There are many reasons why Butterflies, Both during the day and nightly are important. They have value for themselves, but they are Excellent indicators for environmental quality and ecosystems in general.
Insects are the most numerous species group among animals. The Butterflies They are the Third order, after Coleoptera and Hymenoptera, with a larger number of species in all biodiversity. They represent about two -thirds of all species.
The rich areas in Butterflies They are also in other invertebrates. Many offer together Environmental benefits, including pollination and natural pest control. Many plants, predators and parasites are strictly dependent on species or specific groups of Butterflies
Butterflies versus drought
The latest data presented by the Butterflies Monitoring Program of Catalonia, The Catalan Butterfly Monitoring schedule (CBMS)They reveal that the period 2021-2023 has been the least abundance Butterflies Because it is being followed and that the 2024 has confirmed 210 local extinctions of population Butterflies Coinciding with the period of continuous drought that was lived on our territory.
This kind of extensions are considerably multiplied compared to previous years. Nevertheless the arrival of Rains on 2024 marked a first rebound for Catalan butterflies after three years of drought. In Global, more than half of the species (52%) increased their populations the previous year, while 48% dropped.
The CBMS, coordinated by the Museum of Natural Sciences of Granollers and promoted by the Generalitat de Catalunya and the Diputació de Barcelona, Recoce Datos de Butterflies Since 1994 up to and including weekly counts made by voluntary persons. The Transects are repeated every year and can detect population changes and trends.
Weld Butterflies are one of the most reliable indicators around the world to measure the loss of biodiversity In open spaces and the state of health of nature in general, and for this reason CBMS works in a coordinated way with the rest of the European followers of UPS or Butterflies
The data collected by this project is the key to evaluating the Natuurstaat in Catalonia, and therefore this is one Project linked to Natural Heritage Observatory and Biodiversity.
Local butterflies extinction
Catalonia suffered a persistent drought between 2021 and 2024. Although the May 2024 rained abundantly, but irregularly, this has not been sufficient to prevent the accumulated impact. This has done that Many butterfly populations have had their effects and they have stopped detecting in many network transects.
“He Status of vegetation is the key to the development of butterflies. A decrease in the quantity or quality of resources when it does not rain has an impact on the larvae when they feed or adults because of the availability of flower nectar. ‘Andreu Ubach says Van de Museu de Ciències Naturals or Granollers.
For 30 years of Follow -Up, extinction and colonizations have been observed in the field of territory, but the situation this last year is a drastic change in the collected data. Between 2021 and 2023, very low abundance of individuals were already detected in many transects, but it is believed that a Butterfly is extinguished when it is detected after 4 years in a row after 4 years in a row during the next 4.
“This does not mean that if the circumstances improve, this species cannot appear occasionally and can be found again when transects are repeated in the future,” Andreu adds. That’s why, A local extinction is reversible if the species in the city continues to existHe concludes.
The data Patent the largest local extinction of butterflies in Catalonia since it has registered: Since 1994, 495 local extinctions have been counted, of which 210 were confirmed in 2024. This does not mean that these species have disappeared this year, but that four years have not detected any transects where they were before. That is, the effect of drought is manifested late.
One of the most affected species is the dark Kobout (Cupid14 extinction), the pin (Fabriciana Adippe10), the pear of the bushes or laurel (Brenthis Daphne10), La Boloria him10 and the gold of white spots (Hesperia Comma9). Much of these mainly took place in the Mediterranean area, while in many cases the Alpine populations of these species remain stable.
Local phenomena and regional trend
On the other hand, 2024 The CBMS has calculated trends at Catalan level for a total of 145 species. At a general level, 68 species (56.55%) are observed in moderate or strong regression, 15 species (10.34%) in moderate or strong increase, 33 (22.75%) in a stable situation and 15 (1.34%) with an uncertain tendency. Together, trends are negative logical with 113 species (77.9% of the cases) and positive in 32 (22.1%).
Loose Being able to fluctuate changes from one year through the other in most invertebratesBecause every year it is a new generation that is born as a result of the climatic and landscape effects produced. To the sampling points that have successive data (2023-2024), the global abundance has grown by 8%, from 199,000 to 215,000 people. This advance, but part of historic minima achieved 2022 and 2023, so that it will have to consolidate it in the coming years.
The weather is crucial
Although the drought in recent years has caused the local extensions of Butterflies, not all species have had negative consequences. Depending on their life cycle, the way they grow and reproduce, some have even benefited.
Spring rains at 2024, for example, were good for Butterflies That fly in the summer and have more than one generation in the year (polyvoltinas) Because their larvae found more food in the spring.
On the other hand, many of those who fly to spring had already been The previous year found because they were larvae, they found very little food because of the strong drought collected at 2023. This has made species such as Tomillera (Pseudopilots panoptes), The Aurora (Anthocharis -ARTAMIJNS) O on Olmera (Nympalis Polychloor), they suffered important decreases.
On the other, There are butterflies that winter as adults and then, with good spring conditionsThey were able to successfully reproduce the summer of 24. Some species benefited from this fact were Cleopatra (Gonepteryx cleopatra), the Mariposa Del Almez (Libythea Celtis) O to Mariposa C-Blanca (Polygonia C album).
The results are not the same everywhere: they are much dependent on the climate of each area. Since 2020, the CBMS analyzes the Butterflies Separately in three large climatic areas: the Alpine and Subalpine area, the moist Mediterranean Sea and the dry Mediterranean Sea. If you want to see how each evolves, The results are for every species on the CBMS website.
In 2025: What will happen?
It is clear that the rains from 2025 have to reverse a drastic situation of low abundance and extensions Butterflies, But it is still early to draw conclusions. On the one hand, the Spring species that started with historical minima last year have not been recoveredBecause in some cases his flight period has been shortened by the constant rains and even it can be thought that the mortality in those species caused that winter like a chrysi because of an increase in the attack of parasites or fungi.
But everyone who will now get it will clearly benefit from the state of vegetation and we are waiting for a summer full of butterflies. We should think that on the one hand the following programs try to understand the reason for the fluctuations year after year of these species, but that it is the trend that tells us about the present and the future of each of the species.