The garden dormouse (Eliomys quercinus) has been disappearing from Eastern and Northern Europe since the 1950s, and was last seen in the wild in Estonia in 1986.
Now, the aim is to re-establish the population, using animals bred at Tallinn Zoo, with the small Pakri Islands off Paldiski set to be the initial venue. The dormice will be microchipped.

The idea was under discussion as far back as the 1990s, but turning ideas into action took quite some time. The current initiative was the brainchild of former Tallinn Zoo director Tiit Maran, and the project is being led by Auli Veske.

"Last year, the zoo approached the University of Tartu with the idea that since we've managed to successfully keep and breed dormice at the zoo, perhaps there might be some enthusiastic people at the university willing to launch such an ambitious project in their free time. And there were such enthusiastic people," Veske told "Ringvaade."

A successful dormouse reintroduction program is currently underway in the Netherlands, and Veske said she had observed this too. "We've visited our Dutch colleagues, and our zoo's dormice actually originate from there," Veske noted.

Up to now, 35 individuals are being nursed: The original number had been 41 but six were lost over the winter hibernation season, a figure Tallinn Zoo conservation specialist Kristel Nemvalts said was not too bad considering how long and cold the 2025–2026 winter was.

"During the first winter we were a bit worried and monitored them very closely. We had cameras in their enclosures, observed how often they woke up, and weighed them regularly," Nemvalts said.

The zoo's conservation center, not open to the public, is the animals' current home, with houses set up with their behavior in mind.

"It is very important that there's a sufficiently thick layer of soil inside the house, as dormice like to burrow underground for hibernation. We'll also add 'furniture' — branches they can climb on — and special nesting boxes designed for dormice, where they can sleep during the day and give birth to their young," Veske noted.

The dormice need their space, too. "If we want to breed them, we can only place one pair in each enclosure," Nemvalts added.

The species was not adequately studied and understood in the past, so it is not clear why they disappeared from Estonia's ecology, though this may well have been due to Soviet-era pesticides. "As insectivores, dormice ate poisoned insects, and toxins accumulated in their fat reserves — which they rely on during winter — leading to a sharp population decline," Veske said, adding she "hoped" that was the case, as such chemicals are not used anymore, meaning the numbers would not decline for that reason after being reintroduced.

Veske said "in an ideal world" the release of the chipped dormice would only need to happen once, adding that in reality, this needs to be done repeatedly, year on year, as this is a learning curve for both humans and dormice.

Another success story which can be leaned on comes with European mink. "They've been reintroduced to Hiiumaa and Saaremaa, and they're doing quite well there," said Tallinn Zoo director Kaup Heinma.

One interesting fact about the dormice is the animal's name in Estonian – lagrits – literally "licorice," a reference to the species' black eye markings.

"On the other hand, maybe it draws people in and makes them curious — what kind of 'licorice' is going to live on the Pakri Islands? First of all, they're just incredibly cute. They simply are! Furry, curled up sleeping together with other dormice," Veske noted.

Another interesting find came when the animals went under UV light at the zoo — causing their fur to glow. "We don't know the reason. There are several hypotheses. The effect is caused by porphyrins in their fur, which break down in sunlight," Nemvalts explained. "It's not even clear whether this is a useful trait. It may simply be a byproduct of metabolism," Veske added.

Despite its name, the garden dormouse mainly inhabits forests, and also fruit-growing regions. It is nowadays more common in southwestern Europe and in alpine regions. It is not found in the U.K. or Ireland.

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