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Environmental Enrichment

Scientific Papers

White Bear

© Rory Harper

Impact of diet and environmental enrichment management in stereotyped behaviours: a case study in tayra Eira barbara (Beltrán Urrego & Bernal Aguilar, 2024)

January 2024

A case study published in the Journal of Zoo & Aquarium Research evaluated the effects of a change in diet and an enrichment management plan on the behaviour and welfare of a zoo-housed tayra:

✔ Animal provided with a hiding place and 6-day a week sensory, physical, feeding and/or cognitive enrichment.

✔ Stereotypies decreased from 28.8% to 16.2%.

✔ Inactivity decreased from 28.8% to 15.2%.

✔ Increase in locomotion and feeding-related behaviours.

✔ Potential applications to ex situ management of mustelids.

Enhancing welfare in a mixed exhibit: The impact of dispersed whole food on activity levels and feeding behaviours of Mexican military macaws and red-billed curassows (Quintanilla et al., 2023)

October 2023

The behavioural responses of nine Mexican military macaws and two red-billed curassows (mixed-species exhibit) to dispersed whole food was investigated in a study in the Journal of Zoo Aquarium Research:
✔ Macaws: Increased activity (foraging, walking, feeding) and bill manipulation, decreased resting.
✔ Curassows: Increased walking, decreased bill manipulation.
✔ Birds ate the same amount of food in both conditions (chopped vs whole).
✔ Zookeepers spent less time in food preparation when it was presented whole to the birds.

Predatory Responses and Feeding Behaviour of Three Elasmobranch Species in an Aquarium Setting (Costa et al., 2023)

December 2023

The feeding and predatory behaviour of three aquarium-housed elasmobranch species (blacktip reef shark, whitetip reef shark, pelagic stingray) were investigated in a study published in JZBG::
✔ Four feeding methods tested (pole, short buoy, long buoy, and PVC) using five prey species.
 All elasmobranch species interacted with all feeding methods, but the stingrays favoured the pole method.
The whitetip and blacktip reef sharks favoured bony fish and cephalopod prey, respectively.
✔ Applications to the ex situ management and welfare of elasmobranches.

Assessing the impact of environmental enrichment on behavior in understudied armadillo species: A case study (Kelly & Rose, 2023)

November 2023

A study published in Zoo Biology investigated the effects of enrichment (plastic ball, cardboard tube, cardboard box, scatter-feed) on the behaviour of three zoo-housed armadillo species:
Activity remained low throughout the study and was affected by temperature.
Enrichment encouraged alert and exploratory behaviours.
Plastic ball was the most effective enrichment.
The presence of visitors did not affect activity levels.

The Impacts of a Commercial Bubble Curtain on Zoo-Housed African Penguin (Spheniscus demersus) Swimming Behavior (O'Brien & Cronin, 2023)

August 2023

Paper in JZBG: Can a commercial bubble curtain, which creates a stream of bubbles that generates water movement, increase swimming in zoo-housed African penguins?
Swimming behaviour of penguins observed and compared with bubble curtain on and off.
Bubble curtain did not increase swimming behaviour.
Most swimming behaviour observed at temperatures between −1 to −4 °C.

Battle of the enrichments: comparing the impact of nutritional and sensory enrichment on the behaviour of captive lowland tapirs Tapirus terrestris (Trelfa-Stewart & Cox, 2023)

July 2023

The behavioural effects of different types of enrichment on two zoo-housed lowland tapirs were investigated in a new paper in JZAR:
  Five nutritional enrichments + four types of sensory enrichment provided.
  All five nutritional enrichments positively affected feeding behaviours, but had no effect on locomotion or resting.
  Different enrichment strategies affected behaviour differently.
  Wide range of biologically-relevant enrichment is recommended.

Effects of honey locust seed pods on the behavior and nutrient intake of zoo-housed François langurs and prehensile-tailed porcupiness (Dunham et al., 2023)

March 2023

Can honey locust seed pods have an enriching effect on the behaviour and nutrient intake of zoo-housed langurs and porcupines? Yes, according to this new study in Zoo Biology:
  Langurs: Increased feeding, decreased stereotypies, no differences in nutrient intake.
  Porcupines: Increased feeding, decreased inactivity, differences in nutrient intake also detected.
  Fiber-rich honey locust seed pods may be beneficial for the nutrition and/or behaviour and welfare of zoo-housed folivores.

Effects of Failure on California Sea Lion (Zalophus californianus) Gameplay Strategies and Interest in a Cognitive Task: Implications for Cognitive Enrichment in Pinnipeds (Roberts et al., 2023)

March 2023

A study in JZBG investigated how failure during computerised cognitive enrichment affected the gameplay strategies of three sea lions:
 After failure, sea lions spent less time on each gameplay strategy, but increased the number of button presses - suggesting more precise movements.
Two of the sea lions exhibited an increase in interest (shorter latency without contact) in the enrichment after failure.

 Failure during cognitive challenges did not reduce gameplay performance or interest in enrichment.
 Individual variation in gameplay strategies: individual evaluation of enrichment use recommended.

Quantifying Acute Behavioral Reactions of Bali Mynas (Leucopsar rothschildi) to Environmental and Progressively Challenging Enrichment (Baskir et al., 2023)

February 2023

A study in JZBG investigated the effects of multiple enrichment items on the behaviour of zoo-housed Bali mynas:
Seven enrichment items, including modifiable bamboo tube with progressively challenging versions.
Feather plucking not affected by enrichment, as intended, BUT...
Locomotion increased, while autopreening, allopreening, and head bobbing decreased.
Leafy greens were the enrichment that caused the greatest changes in behaviour.
Interaction with bamboo tube was highest in the most difficult level (no habituation, perhaps decline in neophobic response).

Trainer Interaction Can Improve Welfare Outcomes of Toy Enrichment for Isolated Animals: A Case Study 
(Jaakkola et al., 2023)

January 2023

Can trainer interaction improve enrichment use in temporarily isolated animals? A case study on a bottlenose dolphin in quarantine was published in the JZBG:
Reduced floating in place, & increased enrichment use, after interaction with trainers.
Dolphin more likely to play with toys that had been used by trainer.
More research is recommended, but trainer interaction can potentially encourage enrichment use.

Cognitive Foraging Enrichment (but Not Non-Cognitive Enrichment) Improved Several Longer-Term Welfare Indicators in Bottlenose Dolphins (Clegg et al., 2023)

January 2023

How do cognitive and non-cognitive enrichment impact the welfare of captive bottlenose dolphins? A study in Animals found that in weeks with cognitive enrichment (rather than non-cognitive):
Dolphins engaged more with enrichment.
Increased motivation to participate in training sessions.
Decreased anticipatory & stereotypic behaviours.
Cognitive enrichment improved several welfare indicators & should be prioritised by zoos & aquariums.

Social structure and habitat design affect the impact of a novel feeding enrichment for alligators 
(Spain, Pearson & Rosenblatt, 2022)

November 2022

A study published in Zoo Biology tested the effects of a novel enrichment device, which attempted to simulate live prey, on the behaviour of zoo-housed American alligators:
Enrichment caused an increase in predatory behaviours in the dominant pair, but not in the three subordinates.
Behavioural effects of enrichment were not long-lasting.
Social structure & hierarchy may have affected enrichment use by subordinate females.
Recommendations provided to refine enrichment strategies in captive crocodilians.

An Improvement in Enclosure Design Can Positively Impact Welfare, Reduce Aggressiveness and Stabilise Hierarchy in Captive Galapagos Giant Tortoises
(Fieschi-Méric et al., 2022)

September 2022

The Galapagos giant tortoises at ZSL London Zoo changed to a more natural enclosure, and their behavioural responses to that change were assessed in a paper published in JZBG:
Habituation to new enclosure took six days;
Time budgets in new enclosure were closer to their wild counterparts;
Hierarchy changed and was more stable in new enclosure;
Decrease in interactions and agonistic encounters between individuals.
Appropriate enclosure design has positive effects on captive reptile behaviour & welfare.

The influence of olfactory enrichment on the behavior of two captive New World primates: Black-capped capuchin (Sapajus apella) and common marmoset (Callithrix jacchus) 
(Wowk & Behie., 2022)

September 2022

The effects of olfactory enrichment on the behaviour of two species of zoo-housed primates (black-capped capuchin & common marmoset) were investigated in a paper published in Zoo Biology
Decrease in inactivity observed in both species (capuchins responded to banana scent, marmosets to rosemary & deer urine);
Capuchins also showed more direct interactions with banana-scented cloth;
Habituation tests showed no significant changes during the study;
Olfactory enrichment can have positive impacts on animal behaviour & welfare.

An investigation of browsing enrichment, especially non-leaf foraging, on giraffes (Giraffa camelopardalis reticulata) at Kyoto City Zoo in Japan (Okabe et al., 2022)

August 2022

A paper in Zoo Biology looked into browsing enrichment in zoo-housed giraffes:
No differences in behaviour between green-leaf & deciduous phases;
Vegetation foraging decreased in deciduous phase, but dry hay foraging increased;
Twig & bark foraging increased in the deciduous phase for some individuals;
Giraffes foraged on twigs & bark of some tree species to compensate for the lack of leaves.

Foraging enrichment affects behaviour and enclosure utilisation in captive male gelada Theropithecus gelada
(Hurley & Cotton, 2022)

July 2022

A study in JZAR investigated the effects of a foraging enrichment device on the behaviour and enclosure use of a group of zoo-housed male geladas:
  Increase in time consuming food & foraging wild foliage;
  Foraging time budgets more similar to wild during enrichment;
  Greater enclosure use during enrichment.

Material and food exploration by zoo-housed animals can inform cognition and enrichment apparatus design
(Clark, Chivers & Pearson, 2022)

May 2022

A paper in Zoo Biology investigated how a group of zoo-housed ring-tailed lemurs explored novel materials & whole foods, to inform future cognitive apparatus:
 Preference to explore wooden surfaces;
 Metal produced too much heat & glare,  and untreated wood was easily destroyed by biting & chewing (materials to avoid);
 Olfactory exploration was more common than touch, but they used one or two hands for manipulation;
 Applications to cognitive research & enrichment.  

Environmental enrichment for collared peccaries Dicotyles tajacu, Tayassuidae in managed care: Different items provoke different behavioural responses (de Faria et al., 2022)

April 2022

A paper published in Journal of Zoo & Aquarium Research explored the effects of different enrichment items (basins with food, cardboard boxes with paper & food, scent trails, piles of straw with food) on the behaviour of captive collared peccaries:
 Exploration & behavioural diversity increased;
 Inactivity decreased;
 Straw pile and carboard boxes were particularly effective;
 Enrichment associated with food rewards had the most impact on behaviour;
 Applications to husbandry & welfare of this species in captivity.

Training as enrichment: A critical review (Fernandez, 2022)

February 2022

A paper in Animal Welfare reviewed the enrichment potential of training in captive animals::
 Three ways training may be enriching:
1. Facilitating the use of enrichment;
2. Modifying interactions;
  3. Expanding behavioural repertoires.
 Previous studies suggest the enrichment value of training, but further research is recommended.

Testing use of the first multi-partner cognitive enrichment devices by a group of male bottlenose dolphins (Matrai et al., 2022)

February 2022

A study in Animal Cognition tested a cognitive enrichment device that required cooperative manipulation on a group of five captive bottlenose dolphins:

A three-way and a four-way devices were created using PVC tubes equiped with rope handles and filled with fish and ice;

To open the devices, the dolphins had to pull the ropes simultaneously;

Dolphins received no previous training but were successful at opening both devices in 10 out of the 12 trials;

Interaction with the device observed during entire testing period , most of it was cooperative play.

Rehabilitation of Marine Turtles & Welfare Improvement by Application of Environmental Enrichment Strategies (Escobedo-Bonilla, Quiros-Rojas & Rudin-Salazar, 2022)

January 2022

A review in Animals discussed the importance of enrichment techniques in improving welfare & rehabilitation of marine turtles in short- and long-term captivity:

Five case studies reviewed;

Enrichment can improve welfare of marine turtles while in rehabilitation and promote natural behaviours;

Enrichment also improves chances of reintroduction success in physically damaged turtles or those in long-term captivity.

Environmental Enrichment Factors Associated with the Activity Level of Bottlenose Dolphins under Professional Care (Lauderdale et al., 2022)

January 2022

A new study in JZBG the relationship between the activity of captive dolphins and the buoyancy & provision schedule of enrichment:

Positive relationship between activity & duration of non-stationary enrichment;

Positive relationship between activity and larger number of enrichment types provided on rotation;

Negative relationship between activity and number of times sinking enrichment was provided;

Applications to enrichment programmes for captive dolphins.

Evaluating Environmental Enrichment Methods in Three Zoo-Housed Varanidae Lizard Species (Waterman et al., 2021)

December 2021

A study in JZBG evaluated enrichment methods in three zoo-housed Varanidae species:

Exploratory behaviour increased with scent piles, scent trails & hanging feeders;

Engagement with enrichment decreased over time;

No differences in engagement between scent and food-based enrichment - both effective;

Applications to husbandry of this poorly studied taxon.

Interest in coloured objects and behavioural budgets of individual captive freshwater turtles (Thomson et al., 2021)

November 2021

A paper in JZAR investigated a potential relationship between escape behaviour in captive freshwater turtles & their interest in coloured objects:

High & moderate escape behaviour: more interest in coloured objects & reduced escapes in their presence;

Low escape behaviour: less interest in the objects & increased escapes in their presence;

interest in yellow objects with more contacts before feeding & at start of observation period.

Applications to turtle enrichment programmes.

The effect of different types of environmental enrichment on Humboldt penguin Spheniscus humboldti behaviour (Razal & Miller, 2021)

November 2021

A study in JZAR investigated the effect of enrichment on the behaviour of zoo-housed Humboldt penguins:

Enrichment tested: (𝟏) artificial sticks, (𝟐) live minnows, (𝟑) floating island, (𝟒) feeding penguins in water;

Artificial sticks significantly increased activity levels;

No significant differences detected for other enrichment types.

Investigating the Effect of Enrichment on the Behavior of Zoo-Housed Southern Ground Hornbills
(Brereton, Mayhill & Shora, 2021)

November 2021

New paper in JZBG looked into the effects of enrichment on the behaviour of zoo-housed southern ground hornbills:

Three types of enrichment: pile of twigs, small animal carcasses & plastic mirrors;

Carcasses & mirrors caused the greatest behavioural changes;

Carcasses: long periods of food manipulation;

Mirrors: stalking around & pecking, similar to "window smashing" wild-type behaviour;

Both food-based and non-food enrichment can be beneficial to zoo-housed animals;

The natural history of a species can inspire effective enrichment strategies.

Should zoo foods be chopped: macaws for consideration (James et al., 2021)

November 2021

New study in JZAR looked into the effect of food presentation (whole and chopped fruit) on the behaviour of two pairs of zoo-housed blue-and-gold macaws:

Keepers spent significantly more time preparing diets with chopped fruit;

Activity budgets mostly the same in both food presentation regimes BUT...

Podomanipulation (i.e. foot use) and allofeeding significantly higher when whole fruit was presented;

Resting/inactivity significantly lower with whole fruit presentation;

Providing macaws with whole foods may be time-effective for animal care staff while encouraging wild-type feeding behaviours & reducing inactivity in the parrots.


Photo: Beale Wildlife Park

Knowledge-based enrichment: Development of a novel enrichment device for captive chimpanzees 
(Brooks, Yoshimura & Taki, 2021)

May 2021

A study in Zoo Biology tested a knowledge-based enrichment device on two groups of captive chimpanzees, where they had to retrieve small tubes containing hidden treats from a large tube:
Group with NO experience with the device: LOWER interaction than "knowledgeable" group UNTIL an individual retrieved first tube;
Rapid knowledge transmission between group members seemed to have occurred;
Individuals spent >20 minutes on average interacting with device (one-hour observation periods);
Knowledge can motivate enrichment use even when food rewards are not visible.

Enrichment devices for green turtles (Chelonia mydas) reared in captivity programs (Kanghae et al., 2021)

May 2021

A new study in Zoo Biology tested the effect of several enrichment devices on the behaviour, health and welfare of captive young green turtles, raised in a head-starting programme:

Enrichment caused a decrease in biting wounds;

More interactions with ring-shaped enrichment than hollow-square, sphere and cylinder shapes;

Growth & feed utilisation not affected by enrichment;

Ring-shaped enrichment was the most effective.

An evaluation of interactive projections as digital enrichment for orangutans (Carter et al., 2021)

January 2021

A study in Zoo Biology investigated the use of interactive projections as digital enrichment for zoo-housed orangutans:

Varied interactions with the enrichment were observed, especially among the younger individuals;

Digital enrichment did not have any significant effects on the orangutans' time budget;

Interactive projections do not require food rewards as motivation.

Effects of Enclosure and Environmental Enrichment on the Behaviour of Ring-Tailed Lemurs (Lemur catta)(Laméris et al., 2021)

April 2021

A study in JZBG looked into the effects of type of enclosure and enrichment on the behaviour of zoo-housed lemurs:

Type of enclosure had stronger effects on behaviour than enrichment;

The effect of enrichment on behaviour differed between indoor and outdoor enclosures;

Enrichment programmes should be evaluated and not generalised across enclosures.

The Effects of Live Feeding on Swimming Activity and Exhibit Use in Zoo Humboldt Penguins (Spheniscus humboldti) (Fernandez et al., 2021)

March 2021

New paper in JZBG looked into the effects of live feeding (trout) on the swimming activity and enclosure use of zoo-housed Humboldt penguins:
>30% total swimming increase in live feed days;
Increased (overall) enclosure use in live feed days;
Live feeding may be an effective enrichment strategy in this species.


Photo credit: Woodland Park Zoo

Exploring How White-Faced Sakis Control Digital Visual Enrichment Systems (Hirskyj-Douglas & Kankaanpää, 2021)

February 2021

Research published in Animals investigated the use of an interactive video device as enrichment for saki monkeys at Korkeasaaren eläintarha:

Device gave sakis the choice to trigger different videos;
Underwater & worm videos triggered more than others (animals, abstract art, forest);
Scratching, which is potentially stress-related, decreased;
Device use eventually decreased - habituation?
Device potentially enriching, but challenges of quantifying interactions discussed.

Can colored object enrichment reduce the escape behavior of captive freshwater turtles? (Bannister et al., 2021)

February 2021

A new study in Zoo Biology looked into the effects of enrichment (coloured objects, with & without fish scent) on the behaviour of aquarium-housed freshwater turtles:

Presence of coloured objects reduced escape behaviour;

Fish-scented objects attracted more interest;

Large individual differences in the behavioural response to enrichment;

Fish-scented, coloured objects have the potential to be beneficial for captive turtles, but individual monitoring is recommended.

Assessing preferences of two zoo‐housed Aldabran giant tortoises (Aldabrachelys gigantea) for three stimuli using a novel preference test (Learmonth et al., 2020)

December 2020

A case study investigated the preferences of two Aldabran giant tortoises for three different stimuli/enrichment (human interaction, food and a red boomer ball):

One tortoise preferred food + ball while avoiding human interactions altogether;

The other tortoise preferred food + human interactions;

Stimuli/enrichment preferences show individual variation and depend on several factors.


Photo credit: Zoos Victoria

Using longitudinal data to evaluate the behavioural impact of a switch to carcass feeding on an Asiatic lion (Panthera leo persica) (Finch et al., 2020)

October 2020

What is the long-term behavioural impact of carcass feeding on zoo-housed Asiatic lions? A lioness at Chester Zoo showed the following behavioural changes 12 months after the diet change:
Reduction in pacing;
Increase in resting behaviour;
Increase in feeding-related behaviours, shortly after & 12 months after the diet change.


Photo credit: Chester Zoo


A persistent abnormal repetitive behaviour in a false water cobra (Hydrodynastes gigas) (Michaels et al., 2020)

November 2020

Fresh new paper looked into stereotypic behaviour in captive false water cobras:
Observed fixed pattern of movement against viewing window identified as potential stereotypy;
Snake spent some time in this repetitive behaviour, which was also reported by another zoo;
The enrichment used did not reduce the behaviour's frequency or changed the snakes' use of the enclosure.


Photo credit: Smithsonian's National Zoo


Development of an environmental enrichment programme: case study of white Bengal tiger (Panthera tigris bengalensis) and jaguar (Panthera onca) at Moscow Zoo (Podturkin & Papaeva, 2020)

April 2020

A study investigated the effect of daily and every other day enrichment provision on the behaviour of a zoo-housed tiger and jaguar, using a time efficient, keeper-friendly, methodology:

Increase in enrichment-directed behaviours in both animals;

No significant effects on general activity - small sample size?

Methodology allowed keepers to implement & evaluate enrichment programme.

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