The migratory monarch butterfly (Danaus plexippus plexippus), known for its spectacular annual journey of up to 4,000 kilometres across the Americas, has entered the IUCN Red List of Threatened SpeciesTM as Endangered, threatened by habitat destruction and climate change.
All surviving sturgeon species - also migratory, found across the northern hemisphere - are now at risk of extinction due to dams and poaching, pushing the world's most Critically Endangered group of animals yet closer to the brink. The tiger (Panthera tigris) has been reassessed, revealing new population figures.
The IUCN Red List now includes 147,517 species, of which 41,459 are threatened with extinction.
“Today's Red List update highlights the fragility of nature's wonders, such as the unique spectacle of monarch butterflies migrating across thousands of kilometres,” said Dr Bruno Oberle, IUCN Director General. “To preserve the rich diversity of nature we need effective, fairly governed protected and conserved areas, alongside decisive action to tackle climate change and restore ecosystems. In turn, conserving biodiversity supports communities by providing essential services such as food, water and sustainable jobs.”
The Endangered migratory monarch butterfly is a subspecies of the monarch butterfly (Danaus plexippus). The native population, known for its migrations from Mexico and California in the winter to summer breeding grounds throughout the United States and Canada, has shrunk by between 22% and 72% over the past decade. Legal and illegal logging and deforestation to make space for agriculture and urban development has already destroyed substantial areas of the butterflies' winter shelter in Mexico and California, while pesticides and herbicides used in intensive agriculture across the range kill butterflies and milkweed, the host plant that the larvae of the monarch butterfly feed on.
Climate change has significantly impacted the migratory monarch butterfly and is a fast-growing threat; drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies.
The western population is at greatest risk of extinction, having declined by an estimated 99.9%, from as many as 10 million to 1,914 butterflies between the 1980s and 2021. The larger eastern population also shrunk by 84% from 1996 to 2014. Concern remains as to whether enough butterflies survive to maintain the populations and prevent extinction.
“It is difficult to watch monarch butterflies and their extraordinary migration teeter on the edge of collapse, but there are signs of hope. So many people and organisations have come together to try and protect this butterfly and its habitats. From planting native milkweed and reducing pesticide use to supporting the protection of overwintering sites and contributing to community science, we all have a role to play in making sure this iconic insect makes a full recovery,” said Anna Walker, member of the IUCN SSC Butterfly and Moth Specialist Group and Species Survival Officer at the New Mexico BioPark Society, who led the monarch butterfly assessment.
The global sturgeon reassessment published today reveals that 100% of the world's remaining 26 sturgeon species are now at risk of extinction, up from 85% in 2009. The assessments are based on refined calculations which show their decline over the past three generations to be steeper than previously thought. The Yangtze Sturgeon (Acipenser dabryanus) has moved from Critically Endangered to Extinct in the Wild, 17 species are now Critically Endangered, three are Endangered and five are Vulnerable on the IUCN Red List. The reassessment has also confirmed the extinction of the Chinese Paddlefish (Psephurus gladius).
Renowned for their size, with the Critically Endangered Beluga (Huso huso) growing up to eight metres and 1,700 kilograms, sturgeons have been overfished for their meat and caviar for centuries. Despite being protected under international law, poaching continues to affect more than half of these species; stronger enforcement of regulations on the illegal sale of sturgeon meat and caviar is critical to stop further declines. Dams affect all sturgeon species migrating to their breeding grounds, while rivers warming due to climate change further disrupts sturgeon reproduction. Freshwater ecosystem restoration and building effective fish passages, together with restocking, which has already proven effective for species such as the Critically Endangered Adriatic sturgeon (Acipenser naccarii), are key measures to support the long-term survival of the world's sturgeons.
The tiger has been reassessed, with new figures revealing that there are currently between 3,726 and 5,578 tigers in the wild worldwide. The 40% increase since the last tiger assessment in 2015 is the result of improvements in monitoring, showing that there are more tigers than previously thought, and the number of tigers globally appears to be stable or increasing. While this reassessment confirms that the tiger remains Endangered on the IUCN Red List, the population trend indicates that projects such as the IUCN Integrated Tiger Habitat Conservation Programme are succeeding and recovery is possible as long as conservation efforts continue.
Major threats include poaching of tigers, poaching and hunting of their prey, and habitat fragmentation and destruction due to the growing pressures of agriculture and human settlement. Expanding and connecting protected areas, ensuring they are effectively managed, and working with local communities living in and around tiger habitats, are critical to protect the species.