Island Marble Butterfly endangered but...

Photo by Susan Vernon  Spiders and wasps prey on them,  deer and rabbits munch on their habitat, and Congressional budget cuts work against them. The status of the rare Island Marble Butterfly, the very small population at American Camp on San Juan Island is likely the only remaining population of the subspecies, warrants that the species be added to the Endangered Species List.  However budget constraints mean higher priorities preclude its addition to the list. 

The U.S. Fish and Wildlife Service published its  12-Month Findings on Petitions To List April 5, 2016 in the Federal Register.

The findings state: "Currently, however, listing the island marble butterfly is precluded by higher priority actions to amend the Lists of Endangered and Threatened Wildlife and Plants. Upon publication of this 12-month petition finding, we will add the island marble butterfly to our candidate species list. We will develop a proposed rule to list the island marble butterfly as our priorities allow."

Based on our review of the best available scientific and commercial information pertaining to the five factors, we identified the following threats:

(1) Habitat loss attributable to plant succession and competition with invasive species, herbivory by deer and European rabbits, and storm surges;

(2) direct predation by spiders and wasps, and incidental predation by deer;

(3) small population size and vulnerability to stochastic events; and

(4) the cumulative effects of small population size and restricted range combined with any other stressor that removes individuals from the population or decreases the island marble butterfly’s reproductive success.

These threats have affected the island marble butterfly throughout the entirety of its range, are ongoing, and are likely to persist into the foreseeable future. When considered individually and cumulatively, these threats are of a high magnitude. Despite existing regulatory mechanisms and other conservation efforts, the threats to the subspecies remain sufficient to put the subspecies is in danger of extinction or likely to become so in the foreseeable future. On the basis of the best scientific and commercial information available, we find that the petitioned action to list the island marble butterfly as an endangered or a threatened species is warranted.

We will make a determination on the status of the subspecies as an endangered or threatened species when we publish a proposed listing determination. However, the immediate proposal of a regulation implementing this action is precluded by higher-priority listing actions, and progress is being made to add or remove qualified species from the Lists of Endangered and Threatened Wildlife and Plants.

We reviewed the available information to determine if the existing and foreseeable threats render the subspecies at risk of extinction now such that issuing an emergency regulation temporarily listing the subspecies under section 4(b)(7) of the Act is warranted. We determined that issuing an emergency regulation temporarily listing the island marble butterfly is not warranted for this subspecies at this time because there are no imminent threats that immediate Federal protection would feasibly ameliorate.

However, if at any time we determine that issuing an emergency regulation temporarily listing the island marble butterfly is warranted, we will initiate emergency listing at that time. We assigned the island marble butterfly a listing priority number (LPN) of 3 based on our finding that the subspecies faces threats that are imminent and of high magnitude.

These threats include: (1) Habitat loss attributable to plant succession and competition with invasive species, herbivory by deer and European rabbits, and storm surges; (2) direct predation by spiders and wasps, and incidental predation by deer; (3) small population size and vulnerability to stochastic events; and (4) the cumulative effects of small population size and restricted range combined with any other stressor that removes individuals from the population or decreases the island marble butterfly’s reproductive success.

This is the highest priority that can be provided to a subspecies under our guidance. The island marble butterfly will be added to the list of candidate species upon publication of this 12-month finding. We will continue to evaluate this subspecies as new information becomes available.

Continuing review will determine if a change in status is warranted, including the need to make prompt use of emergency listing procedures. We intend that any proposed listing determination for the island marble butterfly will be as accurate as possible.

Therefore, we will continue to accept additional information and comments from all concerned governmental agencies, the scientific community, industry, or any other interested party concerning this finding.  

The complete text of the findings is available here. 

Previous articles. 

Leave a comment

Make sure you enter all the required information, indicated by an asterisk (*). HTML code is not allowed.

back to top