Swainson’s Hawk Delisting Prompts Conversation Among Wildlife Biologists
A recent proposal to remove the Swainson’s Hawk from the California Endangered Species Act has sparked a debate about the species' current status and recovery progress.
In June 2026, the California Building Industry Association submitted a petition requesting that the Swainson’s Hawk (Buteo swainsoni) be delisted under the California Endangered Species Act (CESA). First enacted by the State of California in 1970, the California Endangered Species Act establishes legal protections for species designated as threatened or endangered and provides a framework for their conservation and recovery to prevent further decline and extinction. As of 2026, CESA protects approximately 250 species, with only six species officially delisted or removed from the list since 2005. (California Department of Fish and Wildlife, n.d.).
The California Fish and Game Commission designated the Swainson’s Hawk (Buteo swainsoni) as a threatened species in 1983 following substantial population decline and widespread habitat loss. More than four decades later, the recently submitted petition argues that the species has recovered sufficiently to no longer warrant threatened status. The petition states that California’s Swainson’s Hawk population has rebounded beyond estimated historical levels and that many previously identified threats are no longer significant.
To formally delist a species from CESA, a petition must provide scientific evidence on population trends, survival and reproductive success, distribution and range, the effectiveness of current management actions, and the severity and immediacy of existing threats to show that delisting is justified. The current petition presents evidence across these areas and relies on chosen studies and reports to support its conclusion that delisting is warranted.
Among the cited research is foundational work by longtime raptor biologist Dr. Peter Bloom, whose studies of Swainson’s Hawks date back to the 1970s. Dr. Bloom’s early research helped document both the species’ historical distribution and the substantial decline observed by the late 1970s. The petition compares those historical estimates with more recent population estimates when evaluating the species’ recovery. Following Bloom Biological’s integration into Endemic Environmental Services, Dr. Bloom continues his work alongside Endemic’s biological team, focusing on recent efforts to identify, capture, tag, and track new individuals across Central California and the Antelope Valley.
While extensive scientific data exists from research completed in Central CA, a data gap remains for other parts of the species’ historical California range. Areas including Southern California, the Coast Ranges, Great Basin, and Mojave Desert remain important when considering statewide distribution and recovery. The petition itself acknowledges that the species’ current breeding range does not extend throughout the full range estimated in Bloom’s earlier research. Bloom advises that additional surveys and long-term research across these regions can improve understanding of the Swainson’s Hawk’s current status in California, allowing biologists to draw more accurate conclusions about the species.
For Endemic Environmental, our goal is to continue contributing reliable field data and long-term biological expertise to the broader scientific understanding of the Swainson’s Hawk. By building on decades of research with ongoing studies of the species today, we hope to support informed, science-based decisions that promote the long-term success of Swainson’s Hawks throughout California. As research continues, we hope all data are properly analyzed, and the best decisions are made to support the success of the Swainson’s Hawk, California wildlife, and residents of the state.
Citations
California Department of Fish and Wildlife. (n.d.). Threatened and endangered species: Protected under the California Endangered Species Act. https://wildlife.ca.gov/Conservation/CESA
