Nutr, 23: 304–312.


Abstract: This study investigated the effect of dietary astaxanthin supplementation on egg quality and juvenile growth of long snout seahorse (Hippocampus guttulatus). Captive breed seahorse broodstock were fed four diets composed of frozen shrimp [Atlantic ditch shrimp, Palaemonetes varians) used as a vector to deliver artificial diets with increasing levels of astaxanthin (0, 75, 100 and 125 mg kg−1 dry weight)]. The results indicated that the astaxanthin uptake into eggs from the enriched shrimp diets was highly efficient. Females fed unsupplemented astaxanthin diet produced similar-sized eggs with lower concentration of astaxanthin than females fed diets with astaxanthin. The lower concentration of astaxanthin in the eggs was correlated with the production of smaller juveniles in comparison with the juveniles hatched from parents fed supplemented astaxanthin diets. Juvenile growth and survival was limited by their size on release from the male’s pouch as at the end of 28-day postparturition juveniles produced with the diet with no astaxanthin were still significantly smaller (P < 0.05) than those produced from parents fed astaxanthin-supplemented diets. These results demonstrate a significant benefit of dietary astaxanthin supplementation in long snout seahorse diets in terms of improved egg quality and juvenile growth and survival.


Walsh, Brendan. Asian elephant (Elephas maximus) sleep study – long-term quantitative research at Dublin Zoo. Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 82-85, apr. 2017. ISSN 2214-7594.

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Abstract: Sleep is an essential aspect of Asian elephant (Elephas maximus) wellbeing in zoos. Recent improvements in elephant habitats and husbandry, including sand substrates, feeding enrichments and related herds, have increased their wellbeing, but few studies have focused on night time behaviour. This study measured sleep behaviour in a group of Asian elephants in Dublin Zoo and how it related to elephant husbandry. A total of 704 nights of elephant behaviour were recorded over a 33-month period. Closed circuit television cameras, with infrared abilities, were used to record behaviour from 1900-0800 nightly. Eight elephants were studied: three related adult cows, both while they were pregnant and not pregnant, one sub-adult cow, one adult bull, two bull calves and one cow calf. Adults slept for an average of 3 hr 33 min per night, while calves slept an average of five hours eight mins per night. There was a clear relationship between age and sleep: older individuals slept less. One of the three elephants who became a mother during the study slept 68.3% less in the first nine months after giving birth. Another mother slept 13% less after parturition, while a third female slept more after giving birth (up 10.3%). Reduction in sleep duration appeared to be primarily because of calf guarding behaviour, but establishing successful suckling may also be a factor. On rare occasions, the adult cows were given the option of sand and concrete surfaces. The adult bull was given this option nightly. Both sexes always chose sand to sleep on. The bull showed consistent sleep duration, while sleep in the other elephants varied through pregnancy, parturition and the immediate post-partum period. Elephants live in related, matriarchal herds in the wild, where they traverse substrates of sand and soil. Results of this study suggest that zoos should aim to mimic these features to permit appropriate levels of sleep and improve wellness.

Schäfer, Florian; Reiners, Tobias Erik. Long term vs. short term impact of founder relatedness on gene diversity and inbreeding within the European Endangered Species Programme (EEP) of the red panda (Ailurus f. fulgens). Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 86-91, apr. 2017. ISSN 2214-7594.

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Abstract: Traditionally, studbooks have been used as the major tool for the scientific management of ex-situ populations organised in breeding programmes. Well documented pedigree information enables managers to sufficiently monitor population size, demographic stability and the level of genetic diversity. However, breeding programes can only maintain the genetic information which is brought into captivity by wild caught founder animals. In most studbooks little is known about those individuals. This is also true for the red panda (Ailurus fulgens), a charismatic but threatened flagship species. Conservation breeding of this remarkable mammal species started in the early 1960s and is nowadays coordinated through a Global Species Management Plan (GSMP). In Europe the Endangered Species Programme (EEP) forms the biggest regional breeding group of red pandas (subspecies A. f. fulgens). Little is known about the true origin of the 23 founders of the EEP and how their unknown relationships may affect their living descendants now and in the future. Studbook data on 1350 individuals were analysed for different assumptions about founder relationships and compared with each other. We provide studbook-based evidence that the annual change in genetic parameters (gene diversity and mean inbreeding) are not affected in long-term by the original founder relationship within strongly intermixed zoo populations managed for mean kinship. Our results point out the importance of good genetic management in the early years of breeding programmes. These early years are crucial in implementing knowledge of founder relationships in the studbook, since a population becomes genetically equalised within the first decades and new information obtained later has no significant effects on subsequent genetic trends.

Leuchner, Lisa et al. Chitin supplementation in the diets of captive giant anteaters (Myrmycophaga tridactyla) for improved gastrointestinal function. Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 92-96, apr. 2017. ISSN 2214-7594.

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Abstract: Clinical issues associated with keeping giant anteaters (Myrmecophaga tridactyla) in captivity may be linked with colon health and digestive function. Chronic loose stools are one such problem often suspected to be related to dietary intake. The objective of this study was to determine the acceptability, digestibility and faecal composition in a population of captive giant anteaters on four different experimental diets, including a baseline diet (B) comprising high fibre primate biscuit and dry feline diet, ground and mixed together then blended with water, or a commercial dry insectivore diet (INS), also ground and mixed with water. Other treatments included addition of 5 or 10% of dry matter (DM) as ground chitin added to B. No difference in faecal DM or faecal organic matter content was observed across all experimental diets; faecal ash was increased on B5 compared to B10 or INS treatments, indicating a possible impact on mineral nutrition. Similarly, no differences were observed in DM digestibility, or neutral detergent fibre (NDF) or acid detergent fibre (ADF) fermentation across all diets. The majority of the dietary components of the four different diets are highly digestible and/or fermentable (> 90% for all except fibre fractions). Crude fat and ADIN digestibility, and calcium and magnesium absorption were significantly higher in the diet that was formulated containing 5% chitin. Apparent digestion of NDF (82-91%) or ADF (74-88%), as measures of chitin, did not differ statistically among the diets in this study; ranges of disappearance of these components are high compared to other mammals, but within the ranges reported for other species.

Ito, Masaaki et al. Food preparation behaviour of babirusa (Babyrousa celebensis). Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 97-103, apr. 2017. ISSN 2214-7594.

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Abstract: Food preparation behaviour of sand-contaminated food articles by two zoo-based Sulawesi babirusa (Babyrousa celebensis) was observed and recorded as video imaging data at Bali Zoo, Indonesia during an observation period of six days in July 2012. In earlier preliminary studies of four animals, comprising two mother-infant pairs, three animals held pieces of cut sweet potatoes in the mouth, carried them to a neighbouring water trough, dropped or dipped them in the water, and then began eating. This behaviour was repeated at almost every feeding time. To characterise and elucidate this food preparation behaviour further, and within the management constraints of a zoo environment, experiments with various test feeds were designed; the dipping of food articles into water was video-recorded on 37 occasions. This behaviour by the babirusa was related to (1) deliberate sand-contamination of the surface of the food; (2) deliberate provision of large-sized pieces of food, and (3) the supply of large amounts of food at one time. The distance of the water source from the food seemed to play a role in the expression of the ‘food washing’ behaviour, with short (1.5 m) distances preferred over longer (6 m) distances. The frequency of this type of babirusa food preparation behaviour was higher during the second half of a feeding period.

Le François, Nathalie Rose. Implementation of sulphur denitrification in a large-scale fully recirculated cold-SW aquarium: A sustainability practice. Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 104-108, apr. 2017. ISSN 2214-7594.

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Abstract: Autotrophic sulphur-based denitrification (ASD) was evaluated to control nitrate accumulation in the marine aquatic exhibit of the Biodôme de Montréal (Montréal, QC, Canada). Different substrates (two sulphur and two calcareous sources were tested), flow-rates and configurations (homogenous and low to high stratification levels) were evaluated that successively improved nitrate removal rates (g N-NO3- · day-1) and/or start-up time. Despite pronounced suboptimal conditions for anaerobic denitrifying bacteria, Thiobacillus denitrificans i.e. saline (24 PSU), cold (5-10oC) and aerated waters, our R&D efforts lead to the development of an efficient, simple, custom-made ASD unit adapted to a priori unfavourable conditions. The Rocky Shore exhibit (25 m3) housing the most sensitive marine aquatic species of our live collections (mostly invertebrates) previously operated at ≥ 50 mg N-NO3- · L-1 is now at ~ 20 mg N-NO3- · L-1. Considering the significant economic and environmental gains achieved (e.g. sustainability) following the implementation of this technology at a small-scale on the Rocky Shore exhibit (100 kg of sulphur), a 10-fold upscaling (1000 kg of sulphur) ASD unit to be connected to the La Baie exhibit (2500 m3) is planned.

Bioscience Journal

de Carvalho, Thatijanne Santos Gonzaga, Márcio Gilberto Zangeronimo, Carlos Eduardo do Prado Saad, Vanessa Daniela Lázara de Assis, and Virgínia Mara Pereira Ribeiro. “The behavioural study of the bush dog (Speothos venaticus) in captivity with environmental enrichment” Bioscience Journal 33, no. 2 (2017).

Abstract: The bush dog (Speothos venaticus) is very rare animal species, whose maintenance and breeding in captivity can induce the expression of atypical behaviour. Information concerning environmental enrichment and assessment models of the behaviour of this species in the literature are insufficient. Therefore, a study was conducted in the Zoo-Botanic Foundation of Belo Horizonte, Minas Gerais, Brazil, to evaluate the behaviour of two male bush dogs kept in captivity with different types of environmental enrichment, in April-May 2012. Data collection was performed before, during and after the presence of the environmental enrichment, three times a week in the morning and afternoon on alternate days for ten minutes, with immediate recording of activity performed by the animal every minute. It was observed that the animals interacted with all three types of ENRI used, but showed a greater interest in ENRI-2. No stereotyped behaviour or aggressive behaviour was observed, suggesting satisfactory welfare conditions for the animals in all environments tested. We conclude that the enrichment protocols can be used to stimulate the natural behaviour of the species, aiding the well-being and quality of life in captivity.

Behavior Research Methods

Oh, J. and Fitch, W.T., 2016. CATOS (Computer Aided Training/Observing System): Automating animal observation and training. Behavior research methods 49(1), pp.13-23.

Abstract: In animal behavioral biology, an automated observing/training system may be useful for several reasons: (a) continuous observation of animals for documentation of specific, irregular events, (b) long-term intensive training of animals in preparation for behavioral experiments, (c) elimination of potential cues and biases induced by humans during training and testing. Here, we describe an open-source-based system named CATOS (Computer Aided Training/Observing System) developed for such situations. There are several notable features in this system. CATOS is flexible and low cost because it is based on free open-source software libraries, common hardware parts, and open-system electronics based on Arduino. Automated video condensation is applied, leading to significantly reduced video data storage compared to the total active hours of the system. A data-viewing utility program helps a user browse recorded data quickly and more efficiently. With these features, CATOS has the potential to be applied to many different animal species in various environments such as laboratories, zoos, or even private homes. Also, an animal’s free access to the device without constraint, and a gamified learning process, enhance the animal’s welfare and enriches their environment. As a proof of concept, the system was built and tested with two different species. Initially, the system was tested for approximately 10 months with a domesticated cat. The cat was successfully and fully automatically trained to discriminate three different spoken words. Then, in order to test the system’s adaptability to other species and hardware components, we used it to train a laboratory rat for 3 weeks.


Vaz, J., Narayan, E.J., Kumar, R.D., Thenmozhi, K., Thiyagesan, K. and Baskaran, N., 2017. Prevalence and determinants of stereotypic behaviours and physiological stress among tigers and leopards in Indian zoos. PloS one, 12(4), p.e0174711.

Abstract: India’s charismatic wildlife species are facing immense pressure from anthropogenic-induced environmental perturbations. Zoos play a major role in the conservation of threatened species, but their adaptation in captivity is posing a major challenge globally. Stress from inadequate adaptation could lead to suppression of cognitive functioning and increased display of stereotypic behaviour. It is thus necessary to measure biological traits like behaviour, stress physiology, and contextual factors driving the animals maintained at zoos. In this study, we assessed stereotypic behaviour and stress physiology employing standard behaviour scoring, non-invasive stress monitoring, and their contextual drivers in a sub-population of two large felid species managed in six Indian zoos. The prevalence and intensity of stereotypic behaviours and levels of faecal corticosterone metabolites (FCM) were ascertained among 41 Royal Bengal tigers Panthera tigris tigris and 21 Indian leopards Panthera pardus fusca between April 2014 and March 2015. Behavioural observations showed that tigers spent more time stereotyping (12%) than leopards (7%) during daylight hours. Stress levels assessed using FCM revealed that tigers (23.6 ± 1.62 ng/g) had marginally lower level of corticosterone metabolites than leopards (27.2 ±1.36 ng/g). Stereotypic behaviour increased significantly with FCM level when the effect of health status was controlled in tigers, and the effects tree cover, stone, den and keeper attitude controlled in leopards. Comparison of stereotypes of tigers with various biological and environmental factors using binary logistic regression revealed that stereotypic prevalence decreased with increased enclosure size, and enclosure enrichments like presence of pools and stones, when managed socially with conspecifics, and with positive keeper attitude, these factors accounting for 43% of variations in stereotypic prevalence among tigers. Stereotype among leopards was significantly absent when associated with increased tree cover and presence of pool, and den in the enclosure, age and among zoo-born than wild-born ones. These factors explain 81% of variations in stereotypic prevalence in them. A comparison of FCM levels with context-dependent factors revealed that stress levels among tigers decreased significantly with enclosure size and with individuals from nil to low, and severity of health issues. These factors explain 64% of variations in FCM levels. In leopards, the presence of stones in the enclosure and keepers with positive attitude resulted in significant decrease in FCM levels, these factors together accounting for 94% of variations. Multiple regressions on selected variables based on Factor Analysis of Mixed Data showed that in tigers the intensity of stereotype decreased significantly with enclosure size, sociality and positive keeper attitude and FCM level with health problems. Similarly, analyses in leopards revealed that intensity of stereotype decreased significantly with tree cover, age and FCM level with positive keeper attitude. Overall, our study suggests that to reduce stereotypes and stress level, tigers in captivity should be managed in larger enclosures enriched with pool, and stones, and in appropriate social conditions with adequate veterinary care. Leopards should be managed in enclosures with dense tree cover, pool, stones and den. Positive keeper attitude plays a crucial role in the welfare of both the species in captivity. Our study is promising and is comparable with their natural behaviour in the wild; for example, tigers require larger natural habitats, while leopards can manage even with smaller isolated patches but with dense vegetation cover.

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