False ringlet returns to former habitat after 10 years
Ig, 17 August - The Iški Morost natural reserve in the Ljubljana marshes has again become home to a butterfly species known as the false ringlet, one of Europe's most endangered daytime butterflies. Researchers of the Jovan Hadži Institute of Biology at the ZRC SAZU have successfully reintroduced it to the area, where it was last seen 10 years ago.
The reintroduction of the false ringlet (Coenonympha oedippus) to the Ljubljana marshes is part of activities aimed at salvaging the species in central Slovenia and is one of the first measures of its kind both in Slovenia and widely, explained Tatjana Čelik of the Jovan Hadži Institute of Biology, who has played a key role in the project.
Čelik said the false ringlet is among the 15 most endangered daytime butterflies in Europe, with 80% of its population disappearing in the past few decades.
While it used to be present more widely both in the Ljubljana marshes and central Slovenia in general, the species was almost completely exterminated by unfavourable conditions. These were created mostly by the intensification of farming, while climate change is also a growing risk. Only a single group can be found in this area today and it is in danger of extinction.
The reintroduction project sought to address this problem and strengthen this sole group. The project started last June and at the start of July this year the first stage was completed with the settlement of 175 pupae that had been raised at a butterfly farm. The final number of hatched butterflies will mostly depend on environmental factors, Čelik said, explaining that 168 had hatched until the final June days, at least 70% of which successfully. "We meanwhile cannot tell this year yet how many of the successfully hatched butterflies will actually mate and contribute towards the next generation," she added.
The reintroduction process
A special butterfly farm was established for the project at the Barje Research Station with all the requisite infrastructure that secures conditions emulating those in nature. Vegetation from the butterfly's natural environment was installed into six insectariums, special flooding tables made sure the atmosphere remained humid, while a special shading system and mesh panel walls preserved a natural climate.
The researchers borrowed fertilised females from the original location in the Ljubljana marshes to return them after the eggs were hatched in the insectariums. The development of the butterflies in the insectariums from eggs, to larvae and pupae, was closely monitored by researchers from June last year to May this year.
In May and June, 20 of the 175 pupae were returned to the original group, while the remaining 155 were transferred to the reintroduction point in the Ljubljana marshes, where a special reintroduction tent was set up for a transitional stage. The tent helped the hatched males and females find each other easier and lay new eggs. The entire procedure will be repeated this year, Čelik said.
Years of research experience are an advantage
The Slovenian researcher has been dedicating her time to the false ringlet for 25 years. The species was the subject of her master's and PhD theses, which is why this project means a lot to her.
She feels that years of experience with this species are a major advantage, since procedures like reintroduction require extremely in-depth knowledge of the species's biology and of the ecological characteristics of the original group. "We've learned a fair bit in 25 years, which is why we also could and dared to take on this project," Čelik said.
The importance of the reintroduction for the ecosystem
According to Čelik, reintroduction is a process that environmentalists turn to as a very final resort. But due to the impact of humans, urbanisation and intensive farming, species have had a hard time surviving in their natural environment without human help and are on the brink of extinction.
"Reintroduction is one of the ways of saving a species or part of its population from extinction. This also means simultaneously salvaging the entire ecosystem surrounding these species," Čelik explained.
This is especially true for the false ringlet, she added, arguing the species was a good indicator for such wet grasslands poor in nutrition. "If we create a habitat for the false ringlet we will also create it for many other extremely endangered humidity-loving plant and animal species."
The false ringlet is not the only endangered specifies in Slovenia. There are about 30 daytime butterflies on the red list out of 180 living in Slovenia.
The false ringlet
The false ringlet is a daytime butterfly from the nymphalidae family and is found in areas ranging from the Pyrenees in the west to the north-east of China, Korea and Japan in the east. It is mostly found in isolated groups in Europe.
Two ecotypes of the false ringlet can be found in two distinct environments. In the coastal region of Primorska, the false ringlet is found on dry, overgrown meadows on flysch and limestone soil, and in central Slovenia (the Ljubljana marshes) on wet meadows with purple moor-grass and in alkaline fens.
The false ringlet is protected by the Habitats Directive and the Bern Convention, while in Slovenia the species and its habitats are legally protected with the regulation on protected species of animals living in the wild.
Researchers of the Jovan Hadži Institute of Biology at the ZRC SAZU have been striving for the expansion and reintroduction of the false ringlet as part of the PoLJUBA: Rehabilitation and Conservation of Wetland Habitats in the area of Ljubljana Marsh Nature Park project, which is managed by public institute the Ljubljansko Barje regional park.