[Federal Register Volume 59, Number 149 (Thursday, August 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-18932]
[[Page Unknown]]
[Federal Register: August 4, 1994]
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Part III
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Species: Cuyamaca Lake Downingia; San Diego
Fairy Shrimp; Laguna Mountains Skipper, et al.; Proposed Rules
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AC84
Endangered and Threatened Wildlife and Plants; Proposed Rule To
List the Laguna Mountains Skipper and Quino Checkerspot Butterflies as
Endangered
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule and petition findings.
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SUMMARY: The Fish and Wildlife Service (Service) proposes to list the
Laguna Mountains skipper (Pyrgus ruralis lagunae) and quino checkerspot
(Euphydryas editha quino) butterflies as endangered species throughout
their respective ranges in southwestern California and northwestern
Baja California, Mexico pursuant to the Endangered Species Act of 1973,
as amended (Act). The Laguna Mountains skipper occupies two montane
meadow habitats in a very restricted range within San Diego County,
California. The quino checkerspot is locally distributed in sunny
openings within chaparral and coastal sage shrublands in portions of
Riverside County, California and northwestern Baja California, Mexico.
These species are threatened by one or more of the following factors:
Grazing, urban development, collection by lepidopterists and other
human disturbance, stochastic events, and the inadequacy of existing
regulatory mechanisms to provide for their conservation. This proposed
rule, if made final, would extend protection under the Act to these
species.
DATES: Comments from all interested parties must be received by October
3, 1994. Public hearing requests must be received by September 19,
1994.
ADDRESSES: Comments and materials concerning this proposal should be
sent to the Field Supervisor, U.S. Fish and Wildlife Service, Carlsbad
Field Office, 2730 Loker Avenue West, Carlsbad, California 92008.
Comments and materials received will be available for public
inspection, by appointment, during normal business hours at the above
address.
FOR FURTHER INFORMATION CONTACT: Ms. Marjorie Nelson at the above
address (telephone 619/431-9440).
SUPPLEMENTARY INFORMATION:
Background
The Laguna Mountains skipper (Pyrgus ruralis lagunae) is a small
butterfly within the skipper family (Hesperiidae). It is about 3
centimeters (cm) (1 inch) in length and is distinguished from the rural
skipper (P. ruralis ruralis) by extensive white wing markings that give
it an overall appearance of white rather than mostly black (Scott
1981). The Laguna Mountains skipper is found in wet montane meadow
habitats.
Pyrgus ruralis lagunae is one of two recognized subspecies of the
rural skipper, Pyrgus ruralis (Boisduval). Scott (1981) first described
Pyrgus ruralis lagunae from a collection made in 1956 by F. Thorne in
the Laguna Mountains of San Diego County California, based upon
population isolation and color differentiation. The Laguna Mountains
skipper is restricted to the Laguna Mountains and Mount Palomar in San
Diego County.
The other subspecies of the rural skipper (Pyrgus ruralis ruralis)
ranges from the mountains of British Columbia and Alberta south to
central California, Nevada, Utah, and northern Colorado (J. Brown,
Dudek and Associates, in litt., 1992) and has darker wings than the
Laguna Mountains skipper.
Three other species in the genus Pyrgus occur in San Diego County:
the common checkered skipper (P. communis); the small checkered skipper
(P. scriptura); and the western checkered skipper (P. albescens). The
Laguna Mountains skipper can be distinguished from all three of these
species by the whitish appearance of the adults and the use of a single
larval host plant in the rose family (Horkelia clevelandi) (Garth and
Tilden 1986, Scott 1986). In addition, the western checkered skipper
and southern California populations of the small checkered skipper are
restricted to desert areas (Garth and Tilden 1986).
The Laguna Mountains skipper is currently found at one site in the
Laguna Mountains and one site on Mount Palomar in San Diego County,
California (Dr. John Brown, in litt., 1992). The total population of
the Laguna Mountains skipper is estimated to be fewer than 100
individuals (Murphy 1990; Brown 1991; J. Brown, in litt., 1992). The
Laguna Mountains population is restricted to a relatively small fenced
area where cattle cannot reach the larval host plant (G. Pratt, as
cited in Murphy 1990; Dave Hogan, San Diego Biodiversity Project, pers.
comm., 1993). The Laguna Mountains skipper was sighted and collected on
Mount Palomar in 1991 by D. Lindsley (J. Brown, in litt., 1992; Dr.
John Brown, pers. comm., 1993). The Mount Palomar population is
extremely small where only five specimens have been reported in this
century (J. Brown, in litt., 1992).
Horkelia clevelandi (Cleveland's horkelia) is the larval host plant
of the Laguna Mountains skipper. Cleveland's horkelia occurs along the
margins of pine meadows in the Laguna, Cuyamaca, Palomar, and San
Jacinto Mountains of southwestern California and northwestern Baja
California, Mexico at 1200 to 2500 meters (m) (4000 to 8000 feet) in
elevation. Although a butterfly's distribution is generally defined by
the presence of its larval host plant, it may be further restricted by
other physiological or ecological constraints. The Laguna Mountains
skipper is currently found in a few open meadows of yellow pine forest
between 1500 to 2000 m (5000 and 6000 feet) in elevation; historically,
this species was found at elevations between 1200 and 2500 m (4000 to
6000 feet). It may have occurred throughout the higher elevations of
San Diego County (Murphy 1990; Brown 1991; J. Brown, in litt., 1992;
and references cited therein). Murphy (1990) reported that there were
at least six populations of this species in the Laguna Mountains in the
1950's and 1960's (at Big Laguna, Little Laguna, East Laguna, Laguna
Lake, Boiling Springs, and Horse Heaven) (see also J. Brown, in litt.,
1992). Most specimens of the Laguna Mountains skipper were collected
from Horse Heaven Springs near Mount Laguna (Murphy 1990). Until
rediscovery in 1983 by J. Emmel, the last known sightings of the
skipper in the Laguna Mountains were from 1972. Until specimens were
collected in 1991, the last known sightings from Mount Palomar were
from 1980 and, prior to that, from 1939 (Brown 1991; J. Brown, in
litt., 1992).
The Laguna Mountains skipper is apparently bivoltine (two
generations per year). The adult flight season occurs from April to May
with a complete or partial second brood flight in late June to late
July. A partial second brood indicates that this butterfly may have a
flexible or variable diapause (state of suspended activity). The Laguna
Mountains skipper may have evolved a unique mechanism for coping with
the low diurnal temperatures it encounters during its spring flight,
which is unusually early for butterflies in the Laguna Mountains (Brown
1991). It is assumed that the life history of the Laguna Mountains
skipper is similar to that of the nominate subspecies (Pyrgus ruralis
ruralis), which diapauses as a full grown larvae and adults live 10 to
20 days (J. Brown, in litt., 1992).
The quino checkerspot, Euphydryas (= Occidryas) editha quino (Behr)
is a small member of the brush-footed butterfly family (Nymphalidae).
It is about 3 cm (1 inch) in length and checkered with dark brown,
reddish, and yellowish spots. It is one of 12 recognized subspecies of
Euphydryas editha (editha checkerspot) (Garth and Tilden 1986). The
quino checkerspot can be distinguished from other subspecies of
Euphydryas editha by its wing coloration pattern and overall body size.
The quino checkerspot tends to be larger with redder wings. The light
spots on the wings tend to be fewer and more disjunct than in the other
subspecies (Garth and Tilden 1986). Euphydryas editha quino is
geographically disjunct from them. This taxon is also phenotypically
similar to two other species of butterfly that occur within its range.
The Chalcedon checkerspot (E. chalcedona) is more yellow and is
slightly larger than the quino checkerspot. Gabb's checkerspot
(Chlosyne gabbii) is smaller than the quino checkerspot and has orange
instead of red markings (Orsak 1977).
The quino checkerspot was first described in 1863 by Hans Herman
Behr, an entomologist with the California Academy of Sciences in San
Francisco, as Melitaea quino based on a specimen from coastal San Diego
County, California. It was subsequently recognized by Comstock (1927)
as a race of Euphydryas editha (Boisduval). For many years, E. e. quino
was inappropriately recognized as E. e. wrightii. This error was
rectified by J. Emmel based on a study of Behr's notes and available
specimens (D. Murphy, Center for Conservation Biology, Stanford
University, in litt., 1988; Allen 1990). The genus Euphydryas, which is
widely represented throughout North America, has been subdivided into
closely related species groups (Scott 1986). The genus Euphydryas is
also referred to as Occidryas, but many authors retain the former name
(e.g., Scott 1986; Harrison et al 1988; Murphy 1990; Brown 1991).
The quino checkerspot is restricted to sunny openings on clay soils
formed from gabbro parent materials within shrubland habitats of the
interior foothills of southwestern California and northwestern Baja
California, Mexico (G. Ballmer, in litt., 1991). Similar to the Laguna
Mountains skipper and butterflies in general, its distribution is
defined primarily by that of its larval host plant but is further
restricted by other factors. The primary larval food plant of the quino
checkerspot is Plantago erecta (dwarf plantain, family Plantaginaceae).
However, the larvae may also use Plantago insularis and Orthocarpus
purpurescens (owl's clover, family Scrophulariaceae) (White 1974; Greg
Ballmer, University of California at Riverside, pers. comm., 1993).
These plants grow in or near meadows, vernal pools, and lake margins in
upland shrub communities including sparse chaparral, and chaparral
mixed with coastal sage scrub. This butterfly is generally found at
sites where high densities of the host plant occur (J. Johnson, in
litt., 1989; D. Hawks, University of California at Riverside, in litt.,
1992) and was found at a variety of elevations from about sea level to
about 1200 m (4000 feet). Within these areas, the quino checkerspot may
be preferentially selecting sites where exposure to winter sun is
greatest (Allen 1990). These habitats, like the quino checkerspot
butterfly, were once commonly found along coastal bluffs, mesas, and
inland foothills (Brown and Faulkner 1984).
The quino checkerspot may have been one of the most abundant
butterflies in San Diego, Orange, and western Riverside Counties during
the early part of the 20th century (Murphy 1990). The original range of
the quino checkerspot extended as far south as Valle de la Trinidad in
northwestern Baja California, Mexico, and as far north as Point Dume in
Los Angeles County (Allen 1990). Currently, only six to seven small
populations are known within the United States. Five to six populations
occur near Vail Lake in southwestern Riverside and north-central San
Diego Counties (G. Ballmer, in litt., 1990 and 1991; David Hawks,
entomologist, University of California at Riverside, pers. comm.,
1993). One other population is known to occur (as of 1991) near Upper
Otay Lake in San Diego County (Murphy, in litt., 1991). Although the
latter population has likely been extirpated (Murphy, pers. comm.,
1994). At least one population exists in Mexico, in the Sierra Juarez
near Tecate (Murphy, in litt., 1991). Adult quino checkerspot
butterflies were not seen at several historically occupied sites in
Mexico during a survey in the spring of 1993 (unpubl. Service data). No
estimates of population size for the quino checkerspot are currently
available.
Adult quino checkerspot butterflies live from 4 to 8 weeks. The
flight season occurs from mid-January to late April, and peaks between
March and April. The eggs hatch in about 10 days, and the larvae begin
to feed immediately. Fourth instar (development stage) larvae enter an
obligatory diapause, as summer approaches and their larval food plant
senesces. Extended periods of diapause may occur during times of
drought (G. Ballmer, in litt., 1990). Post-diapause larvae develop
through four more instars and then pupate to emerge as adults in the
early spring (Murphy and White 1984).
Previous Federal Action
On June 3, 1991, the Service received a petition dated May 27,
1991, from Mr. David Hogan of the San Diego Biodiversity Project, to
list four butterfly species as endangered under the Endangered Species
Act of 1973, as amended (16 U.S.C. 1531 et seq.): the Laguna Mountains
skipper (Pyrgus ruralis lagunae), Hermes copper (Lycaena hermes),
Thorne's hairstreak (Mitoura thornei), and Harbison's dun skipper
(Euphyes vestris harbisoni). The petition cited loss and degradation of
habitat, through various causes, as the major threat to these
butterflies. On July 12, 1993, the Service found that the petition
contained substantial information indicating that the requested action
may be warranted for the Laguna Mountains skipper, but not for the
other three butterflies listed above. The latter finding was made
because sufficient information was not available regarding the threats
to and biological vulnerability of these taxa. An announcement of these
findings were published in the Federal Register on July 19, 1993 (58 FR
38549). The Laguna Mountains skipper, Hermes copper, Thorne's
hairstreak, and Harbison's dun skipper are currently classified as
category 2 candidates for Federal listing (November 21, 1991; 56 FR
58804). Category 2 includes taxa for which information in the Service's
possession indicates that listing is possibly appropriate but for which
the Service lacks substantial information upon which to base a proposal
to list as endangered or threatened.
On September 30, 1988, the Service received a petition dated
September 26, 1988, from Dr. Dennis Murphy of the Stanford University
Center for Conservation Biology, to list the quino checkerspot
butterfly (Euphydryas editha quino) as endangered under the Act. At the
time this petition was submitted, this taxon had not been seen for
several years and was thought to be extinct. Extant populations of the
quino checkerspot were reported by Dr. Murphy in a letter dated August
1, 1991, which again requested the Service to consider the petitioned
action. The status of the quino checkerspot has been under review by
the Service since 1984 when it was classified as a category 2 candidate
for Federal Listing (May 22, 1984; 50 FR 37958). This taxon is
currently classified as a category 1 candidate (November 21, 1991; 56
FR 58804), meaning that information in the Service's possession is
sufficient to support a proposal to list as endangered or threatened.
This proposed rule constitutes the final finding for the petitioned
action to list the Laguna Mountains skipper as warranted. In addition,
this proposed rule constitutes the 90-day finding that the petition for
the quino checkerspot butterfly presented substantial information that
the action may be warranted and the final 12-month finding for this
petition that the action is warranted.
Summary of Factors Affecting the Species
Section 4 of the Endangered Species Act (16 U.S.C. 1533) and
regulations (50 CFR part 424) promulgated to implement the Act set
forth criteria and procedures for adding species to the Federal Lists.
A species may be listed due to any one or a combination of the five
factors listed in section 4(a)(1) of the Act. These factors and their
application to the Laguna Mountains skipper (Pyrgus ruralis lagunae)
and the quino checkerspot (Euphydryas editha quino) are as follows.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
The habitats and the ranges of the two species considered herein
have been substantially reduced by urban and agricultural development
and recreational activities and are further threatened with
destruction, modification, and curtailment. The Laguna Mountains
skipper and the quino checkerspot currently occur within very
restricted ranges and are extremely localized in their present
distributions.
The habitat requirements for these two butterflies are primarily
defined by their larval host plants. The removal or degradation of
these plants, as well as that of nectar sources for adults, leads to
the elimination of the affected population.
In the case of the Laguna Mountains skipper, habitat destruction
and degradation from overgrazing and trampling of its larval host plant
by domestic cattle is considered to be the primary factor responsible
for its decline (Murphy 1990; D. Hogan, in litt., 1991; J. Brown, in
litt., 1992). The larval host plant (Cleveland's horkelia) is itself a
rare species and only found in the Laguna, Cuyamaca, and San Jacinto
Mountains of southwestern California, and northwestern Baja California,
Mexico. The only known extant skipper population in the Laguna
Mountains is found in the El Prado campground area of the Cleveland
National Forest (Murphy 1990; D. Hogan, pers. comm., 1993). This area
is protected from grazing cattle by a fence. Although the larval host
plant is found throughout the campground, it is subject to trampling by
people (D. Hogan, pers. comm., 1993).
Sunny openings within chaparral and coastal sage scrub occupied by
the quino checkerspot butterfly have been degraded by grazing and (to a
small degree) destroyed by urban development. Fifty to seventy-five
percent of the known range of the quino checkerspot has been lost since
1900 due to habitat degradation or destruction (Brown 1991). The
primary larval food plant, Plantago erecta, can be displaced by exotic
plants, which invade once the ground is disturbed by discing, grading,
and/or grazing (J. Johnson, in litt., 1989; G. Ballmer, in litt.,
1990). The food plant then recolonizes in sites where grass does not
grow well, like cattle trails and road edges, where quino checkerspot
larvae are subject to trampling (D. Hawks, pers. comm., 1993).
The encroachment of urban development in rural Riverside County
potentially threatens one of the quino checkerspot populations near
Vail Lake. This area is growing rapidly and is projected to be fully
developed within the decade (Monroe et al. 1992). The Vail Lake area is
included in a Community Plan that provides for subdivision of parcels
into 20-acre (9 hectare (ha)) lots (M. Freitas, in litt., 1993).
Additional development in this area is expected to further reduce and
degrade habitat of the quino checkerspot through construction of homes
and roads, and increases in cattle and horse grazing, fire frequencies,
and the distribution and abundance of exotic plants. An existing
recreational vehicle park and marina at Vail Lake attracts unauthorized
use of all terrain vehicles (ATV's) within natural habitat areas. ATV's
increase the fire hazard and destroy habitat through creation of
trails. Evidence of ATV use is apparent at one of the quino checkerspot
localities near Vail Lake, where a recently created dirt road bisects
the center of the habitat (G. Ballmer, in litt., 1991). Quino
checkerspot habitat at this locality has been disced in part; these
disturbed areas no longer support this species, while the surrounding
undisturbed areas do (G. Ballmer, in litt., 1991).
Bureau of Land Management-administered lands and Forest Service
Wilderness Areas are currently contiguous with privately-owned quino
checkerspot habitat near Vail Lake. As Riverside County becomes more
densely populated, fragmentation and degradation of this contiguous
habitat is expected.
Any residual individuals remaining near the last known population
of the quino checkerspot in San Diego County would be threatened by a
proposed urban development project on Otay Mesa. The preferred
alternative for the Otay Ranch New Town Plan (the largest planned
community in the southwestern United States) would result in the loss
of 5,600 ha (14,000 acres) of upland shrub communities, or about 52
percent of their extent within the project area. The effects of this
project on the quino checkerspot are not known at this time but may be
significant. Habitat loss due to grazing and clay mining are the
primary threats to the quino checkerspot butterfly in Mexico.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Overcollection is a potential threat to both the Laguna Mountains
skipper and the quino checkerspot because they are rare butterflies.
Johnson (in litt., 1989) has noted that the number of quino checkerspot
colonies has been reduced since lepidopterists, eager to include rare
species in their collections and to obtain surplus specimens for
exchange or sale to other lepidopterists, have visited the few
remaining colonies steadily throughout the flight season. ``Where the
populations may already be small, this depredation by collectors may so
weaken the colonies as to end their existence. I have witnessed
examples of this with other species of Lepidoptera whose loss of
habitat has restricted the species to isolated colonies. These have
then been wiped out by intensive collection by lepidopterists.'' (J.
Johnson, in litt., 1989). The remaining populations of the quino
checkerspot butterfly near Vail Lake are threatened by overcollection.
In the spring of 1993, these populations were the subject of scientific
collections for voucher specimens and captive-rearing (D. Hawks, pers.
comm., 1993). In addition, at least two collections of about six
specimens each have been made by private collectors for non-scientific
purposes (unpubl. Service data).
A significant threat to the survival of both species considered
herein is the potential for vandalism by landowners who may view the
presence of sensitive species as an obstacle to development. The
habitat of the largest and most dense quino checkerspot population in
the Gavilan Hills of Riverside County was deliberately disced, in 1984
or 1985, to eliminate this population (J. Johnson, in litt., 1989).
C. Disease or Predation
Disease is not known to be a factor affecting the species
considered herein. There are no known predators of the Laguna Mountains
skipper. However, there is evidence that predation is a threat to the
quino checkerspot. Studies conducted by David Hawks (pers. comm., 1993)
indicate that predation has contributed to the decline of the quino
checkerspot at sites where habitat has been invaded by non-native plant
species, which may also harbor predatory arthropods. Historical quino
checkerspot habitat sites that have been heavily invaded by
Mediterranean plant species also have high sowbug (Oniscus sp.) and
earwig (Forficula sp.) densities. Sowbugs and earwigs prey upon
butterfly eggs. These predators, as well as the non-native plant
species that support them, are absent from natural sites currently
occupied by the quino checkerspot butterfly (D. Hawks, pers. comm.,
1993).
Although specific parasites are unknown for the Laguna Mountains
skipper and the quino checkerspot, Johnson (in litt., 1989) speculates
that parasitism can eliminate a butterfly colony. ``* * * butterfly or
moth populations will build up on the food plants for three or four
years, then one will begin to find examples of larvae or pupae with
parasites. The parasitism increases for two or three seasons, when
nearly all of the larvae or pupae are affected, the moth or butterfly
population disappears completely from the observed area, remains absent
for some years, then the cycle is repeated'' (J. Johnson, in litt.,
1989). This cycle can only continue if the affected area is
recolonized, which is difficult when the host-butterfly population is
small, fragmented, and isolated. In general, however, outbreaks of
disease or parasitism are more likely to occur under conditions of high
population densities. The Laguna Mountains skipper occurs in low
population densities; most populations of the Quino checkerspot also
occur at low densities.
D. The Inadequacy of Existing Regulatory Mechanisms
Existing regulatory mechanisms that could provide some protection
for both the Laguna Mountains skipper and the quino checkerspot
include: (1) Listing under the California Endangered Species Act; (2)
adequate consideration under the California Environmental Quality Act
(CEQA) and the National Environmental Policy Act (NEPA); (3) local laws
and regulations; (4) occurrence with other species protected by the
Federal Endangered Species Act; and (5) land acquisition and management
by Federal, State, or local agencies, or by private groups and
organizations for the conservation of these species.
Neither of the species discussed herein is under consideration for
listing under the California Endangered Species Act.
The status of and threats to the Laguna Mountains skipper and the
quino checkerspot, as discussed under Factor A above, reflect the
failure of CEQA, NEPA, and local laws and regulations to protect and
provide for the conservation of these species. Although there are
several regional conservation planning efforts underway within the
range of the Laguna Mountains skipper and the quino checkerspot, none
have been completed, approved, funded, or implemented.
The Service is not aware of any overlap in distribution between the
Laguna Mountains skipper and any State or Federally listed species. At
some localities, the quino checkerspot co-occurs with the coastal
California gnatcatcher (Polioptila californica californica), a
Federally listed threatened species. However, the habitat requirements
for the quino checkerspot are different than for the gnatcatcher.
Some protection is afforded to the Laguna Mountains skipper on
Forest Service land. However, this protection is limited to a
campground area that is subject to human disturbance. Considering the
small population size and extremely limited distribution of the Laguna
Mountains skipper, this protection is insufficient to conserve the
species. In the case of the quino checkerspot, some protection may be
provided to one population by its occurrence, in part, on Bureau of
Land Management land near Vail Lake in Riverside County. However, this
Federal land is currently subject to off-road vehicle activity (G.
Ballmer, in litt., 1991).
The Service is not aware of any regulatory mechanisms that protect
the quino checkerspot in Mexico.
E. Other Natural or Man-Made Factors Affecting Its Continued Existence
The extremely restricted range and localized distribution, and
small population size of the Laguna Mountains skipper and the quino
checkerspot makes them vulnerable to the effects of fragmentation,
especially with regard to stochastic events (e.g., see Gilpin and Soule
1986). For example, the Mount Palomar population of the Laguna
Mountains skipper is known from one site, where five specimens were
taken. A chance event could easily extirpate this population of the
skipper.
Although both butterflies occur in fire adapted ecosystems, a
single fire event could eliminate affected populations. Orsak (1977)
reported that a quino checkerspot population near Hidden Ranch, Black
Star Canyon, in the Santa Ana Mountains of Orange County was apparently
destroyed by a fire in 1967. (As discussed in the Background section
above, the quino checkerspot is now extirpated from Orange County.) The
only site known to be occupied by the Laguna Mountains skipper in the
Laguna Mountains is subject to cattle grazing and trampling by both
cattle and people.
Interconnected populations can act as reservoirs to maintain
populations that may be subject to periodic extirpation (Murphy and
White 1984, Harrison et. al 1988). If a stochastic event eliminates a
population of either species (due to factors discussed in this rule),
few (if any) neighboring populations are available to recolonize the
area. No information is available regarding the vagility of the Laguna
Mountains skipper. The sedentary behavior of the quino checkerspot
diminishes the probability that natural, long distance dispersal could
reestablish most extirpated local populations.
Periodic droughts (like those recently occurring in southwestern
California) can adversely affect both of the species considered herein.
Drought is known to decrease numbers of butterflies (Thorne 1963).
Drought conditions may cause loss or early senescence of the larval
host plant prior to completion of larval development, or lower the
nutritional quality of the host plant (e.g., water content). Drought
can also reduce the quantity and quality of adult nectar sources.
Larval starvation and extirpation of local populations during periods
of drought have been documented for Euphydryas editha (White 1974,
Ehrlich et al. 1980).
Habitat fragmentation can affect the genetic heterogeneity of small
isolated populations like those of the Laguna Mountains skipper and the
quino checkerspot. Small, fragmented populations are subject to a
higher frequency of genetic drift and inbreeding. As a consequence,
genetic variation of the population and individual heterozygosity is
decreased. That can lead to inbreeding depression and lowered fitness
of individuals. Low genetic diversity may decrease the ability of a
species to adapt to changing environmental conditions. Genetically
homogenous populations may be at a greater risk of extinction from
environmental or demographic stochasticity (e.g., from fire or drought
events) than are large, diverse populations that can more readily
recover from such events. For example, variation in the length of
diapause among butterfly offspring requires genetic heterogeneity (see
Seger and Brockman 1987). If a population is variable in diapause
length, it has a lower risk of losing an entire cohort to adverse
environmental conditions during any given season. Individuals with
prolonged diapause may survive if drought causes high mortality during
the next season. A large population or metapopulation can maintain the
genetic heterogeneity needed to maintain the population during these
kinds of events.
The quino checkerspot is somewhat adapted to unpredictable weather
patterns but requires sufficient patches of suitable habitat to respond
to this environmental stochasticity. The quino checkerspot's dispersal
capabilities vary considerably depending upon rainfall patterns and the
resulting availability of adult nectar sources and larval food plants.
For example, a San Diego County population of the quino checkerspot
exhibited an increase in numbers as a result of favorable weather
(Murphy and White 1984). The greater number of larvae defoliated the
larval food plants. This central core area was left without sufficient
egg-laying sites for females, and adults went for greater dispersal
distances in search of additional suitable habitat. Ideally these
dispersing adults would have found marginally suitable areas, and in
subsequent generations would have returned to a central core area. In
this case, the mass dispersal failed to restore populations in
previously occupied habitat, and the butterflies have not re-colonized
the original site (Murphy and White 1984; Murphy, pers. comm. 1994).
The Service has carefully assessed the best scientific and
commercial information available regarding the past, present, and
future threats faced by these two taxa in determining to propose this
rule. Based on this evaluation, the Service finds that the preferred
action is to list the Laguna Mountains skipper and the quino
checkerspot as endangered. The range and habitat of these species has
been substantially reduced by historical activities associated with
urban and agricultural development and recreational activities. These
two taxa are threatened by one or more of the following factors:
Habitat alteration and destruction resulting from urban and
agricultural development, grazing, overcollection, recreational
activities, inadequate regulatory mechanisms, and displacement of the
larval host plant by exotic species. The extremely restricted range,
localized distribution, and small population size of both butterflies
makes them very vulnerable to extinction by the factors listed above as
well as by stochastic events such as fire and drought. For these
reasons, the Service finds that the Laguna Mountains skipper and the
quino checkerspot are in imminent danger of extinction throughout all
or a significant portion of their ranges. Threatened status would not
accurately reflect the diminished status and threats to these species.
Other alternatives to this action were considered but not preferred
because not listing these species would not provide adequate protection
and would be inconsistent with the purposes of the Act. Critical
habitat is not being proposed for these taxa for the reasons discussed
below.
Critical Habitat
Critical habitat, as defined by section 3(5)(A) of the Act, means:
(i) The specific areas within the geographical area occupied by a
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features (I) essential to the
conservation of the species and (II) that may require special
management considerations or protection; and (ii) specific areas
outside the geographical area occupied by a species at the time it is
listed, upon a determination that such areas are essential for the
conservation of the species.
Section 4(a)(3) of the Act requires that critical habitat be
designated to the maximum extent prudent and determinable concurrently
with the determination that a species is endangered or threatened. The
Service's regulations (50 CFR 424.12(a)(1)) state that designation of
critical habitat is not prudent when one or both of the following
situations exist: (1) The species is threatened by taking or other
human activity, and identification of critical habitat can be expected
to increase the degree of such threat to the species; or (2) such
designation of critical habitat would not be beneficial to the species.
The Service finds that designation of critical habitat is not
prudent at this time for the Laguna Mountains skipper and the quino
checkerspot. The quino checkerspot, mostly occurs on privately owned
lands with little or no Federal involvement, although the Bureau of
Land Management owns a portion of one site. The additional protection
provided by the designation of critical habitat to a species is only
achieved through section 7. Therefore, the designation of critical
habitat would not appreciably benefit the quino checkerspot.
Publication of precise maps and descriptions of critical habitat for
the quino checkerspot and the Laguna Mountains skipper could result in
additional habitat destruction through trampling, discing, and grading
as well as collection. As discussed under Factor B in the ``Summary of
Factors Affecting the Species'' section of this proposal, habitat for
the one of the largest quino checkerspot colonies was graded in
Riverside County to deliberately eliminate that population, and a
number of quino checkerspot colonies have been subject to collection by
lepidopterists for trading and similar purposes.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened under the Endangered Species Act include recognition,
recovery actions, requirements for Federal protection, and prohibitions
against certain practices. Recognition through listing encourages and
results in conservation actions by Federal, State, and private
agencies, groups, and individuals. The Endangered Species Act provides
for possible land acquisition and cooperation with the States and
requires that recovery actions be carried out for all listed species.
The protection required of Federal agencies and the prohibitions
against taking and harm are discussed, in part, below.
Section 7(a) of the Act, as amended, requires Federal agencies to
evaluate their actions with respect to any species that is proposed or
listed as endangered or threatened and with respect to its critical
habitat, if any is being designated. Regulations implementing this
interagency cooperation provision of the Act are codified at 50 CFR
part 402. Section 7(a)(4) requires Federal agencies to confer with the
Service on any action that is likely to jeopardize the continued
existence of a proposed species or result in destruction or adverse
modification of proposed critical habitat. If a species is subsequently
listed, section 7(a)(2) requires Federal agencies to insure that
activities they authorize, fund, or carry out are not likely to
jeopardize the continued existence of such a species or destroy or
adversely modify its critical habitat. If a Federal action may affect a
listed species or its critical habitat, the responsible Federal agency
must enter into formal consultation with the Service.
Federal agencies expected to have involvement with the Laguna
Mountains skipper and the quino checkerspot include the Forest Service
and Bureau of Land Management due to the presence of habitat and
populations within their jurisdiction. The Immigration and
Naturalization Service may need to evaluate the effects of its
activities on the quino checkerspot, which is known to occur near the
international border in San Diego County.
The Act and its implementing regulations found at 50 CFR 17.21 set
forth a series of general prohibitions and exceptions that apply to all
endangered wildlife. These prohibitions, in part, make it illegal for
any person subject to the jurisdiction of the United States to take
(including harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, collect, or to attempt any of these), import or export,
transport in interstate or foreign commerce in the course of commercial
activity, or sell or offer for sale in interstate or foreign commerce
any listed species. It is also illegal to possess, sell, deliver,
carry, transport, or ship any such wildlife that has been taken
illegally. Certain exceptions apply to agents of the Service and State
conservation agencies.
Permits may be issued to carry out otherwise prohibited activities
involving endangered wildlife species under certain circumstances.
Regulations governing such permits are at 50 CFR 17.22 and 17.23. Such
permits are available for scientific purposes, to enhance the
propagation or survival of the species, and/or for incidental take in
connection with otherwise lawful activities. In some instances
involving trade, permits may be issued for a specified time to relieve
undue economic hardship that would be suffered if such relief were not
available. The Laguna Mountains skipper and quino checkerspot are not
involved in trade, and such permit requests are not expected.
Requests for copies of the regulations on listed wildlife and
plants and inquiries regarding them should be addressed to the U.S.
Fish and Wildlife Service, Ecological Services--Endangered Species
Permits, 911 Northeast 11th Ave, Portland, Oregon 97232-4181 (telephone
503/231-6241).
Public Comments Solicited
The Service intends that any final action resulting from this
proposal will be as accurate and as effective as possible. Therefore,
comments or suggestions from the public, other concerned governmental
agencies, the scientific community, industry, or any other interested
party concerning this proposed rule are hereby solicited. Comments
particularly are sought concerning:
(1) Biological, commercial trade, or other relevant data concerning
any threat (or lack thereof) to these taxa;
(2) The location of any additional populations of these species and
the reasons why any habitat should or should not be determined to be
critical habitat as provided by section 4 of the Act;
(3) Additional information concerning the range, distribution, and
population size of these taxa; and
(4) Current or planned activities in the subject area and their
possible impacts on these species.
The final decision on this proposal will take into consideration
the comments and any additional information received by the Service,
and such communications may lead to a final regulation that differs
from this proposal.
The Endangered Species Act provides for a public hearing on this
proposal, if requested. Requests must be received within 45 days of the
date of publication of the proposal. Such requests must be made in
writing and addressed to the Field Supervisor of the Carlsbad Field
Office (see ADDRESSES section).
National Environmental Policy Act
The Fish and Wildlife Service has determined that an Environmental
Assessment or Environmental Impact Statement, as defined under the
authority of the National Environmental Policy Act of 1969, need not be
prepared in connection with regulations adopted pursuant to section
4(a) of the Endangered Species Act of 1973, as amended. A notice
outlining the Service's reasons for this determination was published in
the Federal Register on October 25, 1983 (48 FR 49244).
References Cited
A complete list of all references cited herein are available
upon request from the Carlsbad Field Office (see ADDRESSES section).
Author
The primary author of this proposed rule is Marjorie Nelson of
the Carlsbad Field Office (see ADDRESSES section).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, and Transportation.
Proposed Regulations Promulgation
PART 17--[AMENDED]
Accordingly, it is hereby proposed to amend part 17, subchapter B
of chapter I, title 50 of the Code of Federal Regulations, as set forth
below:
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.
2. It is proposed to amend Sec. 17.11(h) by adding the following,
in alphabetical order under INSECTS, to the List of Endangered and
Threatened Wildlife:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate population
--------------------------------------------------- Historic range where endangered or Status When listed Critical Special
Common name Scientific name threatened habitat rules
--------------------------------------------------------------------------------------------------------------------------------------------------------
* * * * * * *
Insects
* * * * * * *
Butterfly, Laguna Pyrgus ruralis lagunae.. U.S.A. (CA)............. NA..................... E ........... NA NA
Mountains skipper.
* * * * * * *
Butterfly, quino Euphydryas (=Occidryas) U.S.A. (CA), Mexico..... NA..................... E ........... NA NA
checkerspot. editha quino.
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Dated: July 24, 1994.
Mollie H. Beattie,
Director, Fish and Wildlife Service.
[FR Doc. 94-18932 Filed 8-1-94; 8:45 am]
BILLING CODE 4310-55-P
