The Serious Side of Poo In The Zoo

Scientists reveal the serious side of Poo at the Zoo as a celebration of the bestselling book comes to Chester Zoo.

From February 14 to March 16, a trail based around Poo at the Zoo, a popular children’s story written by Steve Smallman and illustrated by Ada Grey, will allow young Chester Zoo visitors to explore the varied world of animal droppings.

There will be fun and educational events and activities, including a poo trail, daily poo parties, zoo ranger events and an appearance from Robbie the Robot, who comes equipped with a vacuum cleaner to suck up poo.

It will be a month of dung discovery for children aged 3-6, but scientists at Chester Zoo, a registered conservation charity, have already been investigating animal droppings for more than a decade, with incredible results.

Faecal samples from threatened species are sent to the Zoo’s lab for testing, with the aim of reversing extinction. 

Veronica Cowl, Reproductive Biology Coordinator at Chester Zoo, and Isabel Callealta, postdoctoral research fellow, work with more than 25 zoos, safari parks and wildlife reserves across Europe to increase the chances of more tigers being born.

They will test thousands of tiger droppings over the next 20 months.

Amur and Sumatran tigers are critically endangered, and only 600 of each species are estimated to remain in the wild. These tigers are proving particularly difficult to breed in human care. 

Veronica said: “It's not an exaggeration to say that improved breeding outcomes are a vital part of making sure these species have a secure future. Hormone testing might provide an answer.”

Faecal samples from male and female tigers are carefully shipped to Chester Zoo, where they are dried and sifted to produce pure faecal powder. These samples, now easier to reliably measure, are tested for the presence of reproductive hormones.

Veronica said: “Once analysed, they give us a great snapshot of which tigers are ready to breed now, which may change decisions related to breeding, and will allow us to guide organisations in how to improve breeding success for the animals in their care.”

Tigers are not the only source of scientifically interesting scat. Zoo scientists also analyse samples from endangered Sulawesi lowland anoa, a buffalo species which may number fewer than 5,000 in the wild, and okapi, a close relative of the giraffe, which are also endangered.

In 2024, Chester Zoo processed 865 samples from okapi and 1,100 samples from anoa. Testing continues in 2025.

Chester Zoo conservation scientist John O’Hanlon said: “For many species, ensuring we have healthy populations in human care is not as easy as placing a male and female together and hoping they produce offspring. It is a skilful balance of expertise in animal husbandry, species genetics and understanding their reproductive mechanisms.

“This individual testing feeds into a larger research project to understand what normal reproductive patterns look like for a species. We can only diagnose pregnancy and support breeding programmes when we understand a species’ reproductive physiology.”

One of the advantages of faecal sampling is that the material is plentiful. Picking up these samples is sometimes smelly work, but it is far less invasive than blood tests, reducing stress on the animals under observation.

One of Chester Zoo’s early successes came in 2012 with the birth of an okapi calf at the zoo itself. Now the team is testing hormones in samples sent in from Ireland, Germany, the Netherlands and further afield to support okapi breeding and is working with nine partner zoos in Europe to help boost anoa numbers. Zoo scientists are also working with partners in Africa to roll out methods in the field to protect species in the wild.

For more information about research and conservation projects at Chester Zoo, visit www.chesterzoo.org/conservation-science-education