For the first in its history, the Budapest Zoo and Botanical Garden have welcomed birch mice to its terrariums. In early June, researchers collected two pairs of Hungarian birch mice from the grassland of Borsod County. These mice were taken to the Budapest Zoo, so that the behaviour and lifestyle of these unique animals could be observed. But our goal is more ambitious: establishing a captive population to enable conservation of the species. Let’s take a brief look at why keeping this endangered and highly protected species in terrariums is so important.
The species of Hungarian birch mouse (Sicista trizona) can be found only in two places in the whole world: near city of Cluj (Kolozsvár) in Romania and in the grasslands of Borsod County in Hungary. These two populations differ from each other at sub-species level; they are neither genetically nor taxonomically identical. They were also given a separate name: Hungarian birch mouse (Sicista trizona trizona) and Transylvanian birch mouse (Sicista trizona transylvanica).
Only one isolated population of the Hungarian birch mouse is still existent. This subspecies is particularly vulnerable. Any further adverse conditions effecting the remained population could lead to the extinction of the subspecies. But the situation is not yet fatal. According to species surveys, the Hungarian birch mouse is relatively common in the grasslands of Borsod County - this enables us to collect a few specimens every year, to study them in captivity under controlled conditions. Our knowledge about the lifestyle and reproduction of the birch mouse is very vague, so keeping them in captivity is the only way to conduct long-term population ecological studies and to plan conservation measures.
The question may arise, why the birch mouse can’t be considered as a simple mouse that has long been kept and bred for experimental purposes? The birch mouse is not a “real mouse”, but belongs to a very ancient super family of rodents and only distantly related to any mouse species. The birch mice have a very different lifestyle to real mice, and their behaviour is unique: they eat a lot of insects, they are astonishingly mild-mannered. Unlike real mice, female birch mice come into season only once each year. They might well have more unique characteristics, which have not yet been observed. Until now, they didn’t show any interest in mating and breeding in captivity. Getting birch mice to breed in captivity is challenging for all the researchers, conservationists and zoologists involved.
On the morning of 21 June 2021, Ms. Judit Pivarics and Mr. András Benyó, the professionals of the Budapest Zoo shared the miraculous news with other Hungarian zoos: one of their young, female birch mice had given birth to healthy pups. According to their estimation, the number of the pups was between three and five, but the exact litter size couldn’t be determined precisely, because the staff didn’t want to touch the mice and they arranged complete peace for them. It was very difficult to look inside the nest, but on the backs of some one-week-old pups a long stripe became visible, which acts as camouflage in grasslands. They started to open their eyes at 17 days old. They developed rapidly, so they became mobile enough to leave the nest and roam toward the terrarium at 25 days old. The first litter inspection took place on 29th of July, when the youngsters were counted: 5 mice had been born and raised, and they were named after famous rodent stars in the Hungarian cartoon Cat City.
The Budapest Zoo and Botanical Garden ensured a peaceful environment for the 5 pups of the first litter born in captivity to grow up. The video was taken after the first litter inspection, when the experts took the animals out from the terrarium and then counted and weighed the offspring. For the duration of the inspection, the youngsters, together with their mum, were placed in a temporary terrarium, where the video was taken.
The program is managed by the Bükk National Park Directorate. The Budapest Zoo and Botanical Garden, the Hungarian Natural History Museum, the Bükk Mammalogy Research Group Society and the MTA-DE Evolutionary Phylogenomics Research Group took an active role in the implementation of the program. The project (LIFE IP GRASSLAND-HU - LIFE17 IPE / HU / 000018) is funded by the European Union's LIFE Program and co-financed by the Ministry of Agriculture.
Source: Hungarian Natural History Museum