(DRAFT) - Taxonomy
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
TAXONOMY
NAME - BUTTERFLY, SILVERSPOT, OREGON
OTHER COMMON NAMES - BUTTERFLY, SILVERSPOT, OREGON; FRITILLARY, HIPPOLYTA; SILVERSPOT, HIPPOLYTA; SILVERSPOT and OREGON
ELEMENT CODE -
CATEGORY - Terrestrial Insects
PHYLUM AND SUBPHYLUM - ARTHROPODA,
CLASS AND SUBCLASS - INSECTA,
ORDER AND SUBORDER - LEPIDOPTERA,
FAMILY AND SUBFAMILY - NYMPHALIDAE,
GENUS AND SUBGENUS - SPEYERIA,
SPECIES AND SSP - ZERENE, HIPPOLYTA
SCIENTIFIC NAME - SPEYERIA ZERENE HIPPOLYTA
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Oregon Silverspot Butterfly
Speyeria zerene hippolyta (W. Edwards, 1879)
KINGDOM: Animal GROUP: Insect
PHYLUM: Arthropoda CLASS: Insecta
ORDER: Lepidoptera FAMILY: Nymphalidae
The Oregon silverspot is a medium-sized, orange and brown
butterfly with black veins and spots on the dorsal wing surface, and
with a yellowish submarginal band and bright metallic silver spots
on the ventral wing surface. This subspecies is distinguished from
other subspecies by a somewhat smaller size and darker coloration
at the base of the wings, both which are adaptive morphological
traits for a persistently windy and foggy environment. The forewing
length averages about 27 mm for males and 29 mm for females (01,02).
The Oregon silverspot is also known as the Hippolyta Fritillary (or
silverspot) named for Queen Hippolyta of the Amazons of Greek
mythology (02). The Oregon silverspot was originally described from
three males and one female taken in Oregon - exact locality unknown
(Edwards, 1879) (02,03). An additional male from northern California
was included in the collection, however, authorities on this
butterfly do not consider the California population to presently
Taxonomy - 1 (DRAFT) - Taxonomy
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
belong biologically to the subspecies hippolyta. Howe gave the
subspecies' range as primarily the Oregon Coast Range, but states
that it has also been taken inland at Diamond Lake in Douglas
County, and inland along the Columbia River. The disposition of
these specimens is not documented.
The following is a chronological account of the discoveries of
all the recorded localities for the Hippolyta Silverspot. Included
are the collectors' names and the collections now containing the
specimens, if known (02).
Aug 18, 1895: Newport, OR, collector unknown (O.S.U. coll.)
1920's: Astoria vicinity, S Jewett, Jr. leg.
July 17, 1934: Squaw Creek (7 mil S of Yachats), Lane Co., OR,
S. Jewett, Jr. leg. (OSU coll.)
Aug 26, 1935: Netarts, Tillamook Co., OR, A. Walker leg. (R.
Albright coll.)
July 29, 1937: Oceanside, Tillamook Co., OR, R. Macy leg. (American
Museum of Nat. Hist., NY., type locality.)
July 10, 1938: Nahcotta (Long Beach Peninsula), Pacific Co., WA,
T. Kincaid leg. (D. Frechin coll.)
Aug 31, 1950: Westport, Harbor Co., WA, D. McCorkle leg. (McCorkle
and W. Howe coll.)
Sept 1, 1952: Cullaby Lake, Clatsop Co., OR, S. Jewett, Jr. leg.
(OSU coll.)
Aug 15, 1967: Cape Mears, Tillamook Co., OR, C.W. Nelson leg. (OSU
coll.)
Aug 15, 1967: Mt. Hebo, Tillamook Co., OR, C.W. Nelson leg. (OSU
coll.)
Sept 12, 1968: Boiler Bay, Lincoln Co., OR, D. McCorkle and G. Hawk
leg. (McCorkle coll.)
Aug 19, 1969: Yachats, Lincoln Co., OR, P. Hammond leg (Hammond
coll.)
Sept 2, 1970: Tenmile Creek, Lane Co., OR, D. McCorkle leg.
(McCorkle coll.)
Sept 8, 1971: Rock Creek - Big Creek, Lane Co., OR, D. McCorkle
leg. (McCorkle coll.)
Sept 10, 1973: Gearhart, Clatsop Co., OR, D. McCorkle leg. (McCorkle
coll.)
Sept 10, 1973: Saddle Mt., Clatsop Co., OR, D. McCorkle leg.
(McCorkle coll.)
Aug 24, 1975: Loomis Lake (Long Beach Peninsula), Pacific Co., WA,
R. Pyle leg. (Pyle coll.)
Descriptions, photographs, and drawings may be obtained from (02,
03,05,06).
Taxonomy - 2 (DRAFT) - Status
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
STATUS
Coded Status
T: Federal Threatened
Game (Consumptive Recreational)
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The Oregon silverspot butterfly (Speyeria zerene hippolyta) has
been designated as Threatened pursuant the Endangered Species Act of
1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540),
as amended. The subspecies has this status wherever found including
the States of Oregon and Washington. Critical Habitat has been
designated in portions of Sec. 10 and 15, T16S, R12W in Lake County,
Oregon (50 CFR 17.95(i)).
This subspecies is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild animal
(alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation, or foreign law; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
DOD -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public land under their control. Also responsible for
management/recovery on Department of Defense lands.
USFS -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public lands under their control. Also responsible
for management/recovery on Forest Service lands. The
Forest Service is responsible for integrating
management, protection, and conservation of Federally
listed species into the Forest Planning process
(36 CFR 219.19 and 219.20).
Status - 1 (DRAFT) - Status
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
STATE STATUSES AND LAWS:
STATE: Oregon
DESIGNATED STATUS: None
STATE: Washington
DESIGNATED STATUS: Recognized Threatened
ADMINISTRATIVE AGENCY: Dept. of Game
STATE STATUTE: Revised Code of WA Title 77.12.320
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
The Oregon silverspot butterfly is listed as Vulnerable in
the 1986 IUCN Red List of Threatened Animals.
ECONOMIC STATUSES:
The Oregon silverspot butterfly could be of monetary value to
collectors.
78/07/03:43 FR 28938/28945 - Proposed rule, Threatened, Crit. Hab.
80/03/26:45 FR 19864/19865 - Reproposal of Crit. Hab.
80/07/02:45 FR 44935/44939 - Final rule, Threatened, w/ Crit. Hab.
85/06/22:50 FR 29901/29909 - Five year Review
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
COASTAL
SOCIETY OF AMERICAN FORESTRY TYPES
SAF TYPE STAGE CLOSURE
Sitka spruce-western hemlock shrub--seedling
Sitka spruce-western hemlock young tree
Sitka spruce-western hemlock mature tree
Sitka spruce-western hemlock Old Growth
LAND USE -
Herbaceous Rangeland
Shrub and Brush Rangeland
Evergreen Forest Land
Habitat Associations - 1 COMMENTS ON HABITAT ASSOCIATIONS -
The Oregon silverspot butterfly has adapted to a highly
specialized and restricted environment. Basically, it is an early
successional meadow habitat highly modified by the physical
influences of the Pacific Ocean and its attending climate, which is
characterized by mild temperatures, heavy rainfall, and fog with a
salt spray influence from the adjacent ocean. The surrounding conifer
forest also plays a role in the overall habitat requirements of this
butterfly. The adjacent trees and brush provide cover from wind, an
overwhelming force in or near ocean habitat. The open meadows on
Mount Hebo, an apparent anomaly, provide the necessary habitat
requirement, unlike other inland areas. The precise reasons are
still unclear (01).
The habitat is similar on Mount Hebo with Viola adunca as the key
component. The distribution and composition of the flora may differ
slightly, but the habitat functions similarly to the salt-spray
meadow. The shallow soil apparently helps to keep this area in the
meadow stage (01).
Although the salt-spray meadow is the nursery area for the
butterfly and a key element of this species' habitat, it is a rather
harsh environment for the adults. Upon eclosion (metamorphosis of the
pupa into the adult butterfly), the adults generally move out of the
meadows into the fringe of conifers or brush where there is shelter
for more efficient heat conservation and nectaring flights. The
forest shelter may also be used for courtship and mating purposes.
Where such sheltered conditions exist, the adults will use various
nectar sources, both native and exotic species of plants. At the Big
Creek/Rock Creek colony site, several species are used, particularly
composites such as the native California aster, yarrow (Achillea
millefolium), and Indian thistle (Cirsium edule) and some exotics
such as false dandelion (Hypochaeris radicata) and tansy ragwort
(Senecio jacobaea) (02). The nectar supply is apparently adequate in
the meadow area and the adults will use these sources as well,
particularly during late summer when the ocean winds have diminished.
The impact of the exotic vegetation on the larval food plant (Viola
adunca) is not well known (02).
Females that have mated successfully wander over the forest
canopy and into flowered clearings up to a mile inland, presumably
using a variety of different nectar sources. Males normally remain
near the meadows in the forest fringe, nectaring within this area
(01).
Habitat Associations - 2 (DRAFT) - Food Habits
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE
LIFESTAGE FOOD FOOD PART
General Forb Leaves/Stems
General Forb Flowers/Fruit/Seed
Food Habits - 1 (DRAFT) - Environment Associations
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
ENVIRONMENTAL ASSOCIATIONS
Environment Associations - 1 (DRAFT) - Life History
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
LIFE HISTORY
FOOD HABITS:
The western blue violet (Viola adunca) is normally the only
species on which the Oregon silverspot can successfully feed and
develop as a larvae. However, in the laboratory, the butterflies will
accept other species of violets, and there is evidence that some
individuals on Mount Hebo are using another species of violet. The
adult females seek out violet host plants and lay their eggs on or
near them. Larvae feed on violets through the following spring and
summer. This plant is part of the salt-spray meadow vegetation and is
an obligatory component of the butterfly's habitat. Other features
of optimum habitat at the Big Creek/Rock Creek site include moderate
grass cover, including red fescue (Festuca rubra) used as shelter for
larvae. Within the adjacent forest shelter the adults will use
various nectar sources, both native and exotic species of plants. At
the Big Creek/Rock Creek colony site, several species are used,
particularly composites such as the native California aster, (Aster
chilensis), yarrow (Achillea millefolium), and Indian thistle
(Cirsium edule) and some exotics such as false dandelion (Hypochaeris
radicata) and tansy ragwort (Senecio jacobaea). The nectar supply is
apparently adequate in the meadow area and the adults will use these
sources as well, particularly during late summer when the ocean winds
have diminished (02).
HOME RANGE/TERRITORY:
The Oregon silverspot butterfly is nonterritorial. It does,
however, have specific habitat requirements since it has adapted to a
highly specialized and restricted environment (01). Basically it is
an early successional meadow habitat highly modified by the physical
influences of the Pacific Ocean and its attending climate. That is
characterized by mild temperatures, heavy rainfall, and fog with a
salt-spray influence from the adjacent ocean. The surrounding conifer
forest also plays a role in the overall habitat requirements of this
butterfly. The adjacent trees and brush provide cover from wind, an
overwhelming force in or near ocean habitat (01).
PERIODICITY:
The Oregon silverspot butterfly is diurnal and is
characteristically darker and smaller than inland subspecies of the
related bremnerii group. Evidence indicates that this is an adaptive
condition responsive to the persistent wind and frequent fog
characteristic of their breeding habitat during their flight period.
Butterflies, being heterothermic, depend usually upon solar
radiation to elevate their body temperature to a level sufficient to
allow the flight which is necessary for their foraging, mate seeking,
escape from predators, and oviposition activities. Rapid ovarian
development is also thermodependent (02).
MIGRATORY PATTERNS:
The Oregon silverspot butterfly is nonmigratory.
COVER/SHELTER REQUIREMENTS:
Life History - 1 (DRAFT) - Life History
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
Moderate grass cover within the salt-spray meadows, including red
fescue (Festuca rubra), are used as shelter for larvae (02).
The salt-spray meadow is a harsh environment for adult
butterflies. Upon eclosion (metamorphosis of the pupa into the adult
butterfly), the adults at the Big Creek/Rock Creek site generally
move out of the meadows into the fringe of conifers or brush where
there is shelter for more efficient heat conservation and nectaring
flights. The forest shelter may also be used for courtship and mating
purposes. Where such sheltered conditions exist, the adults will use
various nectar sources, both native and exotic species of plants (02).
REPRODUCTIVE SITE REQUIREMENTS:
Mating takes place in the fringe zone and out in the salt-spray
meadow proper when the summer winds diminish. Mating occurs through
August and September. Gravid females oviposit up to 200 or more eggs
singly amongst the salt-spray meadow vegetation near the violet host
plant, usually in late August and early September. Sites with good
sun exposure are favored. The eggs hatch in approximately 16 days and
the newly-hatched larvae wander short distances to find a suitable
site for diapause (suspend growth for overwintering). The larvae end
diapause sometime in early spring and begin to feed on the violet
leaves. As the larvae grow, they pass through 5 molts before they
pupate. The larger instars sometimes retreat to sheltered sites up to
several centimeters away from the foodplants where they are afforded
thermal cover and cover from potential predators. After at least a
2 month larval stage, the larvae move to well-hidden shelter sites
where they pupate. Approximately 2 or more weeks later, the
butterflies eclose. Shortly thereafter, their wings and other body
parts harden and they escape the windy, cool meadow (02).
REPRODUCTIVE CHARACTERISTICS:
The males tend to eclose before females, as is characteristic for
Speyeria species in general. They apparently require a period of
maturation, dependent upon successful nectaring and thermal exposure.
Once sexual maturity is reached, a male's chance of successful mating
involves both a time and a space dimension. Thus, the longer his time
of activity each day, and the closer he is to the eclosing females
when he is mate searching, the greater his chance of successful
competition for the females (02).
If a male is to remain in the windy meadows upon eclosion, his
maturation rate would be seriously impaired, both by thermal
insufficiency and by unsuccessful nectaring. Furthermore, it would be
difficult to patrol for females in the face of the wind. Thus, it is
not surprising that the males retreat to sheltered areas where
convective heat loss is minimized and nectaring flights are
unimpaired (02). However, the freshly eclosed females must leave the
meadows as well, for similar reasons: thermal requirements for rapid
egg development and nectaring flight. Thus the mature males
concentrate in a fringe around the meadow at areas where the females
are likely to pause as they exit. These are mostly at the first
locations providing sufficient protection for efficient nectaring
flights. Here the patrolling males intercept the virgin females
leaving the windy meadows (02).
Life History - 2 (DRAFT) - Life History
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
PARENTAL CARE:
No parental care.
POPULATION BIOLOGY:
Little information has been compiled to date regarding survival
rate, mortality rate, rate of increase, sex ratio, recovery potential,
turnover rate, longevity, etc.
On the other hand, the major limiting factors affecting this
species are related primarily to the limitation of suitable habitat.
The highly specialized salt-spray meadow habitat within the
geographical range of the Oregon silverspot butterfly was never
common. This early seral community has always had a patchy
distribution, occurring only where fire, salt-laden winds, or other
natural or man-related occurrences (e.g., grazing, controlled
burning) have maintained an open meadow. Evidence suggests that such
habitat has been much more extensive than it is today. Historical
accounts show the butterfly and its habitat as locally common within
its range. However, good habitat has steadily declined due to
various human influences. Seaside meadow sites have been used for
residential and business establishments, public parkland development,
and parking areas or lawns. Excessive use of the salt-spray meadows
by grazing animals or off-road vehicles has directly eliminated
habitat (02). Secondary impacts of people's activities, introduction
of exotic plants, and alteration of the natural fire regime with
subsequent succession of meadows to brush and stunted woodland, have
also contributed to a reduction in suitable habitat (01).
Other limiting factors which affect total population numbers do
not appear to have a significant impact. Predators and parasites such
as ground beetles or spiders very likely attack the small larvae, and
shrews, birds and meadow mice may attack the larger larvae. Local
instances of avian predation on adults have been noted (02). There is
no evidence, however, to suggest that predators or parasites are a
significant problem. Road kills of adults where U.S. Highway 101
bisects the Big Creek/Rock Creek population probably take a notable
number of butterflies. The relatively high reproductive potential of
the butterfly would appear to prevent this from affecting the
population as a whole (02). Collecting by people is not known to be a
significant problem (01).
Habitat destruction is unquestionably the reason for the
threatened status of the butterfly today. It should be noted,
however, that as colony size is reduced by habitat loss, restricted
genetic variability and/or catastrophic events can ultimately cause
the extinction of these small populations (02).
SPECIES INTERRELATIONSHIPS:
The western blue violet (Viola adunca) is the obligatory plant
host for the Oregon silverspot. This plant is normally the only
species on which the butterfly can successfully feed and develop as a
larvae. The violet is a component of the limited salt-spray meadow
habitat.
OTHER LIFE HISTORY DESCRIPTORS:
Life History - 3 (DRAFT) - Life History
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
None.
Life History - 4 (DRAFT) - Management Practices
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Prescribed/controlled burning of habitat
Beneficial Controlling/Restricting Off-Road Vehicles
Beneficial Restricting/regulating human disturbance of populations
Beneficial Reducing Urban Light Radiation
Beneficial Land Acquisition
Beneficial Controlling/Restricting Pesticide Use
Beneficial Reforestation
Beneficial Maintaining Early Stages of Succession
Beneficial Controlling/Removing Native Vegetation
Beneficial Stocking captive-reared wild-strain animals
Beneficial Transplanting wild animals
Beneficial Restricting Poaching
Adverse Off Road Vehicles
Existing Off Road Vehicles
Adverse Rural Residential/Industrial Areas
Existing Rural Residential/Industrial Areas
Adverse Recreational development
Existing Recreational development
Adverse Exotic/Feral/Introducted Species
Existing Exotic/Feral/Introducted Species
Adverse Grazing
Existing Grazing
Adverse Vegetation Composition Changes
Existing Vegetation Composition Changes
Adverse Suppressing wildfire
Existing Suppressing wildfire
COMMENTS ON MANAGEMENT PRACTICES -
The Oregon silverspot butterfly is endemic to the coastal zone
along the southern Washington coast and central and northern Oregon
coast. It occurred historically along its narrow restrictive range in
coastal salt spray meadows and adjacent forests from north of
Florence, Oregon to Grays Harbor, Washington. It is postulated that
the northern limit of this butterfly's range is restricted by the
increasing frequency of summer storms which preclude the butterfly's
establishment (02). The barrier to the southern extension of this
subspecies is apparently the vast dune formation of the central
Oregon coast (01).
The major limiting factors affecting this species are related
primarily to the limitation of suitable habitat (01). The highly
specialized salt spray meadow habitat within the geographical range
of the Oregon silverspot butterfly was never common. This early seral
community has always had a patchy distribution, occurring only where
fire, salt-laden winds, or other natural or man-related occurrences
(e.g., grazing, controlled burning) have maintained an open meadow.
Evidence suggests that such habitat has been much more extensive than
it is today. Historical accounts show the butterfly and its habitat
as locally common within its range. However, good habitat has
Management Practices - 1 (DRAFT) - Management Practices
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
steadily declined due to various human influences. Seaside meadow
sites have been used for residential and business establishments,
public parkland development, and parking areas or lawns. Excessive
use of the salt spray meadows by grazing animals or off-road vehicles
has directly eliminated habitat (02). Secondary impacts of people's
activities, introduction of exotic plants, and alteration of the
natural fire regime with subsequent succession of meadows to brush
and stunted woodland, have also contributed to a reduction in
suitable habitat (01).
Road kills of adults where U.S. 101 bisects the Big Creek/Rock
Creek population probably take a notable number of butterflies, but
probably do not affect the population as a whole (02). A proposed
golf course and housing development at Clatsop Plains, Clatsop Co. was
planned in 1986, which could have impacted a primary breeding area. A
Habitat Conservation Plan was being considered for the area (04).
APPROVED PLAN:
U.S. Fish and Wildlife Service. 1982. Oregon Silverspot Butterfly
Recovery Plan. U.S. Fish and Wildl. Serv., Portland, OR. 33 pp.
The actions to be implemented for the recovery of the species
as outlined in the approved recovery plan for the Oregon silverspot
butterfly include:
1. Determine the number of individuals per disjunct population and
the number of populations distributed throughout the butterfly's
range necessary to restore the Oregon silverspot butterfly to a
delisted status;
2. Secure areas (land acquisition) suitable for reintroduction of the
butterfly and its food plant(s);
3. Initiate propagation and reintroduction programs as needed;
4. Protect and enhance existing populations;
5. Establish and maintain additional colonies in restored habitats or
suitable new habitats;
6. Monitor the status of the butterfly and its natural and created
habitats;
7. Develop public awareness of butterfly recovery needs and
endangered species programs generally, and restrict poaching;
8. Limit human access to and recreational uses of the butterflies
habitat;
9. Restrict the use of off-road vehicles, camping, pesticides, and
direct lighting in the habitat and its surrounding habitat areas.
Prescribed burning, scarification or chemicals may be used to
maintain early successional stages but must be controlled.
Management Practices - 2 (DRAFT) - References
Species BUTTERFLY, SILVERSPOT, OREGON
Species Id ESIS501002
Date 13 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 U.S. Fish and Wildlife Service. 1982. Oregon Silverspot Butterfly
Recovery Plan. U.S. Fish and Wildl. Serv., Portland, OR. 33 pp.
02 McCorkle, D.V., P. Hammond, and G. Penington. 1980. Ecological
investigation report: Oregon silverspot butterfly (Speyeria zerene
hippolyta). For. Serv. USDA. Pac. Northwest Region. Siuslaw NF.
03 Edwards, W.H. 1879. Descriptions of new species of North American
butterflies. The Canadian Entomologist. Vol. XI. No. 5.
04 U.S. Fish and Wildlife Service. 1986. Regional briefs; Region 1.
Endangered Species Tech. Bull. Vol XI, No. 7:9.
05 Dornfield, E.J. 1980. The butterflies of Oregon. Oregon Timber
Press.
06 Howe, W.H. 1975. The butterflies of North America. New York:
Doubleday and Co., Inc.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 U.S. Fish and Wildlife Service. 1982. Oregon Silverspot Butterfly
Recovery Plan. U.S. Fish and Wildl. Serv., Portland, OR. 33 pp.
02 Hammond, P.C. and D.V. McCorkle. 1982. The 1982 field survey
results for the Oregon silverspot butterfly (Speyeria zerene
hippolyta). OES, U.S. Fish and Wildl. Serv., Portland, OR.
03 McCorkel, D.V., P. Hammond, and G. Penington. 1980. Ecological
investigation report: Oregon silverspot butterfly (Speyeria zerene
hippolyta). For. Serv., USDA. Pac. Northwest Region. Siuslaw NF.
References - 1