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An orange, black and cream colored butterfly perched on a yellow flowering plant
Information icon Puerto Rican harlequin butterfly. Photo by Jan Zegarra, USFWS.

Proposed threatened listing under the Endangered Species Act for the Puerto Rican harlequin butterfly, along with proposed Critical Habitat and 4(d) Rule

What is the Puerto Rican harlequin butterfly and where does it occur?

The Puerto Rican harlequin butterfly is a medium-sized butterfly in the checkerspot family that is native to Puerto Rico. The butterfly’s distribution is fragmented among remnants of native forest in northwestern and southwestern Puerto Rico.

What action is the U.S. Fish and Wildlife Service taking?

Based on a review of the best available scientific and commercial information, the U.S. Fish and Wildlife Service (Service) is proposing to list the Puerto Rican harlequin butterfly as threatened under the Endangered Species Act (ESA). The Service is proposing to designate approximately 41,266 acres of critical habitat in Puerto Rico as well as a special 4(d) rule that tailors protections for the butterfly while allowing activities that do not harm its recovery.

Why is the Service proposing to list the Puerto Rican harlequin butterfly as a threatened species?

Today, six populations of the Puerto Rican harlequin butterfly are known to exist, each generally small in size with less than 100 total individuals observed in any given year. Relative to historical conditions, the butterfly’s distribution is fragmented among remnants of native forest located in northwestern and southwestern Puerto Rico.

Habitat modification, fragmentation and losses caused by urban development and agricultural practices are the main reasons for this butterfly’s decline and threats to its continued existence. Other threats affecting the butterfly include human-induced fires, improperly applied pesticides, herbicides and fungicides, and clearing of native vegetation. Small population sizes, which are natural but exacerbated by human-caused threats, along with reduction in range and lack of population connectivity, also threaten the species. Climate change is also considered to be a future threat to the species, with increased temperatures, drought, and storm frequency and intensity projected for Puerto Rico.

How does the ESA define critical habitat?

The ESA defines critical habitat as the specific geographic areas that contain features essential to the conservation of an endangered or threatened species that may require special management and protection. Critical habitat may also include areas that are not currently occupied by the species but will be needed for its recovery.

Establishing critical habitat for the butterfly will alert federal agencies that they are required to make special conservation efforts when they work, fund or permit activities in these areas. The designation will have no impact on private landowners taking actions on their land that do not require federal funding or permits.

How does the Service determine what areas to designate as critical habitat?

Within areas occupied by the species, biologists consider physical or biological features needed for life processes. These include:

  • Space for individual and population growth and for normal behavior;
  • Cover or shelter.
  • Food, water, air, light, minerals, or other nutritional or physiological requirements;
  • Sites for breeding and rearing offspring.
  • Habitats that are protected from disturbances or are representative of the historical geographical and ecological distributions of a species.

After considering occupied areas, biologists consider unoccupied areas that may be essential for the conservation of the species.

What is the proposed critical habitat designation for the Puerto Rican harlequin butterfly?

The proposed critical habitat for the butterfly is limited to occupied areas where the species currently occurs. This includes a two-kilometer buffer around breeding sites. In total, approximately 41,266 acres are being proposed – 56 percent in private ownership; 39 percent owned/managed by Puerto Rico Department of Natural Resources; and 5 percent other (e.g. – municipality, other). Since all proposed critical habitat is currently occupied by the species, most or all of the protections or changes in management will be the same as those provided for the species’ conservation under the ESA.

The critical habitat being proposed is in units, in the municipalities of Isabela, Quebradillas, Camuy, Arecibo, Utuado, Florida, Ciales, Maricao, San Germán, Sabana Grande and Yauco. The map below shows where those units are located.

Map showing proposed critical habitat for the Puerto Rican Harlequin butterfly
Proposed critical habitat for the Puerto Rican harlequin butterfly in Puerto Rico

Ownership of the proposed critical habitat units is as follows

Unit Number/Name Occupied Landowner/Land Manager(s) Area (acres)
Unit 1. IQC Yes Municipality recreational area 5
Private 1670.7
Unit 2. Guajataca Yes PRDNER 583.5
Private 3,255.5
Unit 3. Río Abajo Yes PRDNER 4,544.4
Private 1,394.8
Unit 4. Río Encantado Yes PLN (Private conservation organization) 1,442.6
PRDNER 204.8
Private 11,128.2
Unit 5. Maricao Yes PRDNER 7,883.1
Private 2,971.5
Unit 6. Susúa Yes PRDNER 3,171.5
Private 3,010.4
Total N/A N/A 41,266.0

What is a 4(d) rule? Why is this being proposed for the Puerto Rican harlequin butterfly?

For threatened species, the Service uses the flexibility provided under section 4(d) of the ESA to tailor the take prohibitions to those necessary and advisable for the conservation of the species. This targeted approach helps reduce regulatory burdens by exempting certain activities that do not significantly harm the species, or that are beneficial, while focusing conservation efforts on the threats detrimental to recovery.

The 4(d) rule for the Puerto Rican harlequin butterfly will include an exception for federal and commonwealth (Puerto Rico Department of Natural and Environmental Resources) agency conservation activities, including collection of broodstock, tissue collection for genetic analysis, captive propagation, and stocking into currently and historically occupied areas. The following exceptions are also being considered: (1) reforestation projects that promote the establishment or improvement of habitat conditions for the species by the planting of native trees and the host plant Oplonia spinosa, selective removal of exotic trees, seasonal pruning of native and exotic vegetation, or a combination of these; (2) non-native species removal (e.g., invasive grass) and agricultural pest monitoring; and (3) fire prevention programs.

How do I submit comments on this proposal?

Comments on the proposed rule must be received by 11:59 p.m. Eastern Time on 12/14/2020 (60 days after publication in FR). We must receive requests for public hearings, in writing, at the address shown in FOR FURTHER INFORMATION CONTACT by 11/27/2020 (45 days after publication in FR).

You may submit comments by one of the following methods:

  1. Electronically: Go to the Federal eRulemaking Portal. In the Search box, enter FWS–R4–ES–2020–0083, which is the docket number for this rulemaking. Then, click on the Search button. On the resulting page, in the Search panel on the left side of the screen, under the Document Type heading, check the Proposed Rule box to locate this document. You may submit a comment by clicking on “Comment Now!”
  2. By hard copy: Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS–R4–ES–2020–0083, U.S. Fish and Wildlife Service, MS: BPHC, 5275 Leesburg Pike, Falls Church, VA 22041–3803.

We request that you send comments only by the methods described above. We will post all comments on This generally means that we will post any personal information you provide us (see Public Comments, below, for more information).

Availability of supporting materials: For the critical habitat designation, the coordinates or plot points or both from which the maps are generated are included in the administrative record and are available at and at under Docket No. FWS–R4–ES–2020–0083, and at the Caribbean Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT). Any additional tools or supporting information that we may develop for the critical habitat designation will also be available at the Service website and Field Office set out above, and may also be included in the preamble and/or at

For Further Information Contact

Edwin Muñiz, Field Supervisor, U.S. Fish and Wildlife Service, Caribbean Ecological Services Field Office, P.O. Box 491, Road 301 Km 5.1, Boquerón, Puerto Rico 00622; telephone 787–851–7297. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Relay Service at 800–877–8339.

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