The monarch butterflies of the west of the US reach their second lower population figure in almost three decades
A drastic decrease in the population of Monarch butterflies that pass the winter in the west of USA He has turned on the alarms among conservation experts. As reported CBS Newsthe most recent count made by the Xerces Society for Invertebrate Conservation He revealed that in 2024 there were barely 9,119 copieswhich represents a decrease in 96% compared to 233,394 counted in 2023. This number is the Second lower since 1997only surpassed by the historical minimum of 1,901 butterflies in 2020.
The situation is especially worrying in key sites as a reserve of the Nature Conservancy in Santa Barbara, Californiathat last winter she housed 33,200 butterflies And this year he barely received 198. This massive decline highlights the multiple threats facing these butterflies, known for their orange and black wings, and that were declared Endangered species by the International Union for the Conservation of Nature (IUCN) In 2022.
Western monarchs usually migrate from the northwest of the United States and southwest Canada Towards the coast of California To spend the winter in areas where the weather is more temperate. Historically, millions of copies congregated in the forests of eucalyptus and pines of this region, creating impressive colonies. However, the drastic reduction of its numbers has made many traditional hibernation sites almost empty, also affecting ecological tourism that depends on the arrival of these insects.
The disappearance of the Asclepiaessential plant for monarchs, is one of the main factors that explain this crisis. According to the organization Monarch Joint Venturethis plant has been severely affected by the drought, forest fires, agricultural expansion and urban development. In addition, the use of pesticides It has contaminated much of the plants that still survive, which aggravates the situation.
He Climate change He also plays a crucial role. The monarchs need specific temperature and precipitation conditions to complete their life cycle, from the egg to the adult butterfly. However, the Extreme heat waves registered in the west of the US in 2023, with temperatures that exceeded the 40 ℃ (104 ℉) And they even reached 51 ℃ (124 ℉) in Palm SpringsThey have hindered reproduction and survival. As explained Emma Peltonbiologist of endangered species society, temperatures higher than 38 ℃ (100 ℉) They can slow their reproduction, while those above 42 ℃ (108 ℉) They are lethal for these insects.
The impact of these extreme conditions is not limited to the west monarchs. In a festival held in Minneapolis in September 2023several attendees commented that they had noticed a decrease in the number of butterflies compared to previous years, as reported CBS News Minnesota. Wendy CaldwellExecutive Director of Monarch Joint Venturesaid that this perception is consistent with the data that show a downward trend in the populations of monarchs throughout the continent.
Despite the seriousness of the situation, experts maintain some hope. Monarch butterflies have The ability to experience a exponential growth in their populations under the appropriate conditions. An example of this occurred after the historical minimum of 2020, when the west population recovered until reaching 247,246 copies in 2021an increase in almost 13,000%. However, Pelton warned that a bad year, like the current one, can have a significant impact on long -term recovery.
“This is bad news”, affirmed PELTON“But we have seen incredible recoveries. This does not mean that west monarchs will disappear, but it should be a call for attention to how vulnerable they are to changes in their environment. ”
In this context, the US Fish and Wildlife Service announced in December 2024 that he is working to include monarchs in the list of threatened species. This designation would prohibit actions such as the elimination of asclepias on private land and protect 1,778 hectares (4,395 acres) in Seven Coastal Counties from California which serve as hibernation sites for the west monarchs. Although this measure would not prevent development in these areas, landowners with federal permits would have to coordinate with the agency for minimize habitats damage.
The conservation of monarch butterflies not only depends on government actions, but also on public participation. As he said Martha Williamsdirector of the US Fish and Wildlife Service“The iconic monarch butterfly is appreciated throughout North America, captivating children and adults with their fascinating life cycle. Despite its fragility, it is remarkably resilient, like many things in nature, when we give them a chance. ”
In this sense, the environmental organization Earthjustice presented a request in December 2024 so that the Environmental Protection Agency (EPA) requires evidence on the effects of pesticides on insects such as Bees, moths and butterflies. This initiative seeks to address one of the most critical problems faced by monarchs and others essential pollinators For ecosystems.
The period of public comments on the proposal to include the monarchs in the list of threatened species will end in March 2025and the final decision is expected to December of this year. Meanwhile, experts and conservation defenders urge to take Immediate measures To protect these butterflies, whose survival is intrinsically linked to the health of ecosystems and biodiversity in general.
