Emergency listing of the Miami blue butterfly
Conservation challenges, measures, and actions
Photo: © Paula Cannon
Photo: © Paula Cannon
Historic and current known range of the Miami blue butterfly (Cyclargus thomasi bethunebakeri)
Now only known to be extant in Key West NWR.
Could occur in other suitable habitat in Monroe and Miami-Dade counties or elsewhere.
Surveys continuing in remote areas and former sites by researchers, groups, and other individuals.
Photo by: Paula Halupa Bahia Honda State Park Photo by: Paula Halupa Key West NWR Photo by: Paula Halupa Key West NWR Photo by: Paula Halupa Elliott Key, BNP Photo by: Marc Minno East Cape, Cape Sable, Everglades National Park Basic life history attributes • multiple overlapping broods, occurs year-round • possible slight reproductive diapause (December to February) or delayed emergence due to cold • generation time - ~30-40 days
Adults . only live a few days . use a variety of nectar sources . nonmigratory, very sedentary . limited dispersal capabilities
Larvae . use nickerbean (Caesalpinia spp.), blackbead (Pithecellobium spp.), balloonvine (Cardiospermum spp.), Acacia spp. . tended by ants Photo: © Paula Cannon
Photo: © Paula Cannon
Photo: © Paula Cannon
Photo: © Paula Cannon
Threats (5 factor analysis)
Factor A. Present or threatened destruction, modification, or curtailment of its habitat or range
• substantial curtailment of range - >99% decline in area occupied • human population growth and development - coastal areas • habitat loss and fragmentation - extensive • detrimental land management practices (e.g., removal of hostplants, nectar sources) • climate change and sea level rise
Threats to habitat have operated in the past, are impacting subspecies now, will impact in foreseeable future.
Environmental effects from climate change expected to be severe.
Threats Factor B. Overutilization for commercial, recreational, scientific, or educational purposes
Collection • even limited collection could have deleterious effects on reproductive and genetic viability • rare butterflies prized by collectors • illegal collection of other imperiled species on Federal lands • market for similar blues and other candidate species
Scientific research and conservation efforts Considered: • mark-recapture • captive propagation and reintroduction activities • use of captive-reared butterflies in pesticide-use and life-history studies
Collection is a significant threat. [Scientific studies have potential to harm.]
Threats Factor C. Disease or predation
Disease • baculovirus - confirmed within captive colony • other disease or pathogens in the wild? (e.g., Wolbachia)
Predation • impact of native predators - unclear (e.g., wasps, orb spiders, anoles) • iguanas likely consume eggs and larvae when feeding on hostplants • impact of invasive fire ants - unclear • some ants may depredate larvae • some ants may protect larvae against parasitoids and predators; others may opportunistically tend larvae without providing protection
Stressors have potential to negatively impact; no evidence of impacts to wild population.
Disease and predation could pose threat to survival.
Threats
Factor D. Inadequacy of existing regulatory mechanisms
Considered: • FWC’s listing in 2002; State’s protective measures, management plan • occurrence on Federal, possible State, other conservation lands • limited protection afforded by being a Federal candidate
Miami blue continued to decline due to effects of habitat loss (Factor A) and a wide array of other factors (Factors B and E).
Existing regulatory mechanisms insufficient; do not offer adequate protection.
Threats
Factor E. Other natural or manmade factors affecting its continued existence
Impact from iguanas • damage to nickerbean at BHSP; damage to blackbead - unknown • widespread distribution; difficulties with control
Competition - no evidence that resource competition is a threat
Inadvertent impacts from humans • trampling of nickerbean at BHSP; local disturbances within KWNWR • damage to balloonvine along roads in Keys
Other natural and unnatural changes to habitat • succession, growth of climbing vine
Threats
Invasive and exotic vegetation - potential threat
Pesticides • use of mosquito control adulticides (naled and permethrin) • drift into unintended areas • persistence on vegetation • lethal and sub-lethal effects
Aerial and ground-based spraying have potential to deliver pesticides in quantities sufficient to cause adverse effects to non-targets in targeted and non-targeted areas.
Naled killed Miami blue larvae in field trials.
Threats
Effects of small population size and isolation • reduced range, small population size, few populations, relative isolation • population size of 1,000 - only marginally viable for an insect • <200 adults per generation - difficulty surviving over long-term
• isolation – prevents influx of new genetic material, leads to low diversity, can impact viability, and increase extinction risk
Loss of genetic diversity documented already (historical populations more diverse than contemporary populations).
No gene flow between contemporary populations.
Threats
Aspects of its natural history (lycaenids in general) • sedentary / limited dispersal – more susceptible to local extinction events • dependence on ants – may need right hostplant + right ants
Environmental stochasticity • prolonged cold temperatures (recent), hard freezes (late 1980s) • extended dry conditions, drought • tropical storms and hurricanes • climate change – increased frequency or severity of storms/weather?
Wide array of natural or manmade factors are affecting the Miami blue’s continued existence.
Threats operated in the past, are impacting the subspecies now, and will continue to impact in the foreseeable future.
Emergency listing
• We can emergency list a species if threats constitute an emergency posing a significant risk to its well-being [section 4(b)(7) of the Act and regulations under 50 CFR 424.20].
• Survival - now depends on protecting occupied and suitable habitat; restoring potential habitat within historical range; removing and reducing numerous threats; increasing population size; retaining remaining genetic diversity; and establishing populations at additional locations.
• Protections (afforded through sections 7, 9, and 10) and recognition that immediately become available increase likelihood that this butterfly can be saved from extinction and ultimately recovered.
Emergency and proposed listing rules
• Rules published in Federal Register on 8/10/11 – emergency rule provides immediate protection
• Emergency rule - lists Miami blue as Endangered and cassius, ceraunus, and nickerbean blues as Threatened due to similarity of appearance for 240 days (expires 4/6/12)
• Designation of critical habitat was determined to be not prudent (increased harm); would only provide marginal benefits
• Proposed rule – invites public comment (must be received by 10/11/11)
Proposed and final rules
• Peer review – proposed rule undergoing scientific peer review; sent to 14 independent reviewers (comments due 10/11/11)
• Extensive outreach and notification (media, Congressionals, agencies, interested parties, stakeholders; legal notices published in 5 newspapers)
• Public comments – posted to www.regulations.gov
• Will consider any new information, materials, comments received
• Final rule – may differ from proposed rule; generally expected to publish prior to expiration of emergency rule to avoid lapse in protection
Section 9
1. Unauthorized possession, trapping, capturing, killing, harrassing, sale, delivery, or movement (including commerce), or harming any life stage without a permit [some research may need 10(a)(1)(A)].
2. Incidental take w/o a permit [10(a)(1)(B)].
3. Sale or purchase of specimens, except those >100 years old.
4. Unauthorized destruction or alteration of habitat (includes destruction of occupied or potentially occupied habitat or pesticide application in known occupied habitat) in ways that kills or injures, eggs, larvae, or adults.
Section 9
5. Use of pesticides/herbicides in violation of label restrictions resulting in take of Miami blue butterfly or ants in areas occupied by the butterfly.
6. Unauthorized release of biological control agents that attack any life stage of the Miami blue or associated ants.
7. Removal or destruction of native food plants within areas used by the Miami blue that results in harm to the butterfly.
8. Release of exotic species into occupied habitat that may displace the Miami blue or its native hostplants.
ceraunus blue (Hemiargus ceraunus antibubastus) cassius blue (Leptotes cassius theonus) nickerbean blue (Cyclargus ammon) Miami blue (Cyclargus thomasi bethunebakeri)
Photos: © Paula Cannon
Similarity of Appearance
• Allowed if: (a) so closely resembles that enforcement would have substantial difficulty differentiating; (b) effect of substantial difficulty is additional threat; (c) such treatment will substantially facilitate enforcement and further protection [section 4(e)].
• Extending the prohibitions of collection, possession, and trade to the other S/A butterflies helps provide greater protection to the Miami blue.
• Special rule - prohibits take of cassius, ceraunus, or nickerbean butterflies or their immature stages throughout their ranges [section 4(d)].
• Extends take prohibitions of section 9, but does not extend other protections of the Act (e.g., sections 7, 4).
• Scientific activities of S/A butterflies allowed with prior written authorization. All otherwise legal activities conducted in accordance with State, Federal, local laws are not considered take.
Photo by: Holly L. Salvato Conservation Actions
• Wherever possible, avoid impacts to larval hostplants and adjacent nectar sources (in Monroe and Miami-Dade, also elsewhere in historical range).
• Conduct more (frequent and intense) surveys for possible presence in suitable habitat with greatest potential (especially in Monroe and Miami- Dade, but also in other areas with good potential).
• Consider restoration potential (e.g., restore / enhance habitat, remove exotics, plant larval hostplants in areas with abundant nectar sources).
• Consider establishing additional no-spray zones in suitable habitat (focus in areas with greatest potential, other areas where feasible).
• Find other ways to remove / reduce threats (e.g., set aside habitat, restore connectivity [metapopulations], retain remaining genetic diversity, adjust land management practices).
Conservation Actions
• Conduct studies to better understand life history and threats (e.g., mortality factors affecting immature stages, disease, parasitoids, ants, iguanas, genetics, metapopulation dynamics).
• Re-evaluate captive propagation (need, goals, objectives, approach). Seek input from established, successful programs.
• Refine / re-evaluate reintroduction techniques. Consider using surrogate butterflies. Employ techniques from successful efforts.
• Evaluate sites for potential reintroductions (with landowners and partners, considering suitability of habitat and extent of threats).
• Make use of mechanisms and programs (Safe Harbor Agreements and MOUs; HCPs and conservation banks; Partners and Coastal programs).
• Raise awareness, engage partners, exchange information, work together.
Questions?
Photo by: Paula Halupa Key West NWR