At Parques Reunidos, we believe that true care for animals goes beyond daily attention. It means understanding their wellbeing through science.

This belief has guided an exciting new study led by the Autonomous University of Barcelona and professionals from several zoos, including our very own Zoo Aquarium de Madrid. Together, the team has achieved a global scientific milestone: developing the first non-invasive method to measure oxytocin levels in fecal samples, using lions as the model species.

A New Way to Understand Animal Wellbeing

Oxytocin, often known as the “bonding hormone”, plays a vital role in social behavior, stress regulation, and emotional connection. Until now, studying it required invasive procedures such as blood collection, which could affect the results.

By validating fecal oxytocin as a reliable biomarker, researchers have found a gentle, stress-free way to assess animal welfare, opening the door to new, positive indicators of wellbeing across species.

Collaboration for Conservation

This pioneering study, carried out in five Spanish zoos, involved collecting samples from 16 male and female lions living in stable social groups. The findings confirm that oxytocin can be consistently detected in feces, providing valuable insights into how animals experience both social bonds and environmental conditions.

The project represents a major step forward for ethical animal management and reinforces the role of modern zoos as centers of scientific research and conservation.

In Conversation with Eva Martínez, Veterinarian at Zoo Aquarium de Madrid

What does this research mean for the future of animal welfare in zoos?
This study is a big step forward because it helps us measure not only stress but also positive emotions. We can now understand how animals feel in a much more complete way, and most importantly, without disturbing them.

How challenging was it to collect and analyze samples from lions?
It required coordination, patience, and great teamwork. The key was to collect samples naturally, without any change to the animals’ daily routines. Every sample tells a story about how the lions are living and interacting in their environment.

What are the next steps in this line of research?
The goal is to refine the method and apply it to other species. Understanding oxytocin better could help us make evidence-based improvements in animal management, from habitat design to social grouping.

At Parques Reunidos, we are proud to support teams that combine passion for animals with scientific excellence. This collaboration between universities and zoological institutions in Spain reflects our shared commitment to continuous improvement, innovation, and the wellbeing of every species under our care.

Together, we move closer to a future where animal welfare is understood, measured, and enhanced through science.