Current work in wildlife, rivers, public lands, and climate

SANTA FE, N.M. – Today, the U.S. Fish and Wildlife Service (Service) published a proposed rule to list the eastern regal fritillary (Argynnis idalia idalia) as an endangered species and to list the western regal fritillary (A. i. occidentalis) as a threatened species under the Endangered Species Act (ESA). WildEarth Guardians petitioned the Service to list the regal fritillary under the ESA in 2013. 

“In protecting the regal fritillary, we are not only preserving a unique and beautiful species but also safeguarding essential pollinators that are vital to human health and agriculture,” said Joanna Zhang, endangered species advocate at WildEarth Guardians. “These butterflies, along with other pollinators, play a crucial role in the productivity of our crops and the resilience of our ecosystems.”

In 2020, as the Service was well over its two-year deadline for a listing decision, the Center for Biological Diversity filed a lawsuit to hold the Service accountable for determining whether the regal fritillary, among 241 other species, should be protected under the ESA. 

“The regal fritillary is an amazing and beautiful butterfly that deserves protection, but it’s troubling that hundreds more species are still waiting for badly needed safeguards,” said Jess Tyler, a staff scientist at the Center for Biological Diversity. “It shouldn’t take 11 years to protect any species. The Fish and Wildlife Service’s listing program needs reform and more money from Congress to meet the extinction crisis head-on.”

The regal fritillary is a large, nonmigratory butterfly found in open grassland habitats. Historically, this pollinator was common across 32 states.  The eastern subspecies has been extirpated in its entire range except 457 acres of grassland in the Fort Indiantown Gap National Guard Training Center in Pennsylvania. The western subspecies is found in fragmented populations across 14 states (Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, South Dakota, Wisconsin, and Wyoming). The two subspecies are genetically and physically distinct, and separated by approximately 540 miles, so exchange between the two is highly unlikely. 

Distinguished by its orange forewings and blue-black hindwings with black bars, fine white markings, and two rows of large spots, the regal fritillary is similar in size to the monarch butterfly, with a wingspan ranging from 2.67 to 4.13 inches. 

The western regal fritillary is primarily threatened by the loss and fragmentation of native prairie grasslands due to agricultural conversion and development. The broad application of herbicides also poses a major threat to the western regal fritillary, as it reduces the availability of violets and other nectar sources, and herbicides may also be directly toxic to individuals. 

Both subspecies are threatened by drought and other climate change factors, the encroachment of woody vegetation and invasive plants, as well as disturbances such as fires and mowing. These habitat impacts have resulted in smaller, more isolated populations, making genetic exchange and dispersals resulting in successful recolonization challenging. Protecting and restoring large, high-quality grasslands, along with enhancing habitat connectivity, will be crucial for the long-term survival of this species.

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