We thank Nico Le Si Min for appreciating the work of the animal care team at Wildlife Reserves Singapore (WRS), and our role in protecting wildlife and ensuring the long-term survival of threatened species in the letter "Do zoo animals have enough space?" (May 3).

WRS uses an evidence-based framework to evaluate an animal's level of welfare, similar to like-minded modern zoos.

Because an animal's welfare depends on the sum of interactions with its surroundings, this framework, based on the "Five Domains Model", takes into account multiple areas that affect the animal's emotional status, namely environment, nutrition, physical health and ability to express natural behaviours.

Every animal in our care is regularly assessed by a team of wildlife professionals.

The above model allows us to evaluate whether our animals are thriving and alerts us to possible areas for improvement.

WRS believes animal habitats should offer choices for the animals to express a wide range of natural behaviours and afford mental stimulation.

We design our exhibits based on the species' natural history and match habitat possibilities with species needs.

This may include the tiger's penchant for a swim to cool down or the cassowary's preference for a quick dip before dwelling in dense vegetation.

More than just the physical dimension, the richness and dynamism of the living space is of equal, if not greater, importance.

To enhance the animals' living environment, our carers regularly provide them with enrichment opportunities to further stimulate their mental and physical capacities.

We hope this alleviates any concerns regarding our animals' quality of life.

Cheng Wen-Haur (Dr)

Deputy Chief Executive Officer and Chief Life Sciences Officer

Wildlife Reserves Singapore