Summer is in full bloom and butterflies are already here - colorful, ethereal, almost invisible - they fit naturally into the beautiful summer landscape. In recent years, their flight through the meadows of Europe, including Bulgaria, has become increasingly rare. Although they are fragile in appearance, they are among the most important indicators of the state of nature. At the same time pollinators, food for other animals and a signal for deeper ecological problems, they are vital for nature and for us - as part of this nature. Their disappearance is not just an aesthetic loss, but an important warning. Climate change, intensive agriculture and habitat loss are already negatively affecting dozens of species on the map of Europe, according to the latest research data. And Bulgaria, with all its natural wealth, is no exception.
At the same time, good practices for the conservation of many butterfly species have already been developed on the old continent, and this successful experience should be implemented in Bulgaria as coordinated strategies.
The effect of climate change on insects in Bulgaria has not been sufficiently studied. If we take into account the European experience, zoos and nature parks in our country could actively engage in the conservation of this species. It is also necessary to strengthen control over the use of pesticides, as well as more care and space for green urban areas.
Why butterflies are important for ecosystems
Butterflies show how healthy an ecosystem is – and it depends on this whether it will survive climatic shocks.
These insects undergo metamorphosis: the adult animal (imago) flies and feeds on nectar, which it obtains from flowers and thus pollinates flowering plants. This symbiosis is of great importance, because a large part of plant species are entirely dependent on pollinators for their reproduction and genetic wealth.
The butterfly larva - the caterpillar, occupies a different niche. Most caterpillars feed on the leaves of plants. Usually these plants are different from those that are pollinated. In this way, caterpillars have an impact on plant communities and contribute to their diversity. They are not pests in the natural context.
Most species of butterflies overwinter as pupae. Under suitable climatic conditions, they transform into flying butterflies. Caterpillars and adult insects are key to the food chain, because many animals feed on them, such as songbirds.
Butterflies are also part of the landscape. Many of the species have beautiful colorful colors and have a positive effect on the human psyche and health.
Caterpillars can be extremely diverse and beautiful, just like adult insects. Source: Pavel Vassilev
How climate change affects butterflies
Climate change is already among the top 3 threats to butterflies in Europe, ranking, according to the European Red Book of Butterflies, after the intensification of agriculture and the abandonment of suitable habitats. Climate change negatively affects nearly 20 endangered and nearly 20 non-endangered species on the continent. The effects significantly affect the biogeography of flora and fauna, that is, their distribution. Changes in vegetation can occur too quickly, which does not allow animals to adapt. This, together with the isolation of many animal populations from each other and the lack of wildlife corridors, can lead to extinction.
Mild winters negatively affect tundra species such as the garden tiger moth Arctia caja. This species overwinters as a caterpillar, which is adapted to frosty winters, and is unable to survive in mild wet winters. Between 1968 and 2002, the number of this species fell by 89% in the UK, and this trend is expected to continue, according to data from the British organization Butterfly Conservation. She reports that warm-loving species are expanding their range, such as the lime nightjar Mimas tiliae, while cold-loving species are migrating to colder places, which is not always possible.
A study by the Entomological Institute “Senkenberg Müncheberg“, Germany, conducted with data from 1900 to 2022, indicates that climate change is affecting European butterflies living at medium altitudes. The study shows that they start flying much earlier in the year. This is due to short winters and rising temperatures, which leads to an earlier start to the spring season. Some species become active throughout the spring and summer. This is not the norm - in general, butterflies fly for only two or three months, when they lay eggs, after which they die. Scientists say that this will upset the balance established thousands of years ago. New clashes are expected between different species that would fly at different times of the year. However, the study does not see a difference in their behavior in high mountains. There, it is not temperature that is key to insect activity, but the amount of precipitation, which has not decreased in the higher parts.
Although direct human activity has the strongest negative effect on insects, climate change has an additional negative impact on them. Butterflies are considered to be of two main types: narrow specialists, surviving in only one type of habitat, and generalists, which are found in more than one habitat.
Specialized species are most seriously threatened by habitat loss, but there is also a decreasing number of so-called generalists. This is most likely due to a combination of factors.
All species suffer from the use of insecticides and herbicides. Agriculture, fighting the elimination of “pests“, also harms harmless species. Intensive agricultural practices, reduced grazing and fragmentation of the landscape with roads and plantations put butterflies under threat, and climate change is putting additional stress on most species.
What is the diversity in Europe and in Bulgaria?
Butterflies are a very diverse group of insects. The most common representatives of this order are butterflies and moths. Worldwide, the number of butterfly species is about 150,000.
The southern European mountains are considered the richest in species - the Pyrenees, the Alps and the Balkans.
Bulgaria is in 5th place in terms of the number of butterfly species - 211 species, according to the European Red Book of Butterflies. The top countries are Italy (264), France (244), Spain (243) and Greece (230).
There are 50 important areas for butterflies in Bulgaria.
What is the trend on the continent and in Bulgaria?
According to the European Red Book of Butterflies from 2010, there are no accurate studies on the development and distribution of butterflies in many Eastern European countries. However, it has been established that about 9% of species are threatened with extinction in Europe, 7% - in the European Union. Of the European species, 31% have decreasing populations, 4% have increasing populations, and more than half - with stable populations. 10% of species have an unknown trend. The largest number of endangered species are found in Eastern Europe.
And in Bulgaria?
According to a list published in 2017 by the National Museum of Natural History at the Bulgarian Academy of Sciences, 215 species have been identified in the country, with every fifth of them threatened with extinction (21%).
The 2015 Red Book of Bulgaria lists:
2 species as extinct: big-eyed satyr Lopinga achine and marsh satyr Coenonympha oedippus;
4 species as important for conservation: Dardanian blue Agriades dardanus, Maturna Euphydryas maturna, Red Apollo Parnassius apollo and Balkan yellowtail Colias caucasica.
According to data from the Bulgarian-British Society, which organizes butterfly observation excursions in Bulgaria every Since 2002, 216 species have been recorded in the country, with 5 most likely extinct.
What are the measures in Western Europe?
Butterfly conservation requires monitoring, which consists of assessing the status, diagnosing the problem, testing a solution, managing restoration actions, which ultimately leads to sustainable and effective management of the species and the places it inhabits.
Butterfly Conservation is a good example, working with landowners.
The experts at this organization provide advice and work on the development of new conservation measures. The rarest species are prioritized. The organization manages areas throughout the UK, which are placed in one of three categories - high priority landscape, priority landscape and priority site.
An example of the challenge of butterfly conservation is the conservation of the white admiral species Limenitis camilla - found in Europe, including Bulgaria, its habitat is deciduous and mixed forests. It is vulnerable due to its dependence on the honeysuckle plant Lonicera periclymenum - a type of climbing shrub in the elder family. The caterpillars hatch and feed on it, but only if it is partially shaded. If it is exposed to the sun, it becomes unsuitable, and there is no alternative. For adult individuals, it is important to have open sunny areas and a rich range of flowers. With sudden and unpredictable changes in climate, these nuanced habitats can change dramatically. Therefore, it is important to maintain such habitats both in nature reserves and in tree plantations.
What can be done in our country?
What policies can change things
Bulgaria still does not have a national plan for the protection of wild pollinators - despite clear scientific recommendations. There is a plan created by the scientific community and non-governmental organizations, but it has not been adopted by the relevant institutions. There is also a lack of initiatives to draw attention to the need to protect wild pollinators.
29 species are protected by the European Union Habitats and Wild Fauna and Flora Directive and are therefore included in the National Biodiversity Strategy. Although of great importance, this plan is not ideal. According to the report by the Institute for European Environmental Policy (IEEP), not all species in need of protection are included in it.
The latest action plan is for the butterfly Nymphalis vaualbum, which enters into force in 2024 and is valid until 2033. The plan assesses the degree of impact of climate change on the species as potentially high and unstudied.
Bulgaria has a butterfly monitoring network, which belongs to the European Butterfly Monitoring Network (eBMS).
Without accurate maps and data, there is no effective protection
Butterflies are among the best-studied insects, but there is still a lack of sufficient data for some regions, including Bulgaria. Regular field surveys are needed, especially outside the Natura 2000 protected areas – in settlements and agricultural areas, where the risk to butterflies is greater.
Reliable monitoring and mapping allow the implementation of effective measures for endangered species. Outside protected areas, two unfavorable trends are observed: intensive agriculture and complete abandonment of areas - both of which harm butterflies, with the former having more serious consequences.
There is a lack of studies on the impact of climate change in Bulgaria, especially in urban and rural areas. “Heat islands” are already forming - environments poor in native vegetation and water bodies, with strong light pollution.
Although difficult to predict, the effects of climate change can be mitigated by creating and protecting suitable habitats. The organization Butterfly Conservation calls on both professionals and amateur gardeners to take action to protect these valuable insects.
The role of zoos in butterfly conservation
Modern zoos around the world - in cooperation with scientific institutes - have the potential for scientific research related to climate change and butterfly conservation. Many tropical butterfly species can be raised and bred in humane conditions, which may even allow the creation of reserve populations. There are zoos specializing in the presentation of butterflies - the so-called "butterfly houses". They have a very high pedagogical potential, because they allow visitors to enter the habitat of these species. Unfortunately, however, a large part of these zoos are purely commercial and do not work with international zoo associations. Tropical butterflies are the main target of “butterfly houses”, because they are larger and more attractive to visitors. There is still little work with native European species, but scientists see potential in this.
Natural solutions and actions on site
One of them is the sowing or grafting of plants that are used either by the adult or the larva of a given species. For this purpose, careful study of the species in a given area and their needs is necessary. It is also important that these interventions are legal and do not remove rare plants from protected areas, nor do they introduce alien species. If everything is done properly, new habitats can be successfully created or existing habitats expanded. This is achievable in both urban and rural settings.
It is important to have nectar sources available from early spring to late fall. This can include plants from the rose family - rose hips, apples, cherries, as well as from the asteraceae family - daisies, chamomile, chicory, etc.
Nettle is a preferred plant for caterpillars. It is important for the species peacock eye Aglais io, nettle butterfly Aglais urticae and admiral Vanessa atalanta. Species such as the mourning dove Nymphalis antiopa and the polygon Polygonia c-album like to feed on fermented fruits.
Butterflies need a mosaic of tall trees, shrubs, grasses, flowers and bare soil. Therefore, attention should be paid to mowing and weeding in city parks and country yards. Ryegrass areas are not suitable habitat for butterflies, so experts recommend leaving unmowed corners or mowing higher so that low flowers can bloom. Butterflies are still not a target of Bulgarian zoos, but the opportunity is there. The so-called practice of rewilding butterflies is rarely used, but has great potential. It represents coordinated breeding programs of endangered species, which can allow further release into new habitats.
The study and conservation of butterflies is possible, as long as there is a desire and attitude towards these extremely valuable and beautiful animals. Their conservation also means the conservation of many other plants, insects, birds, reptiles and mammals. With increasing changes in climatic conditions, their protection is becoming increasingly urgent, and suitable habitats must be created and maintained, both in wild natural areas and in every yard, garden, forest and field.