[Federal Register: January 3, 2002 (Volume 67, Number 2)]
[Proposed Rules]               
[Page 280-282]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]

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Fish and Wildlife Service

50 CFR Part 17

Endangered and Threatened Wildlife and Plants; 90-Day Finding for 
a Petition To List the Miami Blue Butterfly as Endangered With Critical 

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of 90-day petition finding and initiation of status 


SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 
90-day finding for a petition to list the Miami blue butterfly 
(Hemiargus thomasi bethunebakeri) under the Endangered Species Act of 
1973, as amended. The range of this butterfly, which once extended 
north along the Florida coasts to about St. Petersburg and Daytona, has 
been shrinking for many years. We find that the petition presented 
substantial information indicating that listing this species may be 
warranted. We are initiating a status review to determine if listing 
the Miami blue butterfly is warranted.

DATES: The finding announced in this document was made on December 20, 
2001. To be considered in the 12-month finding for this petition, 
information and comments should be submitted to us by March 4, 2002.

ADDRESSES: Data, information, comments, or questions concerning this 
petition should be submitted to the South Florida Ecological Services 
Office, U.S. Fish and Wildlife Service, 1339 20th Street, Vero Beach, 
Florida 32960. The petition finding, supporting data, and comments are 
available for public inspection, by appointment, during normal business 
hours at the above address.

FOR FURTHER INFORMATION CONTACT: David Martin at the above address 
(561-562-3909, extension 230).



    Section 4(b)(3)(A) of the Endangered Species Act of 1973, as 
amended (Act) (16 U.S.C. 1531 et seq.), requires that we make a finding 
on whether a petition to list, delist, or reclassify a species presents 
substantial scientific or commercial information to demonstrate that 
the petitioned action may be warranted. This finding is to be based on 
all information available to us at the time the finding is made. To the 
maximum extent practicable, we are to make this finding within 90 days 
of the date we received the petition and promptly publish it in the 
Federal Register. If the finding is that substantial information was 
presented, we are also required to promptly commence a review of the 
status of the species involved if one has not already been initiated 
under our internal candidate assessment process. After completing the 
status review, we will issue an additional finding (the 12-month 
finding) determining whether listing is in fact warranted.
    On June 15, 2000, we received a petition, dated June 13, 2000, from 
Dr. Jeffrey Glassberg, president of the North American Butterfly 
Association, Morristown, New Jersey, and Mr. Mark Salvato, an 
entomologist in St. Petersburg, Florida. The petition requested that we 
list the Miami blue butterfly as an endangered species on an emergency 
basis, and that critical habitat be designated concurrent with listing.
    The petitioners cited habitat loss as a threat to the Miami blue 
butterfly. They suggested that fragmentation of habitat is a threat to 
this butterfly because if a local population becomes extinct, surviving 
populations of Miami blues are unlikely to be nearby, and butterflies 
will not be able to disperse into the unoccupied habitat. The petition 
also suggested that vegetation management on public land (notably lack 
of prescribed fires and suppression of natural ones) is adversely 
affecting Miami blue butterflies, as it does not maintain the 
appropriate native plant species required by the butterfly. Further, 
the petition cited unethical butterfly collection as a potential threat 
to the Miami blue. Finally, the petition asserted that mosquito control 
measures (i.e., spraying of adulticides) may threaten this species.
    The Miami blue is the only subspecies of Hemiargus thomasi in the 
United States. The other subspecies are in the Bahamas, Hispaniola, and 
islands further east in the Antilles. Guides to Florida and Caribbean 
butterflies differ over whether the Miami blue also occurs in the 
Bahamas. Minno and Emmel (1993) considered it restricted to Florida, 
while Smith et al. (1994) noted that it had been recorded from the 
Bimini Islands in the Bahamas as does Calhoun (1997). Calhoun et al. 
(in press) surmise that it may not be a permanent resident in the 
Bahamas. In any case, the vast majority of this subspecies' 
distribution was in Florida, with any populations in the Bahamas being 
    Little historic information exists on the abundance of the Miami 
blue, but its distribution has clearly shrunk. Kimball (1965) stated 
that ``it is not rare in the area from Gainesville and Tampa south, and 
is common in Dade and Monroe Counties. It has been taken in the Dry 
Tortugas.'' Opler and Krizek (1984) showed its range as being from 
Tampa Bay and Cape Canaveral southward. Minno and Emmel (1993) stated 
that ``although populations of the Miami blue have declined on the 
southern mainland, it is still locally common in the Keys'' (pp. 134-
35). However, this statement was based on a 1980 reference. Calhoun et 
al. (in press) place the historic limits of the species' northern 
distribution at Hillsborough and Volusia Counties, extending southward 
along the coasts to the Marquesas Keys to the west of Key West, based 
on information from Forbes (1941) and Kimball (1965), as well as 
unpublished data assembled by Calhoun.
    The Miami blue is closely related to the nickerbean blue (Hemiargus 
ammon), a Cuban species that has recently become established on Big 
Pine Key (Calhoun et al. in press). The potential for confusing these 
two species, as well as a third, the Florida blue (Hemiargus ceraunus 
antibubastus), makes it essential to base distribution records on 
specimens or photographs rather than sightings.
    The petitioners' evidence, augmented by other available 
information, especially a paper by Calhoun et al. (in press), 
demonstrate that this subspecies has become hard to find. No 
observations of the Miami blue were supported by photographs or 
specimens from 1993 (Calhoun et al. in press) until November 1999, when 
Jane Ruffin provided a photographically verified report of about 50 
individuals at a site in southern Florida. Her report was published in 
the spring 2000 issue of American Butterflies (Ruffin and Glassberg 
2000). Calhoun et al. (in press) note an additional confirmed 
population near the one observed in 1999 as well as a credible sighting 
by R. Gillmore on Key Largo, which was posted on the North American 
Butterfly Association's website (http://www.naba.org/sightings/
sightingsMay2001Archive.htm). The petitioners cited biologists and 
others who have searched for butterflies in southern Florida in recent 
years without sighting the Miami blue. This strongly indicates that the 
Miami blue is now very restricted in its distribution and nowhere 
    Larval food plants for the Miami blue butterfly include the seed 
pods of nickerbeans (Caesalpinia spp.), which are common tropical 
coastal shrubs and vines, as well as blackbeards

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(Pithecellobium spp.) and perhaps other members of the pea family, such 
as Acacia (Calhoun et al. in press). Miami blue larvae also utilize 
balloon vine (Cardiospermum halicababum) seedpods (Opler and Krizek 
1984, Minno and Emmel 1994). These vines, belonging to the soapberry 
family, are not native to Florida, but are relatively common, 
especially in urban areas. Additionally, Calhoun et al. (in press) 
suggest that larvae of the Miami blue, like those of the nickerbean 
blue, may feed on species of Acacia that are abundant on Big Pine Key.
    The petition cites habitat loss and fragmentation as a threat. The 
Miami blue was a coastal species, known to feed on distinctly coastal 
trees and shrubs, which occur in tropical coastal hammocks (forests) 
and scrub. It also occurred in pine rocklands (slash pine with small 
palms and a grassy understory) on Big Pine Key (Calhoun et al. in 
press) and presumably in Miami-Dade County. Much of that habitat is 
gone, especially on the mainland, and what is left is fragmented. For 
example, the entire coastline in Palm Beach, Broward, and Miami-Dade 
Counties (as far south as Miami Beach) is densely urban, with only 
small remnants of coastal vegetation conserved in parks. In coastal 
areas where undeveloped land remains, the Miami blue's larval food 
plants are likely to be displaced by invasive exotic plants such as 
Brazilian pepper (Schinus terebinthifolius), which is now a dominant 
plant in coastal Florida. The seriousness of the loss and fragmentation 
of natural habitats is uncertain, partly because larvae of the Miami 
blue feed on balloon vines, which are exotic, weedy, and likely to be 
present in the urban landscape. It is possible that balloon vines could 
provide patches of suitable larval feeding habitat that would allow 
Miami blue butterflies to disperse between patches of suitable natural 
    The petition suggests that fragmentation of habitat is a threat to 
this butterfly because if a local population becomes extinct, surviving 
populations of Miami blues are unlikely to be nearby, and butterflies 
will not be able to disperse into the unoccupied habitat. Calhoun et 
al. (in press) provide indirect evidence that this may be the case on 
Big Pine Key, which appears to be unoccupied by the Miami blue, but is 
occupied by the nickerbean blue butterfly. The food plants of the two 
species seem similar enough to indicate that the Miami blue became 
extirpated from Big Pine Key in the 1990s for reasons other than loss 
of suitable habitat, and has not recolonized the island.
    The petition suggests that vegetation management on public land, 
notably lack of prescribed fires and suppression of natural ones, is 
adversely affecting butterflies. Calhoun et al. (in press) report that, 
until it disappeared from Big Pine Key in the early 1990s, the Miami 
blue most commonly occurred in pine rocklands that are now used by the 
nickerbean blue. This is a fire-dependent habitat and it is conceivable 
that the success of the Miami blue in pinelands depended on regular 
burning, although as Calhoun et al. (in press) note, host plants 
(Caesalpinia and Acacia) appear to be abundant. It did not seem to them 
that habitat loss or modification was likely to have caused the loss of 
the Miami blue from Big Pine Key.
    The petition cited unethical butterfly collection as a potential 
threat to this species. While we have listed several butterflies to, in 
part, protect them from collectors, it is not yet possible to 
demonstrate that collecting is threatening this species. However, 
unless this butterfly proves to be more widespread than is currently 
known, collection may be a threat due to the species rarity and 
apparently spotty distribution.
    Butterflies are potentially subject to intense collection 
pressures, and recent listings of butterflies as endangered or 
threatened species have been based on this threat (notably the Saint 
Francis' satyr (Neonympha mitchellii francisci), emergency-listed, 59 
FR 18324, April 15, 1994; callippe and Behren's silverspot butterflies 
(Speyeria callippe callippe and Speyeria zerene behrensii), 62 FR 
64306, December 5, 1997; and Blackburn's sphinx moth (Manduca 
blackburni), 65 FR 4770, February 1, 2000). The Saint Francis' satyr 
was demonstrated to have been hard hit by collectors in just a 3-year 
period. On the other hand, our 90-day petition finding for the Santa 
Monica Mountains hairstreak (Satyrium auretorum fumosum) (64 FR 62641, 
November 17, 1999) found that collection and other threats were not 
serious enough to warrant listing. Along with collectors interested in 
making money, butterflies also attract obsessive collectors (Alexander 
1996, Williams 1996).
    The Miami blue butterfly's apparent rarity makes it vulnerable to 
random events such as hurricanes or possibly freezes that can 
temporarily destroy the foliage of larval food plants.
    The petition asserted that mosquito control measures (i.e., 
spraying of adulticides) may threaten this species. Salvato (1999) 
studied factors influencing the declining populations of three 
butterfly species in the lower Keys. Although the species he studied 
have life histories that are different from that of the Miami blue, his 
masters thesis demonstrates that mosquito adulticide spraying can harm 
butterflies at the National Key Deer Refuge on Big Pine Key. He 
suggested specific expansions of the existing no-spray zones to protect 
the breeding grounds of these butterflies. His study is one of several 
conducted by a group of researchers on the problems of mosquito control 
pesticides in the ecosystem (Emmel 1991), which focused on conservation 
of the endangered Schaus swallowtail butterfly (Papilio aristodemus) on 
Key Largo. They found a ``probably causal'' correlation between the 
history of mosquito control on Key Largo and the decline of the Schaus 
swallowtail butterfly there.
    The petitioners stated that, due to aspects of the Miami blue's 
natural history, especially its association with ants, ``roadside 
adulticide applications may be having much larger negative impacts on 
H. t. bethunebakeri populations than on those of other lycaenid species 
in the Keys. Miami blue larvae mature in the stem and seed pods of 
their host. These larvae leave the entrance holes open so that ants can 
enter the seed pods and stems and interact with the larvae. Dr. Jenella 
Loge (University of Utah) has discovered that these ants and the Miami 
blue larvae die when spraying begins in late spring on the Keys. Larvae 
of other lycaenid species on the Keys, ones without mutualistic 
relationships with ants, plug the holes of their seed pods and stems to 
keep would-be predators outside, and this may also restrict the 
entrance of adulticide spray.'' About half of the world's lycaenid 
butterfly species associate with ants. Cushman and Murphy (1993) 
suggest that ant-dependent lycaenid butterflies are inherently more 
vulnerable to extinction than those that are not ant-dependent because 
of the consequences of needing both the right food plants and the right 
ants, simultaneously. Based on information from Calhoun et al. (in 
press) and Salvato (1999), mosquito spraying appears likely to have 
contributed to the decline of the Miami blue and might be inhibiting 
recolonization of suitable habitats.
    We have reviewed the petition, the literature cited in the 
petition, and other literature and information available in our files. 
On the basis of the best scientific and commercial information, we find 
the petition presents substantial information that listing this species 
may be warranted. Habitats that were probably formerly occupied by the 
Miami blue butterfly have been

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destroyed or fragmented. The available information suggests that the 
Miami blue is rare and may exist only in small numbers at a few sites. 
This probable rarity suggests that the species might not be able to 
recolonize former portions of its range that may have suitable, but 
unoccupied, habitat. Also, the available information demonstrates that 
mosquito spraying in the Florida Keys and probably other parts of the 
Miami blue's former range has the potential to harm this species.
    The petitioners stated that the Miami blue butterfly's last known 
population may be destroyed by mosquito control adulticide treatments, 
by human-caused changes to its habitat on the public land it inhabits, 
or by unethical butterfly collectors, and they requested emergency 
listing of the species. We may issue an emergency rule when an 
immediate threat poses a significant risk to the well-being of a 
species. Although the Miami blue butterfly appears to be in danger of 
extirpation, we do not believe that the threats are so great that 
extirpation is imminent. Upon receiving the petition, we reviewed the 
available information to determine if the existing and foreseeable 
threats posed an emergency. Consequently, we determined that an 
emergency listing was not warranted at this time. However, if at any 
time we determine that emergency listing of the Miami blue butterfly is 
warranted, we would seek to initiate an emergency listing. The 
petitioners also requested that critical habitat be designated for this 
species. We always consider the need for critical habitat designation 
when listing species. If the 12-month finding determines that listing 
the Miami blue butterfly is warranted, then the designation of critical 
habitat will be addressed in the subsequent proposed rule.

Public Information Solicited

    When we make a finding that substantial information exists to 
indicate that listing a species may be warranted, we are required to 
promptly commence a review of the status of the species. To ensure that 
the status review is complete and based on the best available 
scientific and commercial information, we are soliciting information on 
the Miami blue butterfly. We request any additional information, 
comments, and suggestions from the public, other concerned governmental 
agencies, the scientific community, industry, or any other interested 
parties concerning the status of the Miami blue butterfly. We are 
seeking information regarding historic and current distribution, 
habitat use and habitat conditions, biology and ecology, ongoing 
conservation measures for the species and its habitat, and threats to 
the species and its habitat.
    If you wish to comment, you may submit your comments and materials 
concerning this finding to the Supervisor, South Florida Ecological 
Services Office, U.S. Fish and Wildlife Service, 1339 20th Street, Vero 
Beach, Florida 32960. Our practice is to make comments, including names 
and home addresses of respondents, available for public review during 
regular business hours. Respondents may request that we withhold their 
home address, which we will honor to the extent allowable by law. There 
also may be circumstances in which we would withhold a respondent's 
identity, as allowable by law. If you wish us to withhold your name or 
address, you must state this request prominently at the beginning of 
your comment. However, we will not consider anonymous comments. To the 
extent consistent with applicable law, we will make all submissions 
from organizations or businesses, and from individuals identifying 
themselves as representatives or officials of organizations or 
businesses, available for public inspection in their entirety. Comments 
and materials received will be available for public inspection, by 
appointment, during normal business hours at the above address.

References Cited

    You may request a list of all references cited in this document, as 
well as others, from the South Florida Ecological Services Office (see 
ADDRESSES section).


    The primary author of this document is David Martin, South Florida 
Ecological Services Office (see ADDRESSES section).


    The authority for this action is the Endangered Species Act (16 
U.S.C. 1531 et seq.).

    Dated: December 20, 2001.
Marshall P. Jones Jr.,
Director, Fish and Wildlife Service.
[FR Doc. 02-36 Filed 1-2-02; 8:45 am]