What Is Environmental Enrichment?

Environmental enrichment is the practice of adding objects and other stimuli (environmental enrichment devices, or EEDs) to the surroundings of captive animals to encourage them to express natural behaviours. Enrichment aims to improve quality of life and promote positive animal welfare by providing both mental and physical stimulation.

There are five broad types of environmental enrichment: nutritional, sensory, cognitive, social, and physical habitat.
Although there is a degree of overlap between categories, diverse types of enrichment will encourage different behaviours.

Why Do We Need Enrichment?

Animals naturally express a wide range of behaviours to forage for food, interact socially, build shelter, or find a mate. In captivity, if animals do not have the resources or opportunities to perform these activities, they can become frustrated and stressed, and may develop abnormal behaviours.

Enrichment encourages normal behaviours, including mental activities to stimulate curiosity, and physical activities that also improve fitness. In a rehabilitation setting, enrichment specifically helps to prepare the animal for release back into the wild.

Our Study, Environmental Enrichment for Rehabilitation in Sea Turtles (Maldives)

May to July 2022

To find out how turtles interact with diverse types of environmental enrichment, we have designed an exciting experiment. We have made three different enrichment devices, each falling within a different enrichment category, which we are placing in the pools with our turtles.

To avoid disturbing the turtles and influencing their behaviours, we are filming each session remotely. Once we have captured sufficient video footage, we can analyse the interactions to assess if different turtles prefer different devices, and if there is an overall favourite.

As some of our patients suffer from buoyancy syndrome and struggle to dive, our enrichment devices have been designed to be easily accessed from the water surface level. Results will be used to improve our enrichment strategy and optimise our turtles’ welfare.

This work is designed to build on the findings from our previous work in 2020 (see below). We have developed our methods slightly but are using a similar framework and analysis technique to measure behaviour. By advancing our previous work, we aim to find out more about sea turtle behaviour in captivity.

Our Novel Enrichment Objects

• Pipe – floats on the water surface, filled with food to stimulate foraging behaviour and provide nutritional enrichment. Once the food is exhausted, it continues to provide sensory stimulation.
• Log – adds physical structure to the turtle enclosure, designed to provoke exploratory behaviours and provide tactile stimulation.
• Square – provides sensory and tactile enrichment. The turtles can manipulate it with their flippers, climb through it and rub their shells against it.

Although we are only using three novel enrichment objects for this study, our turtles interact daily with other EEDs such as: floating balls, shelters, shell-scratchers, fishy ice-blocks, and other types of food dispenser.

September 2020

For all of our patients, we provide a stimulating environment to encourage curiosity and natural behaviours. We have started to enhance our environmental enrichment plan, to use a larger variety of different objects to stimulate the senses. Objects such as PVC frames,  floating balls, and brushes are being presented to the turtles for tactile stimulation. To simulate foraging and hunting behaviours, we are giving foods in ice blocks (‘fish popsicles’), and using a variety of floating devices to encourage interaction and problem-solving.

October 2020

We are presenting our turtle residents with a variety of novel Environmental Enrichment Devices (EEDs) or ‘pool toys’, to stimulate their curiosity and their senses. We are characterising the behaviours of our turtles both with and without enrichment. We use video recordings and ethograms (behaviour catalogues) to evaluate the effectiveness of the various EEDs.
So far, we have recorded 20 short video clips for 4 Olive Ridley turtle patients, to study behaviours when presented with:

• an empty pool, without any added enrichment devices;
• 3 different food-delivery systems (plastic lid, rotational pipe, floating pipe);
• 3 different objects (PVC frame, plastic balls, brush).

We have recorded raw data from the control videos and four of the enrichment devices, and we are creating ethograms to evaluate the effectiveness of the devices. Using continuous sampling, the footage is being evaluated by timing the different behaviours:
– pattern swimming, oriented behaviour (interaction with the enrichment device), random swimming, resting.

November 2020

Video clips were recorded for all four patients, without enrichment, and again with the 6 different enrichment devices in turn, in order to characterise the different types of turtle behaviours. Ethograms were created to evaluate the effectiveness of the enrichment devices. Using continuous sampling, the footage was evaluated by timing the 4 main different behaviours we observed:

• repetitive pattern swimming,
• focused/oriented behaviour (interaction with the device and grooming),
• random swimming around the pool,
• resting on the water surface.

• Without enrichment, our turtle subjects spent most time ‘pattern swimming’ (75%) and ‘resting’ (20%).
• With enrichment, ‘pattern swimming’ (40%) and ‘resting’ (1%) were much reduced as expected, with more time spent ‘oriented’ (40%) towards the devices, and ‘random swimming’ (20%). This behaviour shift was consistent for all 4 turtle patients, although variations in behaviours towards the different enrichment devices was recorded, likely due to their different personalities.

The results of our pilot study show that environmental enrichment can be effective in increasing activity and exploratory behaviours in captive sea turtles. A changing environment provides turtles with the opportunity to make behavioural choices based on the assimilation of new information, and the ability to satisfy curiosity about new stimuli. Because of this, it is important to maintain novelty, which can be achieved by providing enrichment for short periods in rotation (as inquisitive initial behaviours may lessen with familiarity). The varied responses seen between the turtles serves to highlight the importance of tailoring enrichment devices to each turtle’s preferences.

Overall, positive behavioural changes were seen in all four turtles, so we will continue to develop and implement enrichment devices to improve the psychological and physiological well-being of our rehabilitation patients.

Pictured below, interacting with their environmental enrichment ‘toys’: Frisbee – Varu – Thaku – April