Hermes Copper Butterfly May Be Listed as a Threatened Species–What that Means for Your Projects

Close up of an orange and black butterfly perched on the leaves of a plant

On January 8, 2020 the U.S. Fish and Wildlife Service (USFWS) officially published proposed rules for listing the Hermes copper butterfly (Lycaena [Hermelycaena] hermes), a species endemic to San Diego County and northern Baja California, Mexico, as threatened under the Endangered Species Act (ESA). The proposed rule also designates 35,211 acres of Critical Habitat in San Diego County and outlines exceptions to the ESA for certain permissible activities.

Where does the Hermes copper butterfly occur?

Hermes copper butterfly (Hermes) adults are active May through July, when females deposit single eggs exclusively on their host plant, Rhamnus crocea shrubs (spiny redberry), in coastal sage scrub and chaparral vegetation (Hermes eggs remain in a period of suspended development (diapause) during the late summer, fall, and winter). The butterfly’s primary nectar source is the shrub Eriogonum fasciculatum (California buckwheat), although other nectar sources can provide equivalent or supplemental adult nutrition. Hermes copper butterflies do not stray far from their host plant and nectar sources, though they have been recaptured up to 0.7 miles from the point of release. Given their singular host plant, the need for nectar sources near that plant, and their tendency not to disperse, suitable habitat for the Hermes copper butterfly is finite.

There are 95 (92 in the U.S.) known historical or existing Hermes copper butterfly occurrences in the U.S. and northwestern Baja California, Mexico; only 45 sites––all in the U.S.-–-still exist or are presumed to still exist. Of the remaining known occurrences, 40 are presumed destroyed and 10 are permanently destroyed. Habitat/species destruction is due to five threats, outlined by the USFWS, including:

  • Wildfire. Fire can have devastating effects, as it has the potential to destroy both habitat and the species quickly and concurrently.
  • Drought. Drought can exacerbate the effects of fire, limiting recovery and promoting weed growth. Further, it can affect the health of host plant species.
  • Land use change. Urban development in San Diego County results in loss, fragmentation, and isolation of habitat and connections between habitat blocks.
  • Habitat fragmentation and isolation. Habitat fragmentation and isolation occur both permanently (development) and temporarily (fire), when otherwise suitable habitat is blocked from occupied habitat.
  • Climate change. While the connection between climate change and Hermes copper butterfly declines are not well known, shifts may have an effect on emergence from diapause and other factors.
Graphic outlining the 5 threats facing the Hermes copper butterfly.
Key threats facing Hermes copper butterfly and its habitat include wildfire, drought, land use change, habitat fragmentation and isolation, and climate change.

What has USFWS defined as Hermes critical habitat?

Critical habitat is land within or near the geographical area occupied by the species (at listing time), where key life requirements are met, and where additional management or protections are required. The USFWS’ critical habitat unit boundaries for the Hermes copper butterfly, include:

  • Lopez Canyon Unit (410 acres)
  • Miramar/Santee Unit (7,092 acres)
  • Southeast San Diego Unit (27,709 acres)
Map of San Diego County showing Hermes copper butterfly critical habitat units and areas exempt from take prohibitions. The legend reads: Lopez Canyon Unit (410 acres), Miramar/Santee Unit (7,092 acres), Southeast San Diego Unity (27,709 acres)
The USFWS has identified three critical habitat units, as well as areas exempt from take prohibitions for Hermes copper butterfly throughout San Diego County.

Are any activities exempt from permit requirements?

4(d) rules outline how and where the prohibitions of Section 9(a)(1) of the ESA will be applied. The USFWS’ proposed rules for listing Hermes include 4(d) rule provisions/exclusions, detailing certain activities that are allowed to occur without a permit. Potential taking of the species may occur within the exemption zones when certain activities are underway, such as:

  • Scientific studies
  • Habitat management intended to recover species
  • Some fire management or suppression activities.

Other activities deemed to cause little risk to Hermes are also excluded from permit requirements. These activities include:

  • Normal agriculture
  • Forest management
  • Landscape maintenance
  • National Parks recreation and management

However, permits would be required for any unauthorized handling and modification, removal, or destruction of spiny redberry within the species’ range that is known to be occupied by Hermes copper butterfly and that may result in death or injury of adults, eggs, larvae, or pupae.

What are the next steps?

This proposed rule affects most of the natural lands east of the developed areas in San Diego County. If finalized, the USFWS will likely develop official species survey protocols that may be similar or different from the current ones. Any impacts to Hermes’ host plant and/or nectar plants would likely trigger the need for coordination or consultation with the USFWS, particularly if those areas are within 1 kilometer of known occupied areas.

A 60-day comment period is open to gather feedback on the proposed rules. Dudek biologists will continue to monitor the process. If you think your current or future project may be affected by the potential listing of the Hermes copper butterfly as Threatened, contact us. Our permitted biologists and butterfly experts can perform surveys and are adept at USFWS regulatory compliance and permitting, if needed.

Contact us for more information.