CONSERVATION AGREEMENT
MINK LAKE BASIN SPOTTED FROG POPULATION
I.
SPECIES INVOLVED
Oregon Spotted Frog, Rana pretiosa
II.
INVOLVED PARTIES
A. U.S. Fish and Wildlife Service (USFWS)
Oregon State Office
2600 SE 98th Ave, Suite 100
Portland, OR 97266
Contact: Laura Todd
Telephone: (503) 231-6179
Fax: (503) 231-6195
e-mail: Laura_Todd@fws.gov
B. U.S. Forest Service (USFS)
McKenzie Ranger District
Willamette National Forest
McKenzie Bridge, OR 97413
Contact: Cheryl Friesen
Telephone: (541) 822-3381
Fax: (541) 822-7254
e-mail: cfriesen@fs.fed.us.
C. Oregon Department of Fish and Wildlife (ODFW)
3150 Main Street
Springfield, OR 97478
Contact: Jeff Ziller
Telephone: (541) 726-3515
Fax: (541) 726-2505
e-mail: jeffrey.s.ziller@state.or.us
III.
AUTHORITY, PURPOSE, OBJECTIVE, AND MANAGEMENT GOAL
A. The authority for the U.S. Fish and Wildlife Service (USFWS) to enter into this
voluntary Conservation Agreement derives from the Endangered Species Act of 1973, as
amended; the Fish and Wildlife Act of 1956, as amended; and the Fish and Wildlife
Coordination Act, as amended.
B. The purpose of this agreement is to formally document the intent of the cooperators to
protect, conserve, and restore the spotted frog population in the Mink Lake Basin.
Conservation Agreement cont.
C. The objective of this agreement is to provide a means for protection and conservation
of the spotted frog population in the Mink Lake Basin
D. The management goal of this agreement is to stabilize or increase the population at
Mink Lake Basin, reduce threats, and increase distribution among available suitable
habitats. Any signficant declines documented for more than one year from the most
recent survey for any subpopulations will initiate a review of population status. In a
timely manner, a determination will be made whether there is a need for management
action. Note that small declines may be attributable to natural variation or variation in
surveys, and should be monitored closely (see Monitoring Strategy in Section X).
IV.
DURATION OF THIS CONSERVATION AGREEMENT
The duration of this Conservation Agreement is for 10 years following the date of the last
signature. The parties involved will review the Conservation Agreement and its effectiveness
every 2 years to determine whether it should be revised. During the last month in which it is
valid, the Conservation Agreement must be reviewed and either modified, renewed, or
terminated.
If some portion of this Agreement cannot be carried out or if cancellation is desired, the party
requesting such action will notify the other parties within one month of the changed
circumstances. When and if it becomes known that there are threats to the survival of the subject
candidate species that are not or cannot be resolved through this or any Conservation Agreement,
the species will be retained in or reassigned to category 1 and an appropriate listing priority
assigned, unless the species is listed.
V.
STATUS AND DISTRIBUTION OF SPECIES
A. Species Description
The Oregon spotted frog is a medium-sized frog, with adults raging from 2.5 to 4 inches in body
length (McAllister and Leonard 1997). Females are typically larger than males. Females reach
up to 4 inches and males to 3 inches (Leonard et al. 1993). Black spots characteristically cover
portions of dorsal skin on the head, body, and legs. The abdomen is typically red. This red
coloration increases in coverage and depth with age. The relatively short hind legs, upturned
eyes, and fully webbed toes can be used to distinguish the spotted frogs from other native frogs.
The Oregon spotted frog has a weak call consisting of a rapid series of six to nine low clucking
notes, described as sounding like a distant woodpecker's tapping. However, this species rarely
vocalizes except during the breeding season (Leonard et al. 1993). Males will call at any time,
both day and night, to attract females (McAllister and Leonard 1997).
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Conservation Agreement cont.
B. Habitat Description
Oregon spotted frogs inhabit emergent wetland habitats. This species is the most aquatic native
frog in the Pacific Northwest, and is usually found near surface waters (e.g., springs, ponds,
lakes, sluggish streams) that include a zone of shallow water and abundant emergent or floating
aquatic plants. This zone provides important basking and escape cover from predators (Leonard
et al. 1993, Corkran and Thoms 1996, McAllister and Leonard 1997). Oregon spotted frogs
seem to prefer fairly large, warm marshes (> approximately 9 acres) that can support a large
enough population to persist despite high predation rates (Hayes 1994). In Washington, spotted
frogs selected shallow water (4-12 inches deep), with less emergent vegetation, but more
submergent vegetation than random points. They avoided dry, upland areas of pasture grass
(Watson et al. 1998).
Adult frogs move to remnant pools during low water levels and disperse from these pools during
increased precipitation in September and October (Watson et al. 1998). Monitored Oregon
spotted frogs stayed within a study area throughout the year; telemetered frogs stayed within
2600 feet of capture locations. Recaptures of Oregon spotted frogs in the Buck Lake, Oregon,
population indicated that adult frogs may move less than 300 feet between years (Hayes 1998b).
Oregon spotted frogs generally breed in shallow pools (2-12 inches deep) that are near flowing
water, or which may be connected to larger bodies of water during seasonally high water or at
flood stage (McAllister and Leonard 1997, Pearl and Bury 2000). Eggs are generally deposited
before significant vegetation growth in early spring, and are often laid in areas characterized by
grasses, sedges, and rushes (McAllister and Leonard 1997).
Oregon spotted frogs are thought to remain in warmwater marshes except during the
overwintering period. Recent data suggests that overwintering sites are associated with springs
or other locations with low, continuous flow conditions. This choice of overwintering site may
reflect an avoidance of sites that could freeze (M. Hayes, pers. comm. 1999). This species is
generally inactive during the winter, except on warmer days. Oregon spotted frogs apparently
burrow in muddy, silty substrates or clumps of emergent vegetation when inactive during periods
of prolonged or severe cold (Dickerson 1907, McAllister and Leonard 1997).
C. Life History
Breeding occurs as early as February/March, but can be as late as May/June (Leonard et al. 1993,
Pearl 1999) depending on elevation and snow pack conditions. Female Oregon spotted frogs
may breed at 3 years old, and males are generally thought to first reproduce in their second year
(Licht 1986, McAllister and Leonard 1997). Male Oregon spotted frogs are not territorial and
may gather in large groups of 25 or more individuals (Leonard et al. 1993). Males and females
probably separate soon after egg-laying, with females returning to fairly solitary lives. Males
may stay at the breeding site, possibly for several weeks, until oviposition is completed
(McAllister and Leonard 1997).
Oregon spotted frog eggs are extremely vulnerable due to the species' laying habits. Females
may deposit their egg masses at the same locations in successive years, indicating the sites may
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Conservation Agreement cont.
have unique characteristics (Licht 1971). Use of traditional oviposition sites that may have
limited availability because of unique characteristics, and the possibility that adults may have
limited flexibility to switch sites, makes the Oregon spotted frog particularly vulnerable to
habitat changes at oviposition sites (Hayes 1994).
Egg masses are generally laid communally in groups of a few to several hundred (Licht 1971,
Nussbaum et al. 1983, Cook 1984, Hayes et al. 1997, Engler and Friesz 1998). Eggs are laid in
shallow areas, often associated with a permanent water body (Leonard et al. 1993, Pearl and
Bury 2000). This breeding habit result in high mortality rates for eggs due to desiccation and/or
freezing (Pearl and Bury 2000, M. Hayes, pers. comm.). Such shallow areas warm quickly in
spring, which is thought to hasten egg development (McAllister and Leonard 1997, C. Pearl,
unpubl. data).
Eggs usually hatch within 3 weeks after oviposition. Tadpoles are grazers, having rough tooth
rows for scraping plant surfaces and ingesting plant tissue and bacteria. They also consume
algae, detritus, and probably carrion (Licht 1974, McAllister and Leonard 1997). Tadpoles
metamorphose into froglets (0.8-1.3” in length) during their first summer (Leonard et al. 1993,
C. Pearl unpubl. data). Live animals, primarily insects but also smaller anurans, are the prey of
post-metamorphic Oregon spotted frogs.
There are a number of documented and potential natural predators of Oregon spotted frogs.
Several introduced fish, as well as bullfrogs (Rana catesbeiana), have been transplanted into
their historic range and may have contributed to the decline of this and other species of frogs
(Hayes and Jennings 1986, Hayes 1994, U.S. Fish and Wildlife Service 1996, McAllister and
Leonard 1997).
VI. MINK LAKE BASIN POPULATION
The Mink Lake Basin lies in the Three Sisters Wilderness Area of the McKenzie Ranger District
in the Willamette National Forest. It provides the headwaters to the south Fork McKenzie River
drainage, and is characterized by over 100 ponds, lakes, and wetlands along the west side of the
Cascade Crest between 4600’-5600’ above sea level. Immediately to the south and east lie
additional water bodies in the headwaters of the Cultus drainage, an upper tributary of the
Deschutes River. Many wetlands in these upper basins are near the assumed elevational limit of
the Oregon spotted frog. The highest known population occurs at 5250’ in the Klamath Basin
(Hayes et al. 1997).
As of 1999, there were two known Oregon spotted frog populations in the Mink Lake Basin: the
Penn Lake/Cabin Meadows complex and an Unnamed Marsh north of Mink Lake. The historic
distribution of the Oregon spotted frog in the Mink Lake Basin is not well understood, but
museum collections and specific observations by herpetologists suggest they were once more
widespread than at present. The collection of seven juveniles prior to 1975 suggests that Goose
Lake (similar in structure and less than 1.5 km from Penn Lake) historically supported Oregon
spotted frog reproduction (R.G. Altig, pers. comm.). Dr. R.M. Storm (O.S.U. Zoology Emeritus,
pers. comm.) also noted the presence of Oregon spotted frog(s) near Mink Lake prior to 1975.
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Conservation Agreement cont.
Subsequent surveys at the Goose Lake historic site have detected one adult spotted frog and no
breeding (Pearl 1999, Pearl and Bury 2000). Surveys at and around Mink Lake have failed to
detect any life stages of the Oregon spotted frog, so declines are likely in these areas (Pearl 19971999, Pearl and Bury 2000). The presence of adult spotted frogs at Penn Lake was confirmed in
1993 (Hayes 1994). That survey detected very few individuals, and suggested a strongly adultbiased population with negligible recruitment in the short term (Hayes 1994).
The connection between this population and others within the range is not well understood.
Mink Lake spotted frogs could be remnants from historic lower elevation Willamette valley
populations. They could also be remnants from populations east of the Cascade crest. Studies
on genetics and habitat connectivity currently underway may provide more information on the
relationships in distribution (L.Todd, personal comm.).
Recent work has focused on the Penn Lake habitat complex, and surveys in 1997, 1998, and
1999 suggest some demographic recovery from the 1993 surveys (Pearl 1997-1999, Pearl and
Bury 2000). Three other lentic sites proximal to the breeding sites at the Penn Lake complex and
the Unnamed Marsh have held spotted frogs (2 adults and 1 juvenile) during at least one survey
(Pearl 1997, 1999). Breeding surveys conducted in spring of 1999 suggest both the Penn Lake
complex and the Unnamed Marsh populations are likely less than 25 breeding females (Pearl and
Bury 2000).
VII.
PROBLEMS FACING THE SPECIES: Rangewide
Recent surveys of an estimated 95 percent of suitable sites across the spotted frog’s geographic
range, including historic sites, indicate that this species may have been lost from up to 90 percent
of its former range (Hayes 1997, Hayes et al.1997). The Oregon spotted frog is now known from
only 28 sites in Washington and Oregon and at 3 sites in British Columbia (Hayes 1997,
McAllister and Leonard 1997, Pearl 1999, Pearl and Bury 2000, K. McAllister, pers. comm.
1998, R. Haycock, pers. comm. 1999). This species generally persists in only the most suitable
habitat remaining within its historic range. These sites are generally located high in the drainage,
have the least altered hydrology, and have the fewest introduced predators in comparison with
historic localities where Oregon spotted frogs are no longer detected (Hayes et al. 1997).
Several aspects of the Oregon spotted frog's life history make it particularly vulnerable to habitat
alterations: (1) communal egg laying at sites used year after year restricts the number of
reproductive sites; (2) the species' warmwater requirement results in habitat overlap with
introduced warmwater fish; (3) the active season warmwater requirement may limit suitable
habitat in the cool climate of the Pacific Northwest; and (4) the species may be vulnerable to the
potential loss or alteration of springs used for overwintering (Hayes et al. 1997).
Wetland loss is a significant problem for this species. Conservative estimates from Washington
indicate that over 33 percent of wetlands were lost between pre-settlement times and the 1980's
as agriculture and an increasing population created demands for dry land for grazing livestock,
growing crops, and for development. Wetlands were drained, diked, and filled (Canning and
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Conservation Agreement cont.
Stevens 1990, McAllister and Leonard 1997). Similar losses have been observed in Oregon,
particularly in the Willamette Valley (e.g., Sedell and Froggat 1984). Marsh habitat losses in the
Willamette basin is estimated to exceed 95 percent of what was historically suitable habitat for
Oregon spotted frogs. Marsh habitat losses in the Klamath Basin is estimated to exceed more
than 98 percent (Hayes 1997).
Changes in hydrology currently threaten many extant Oregon spotted frog populations. Twentyone of twenty-eight Oregon spotted frog sites (75%) surveyed have had some human-related
hydrological alterations, ranging from minor changes (e.g., local ditching around springs) to
substantial changes, including major modifications of historic flow patterns (Hayes 1997, Hayes
et al. 1997, Pearl 1997 and 1999). Dams in the upper watersheds of the Willamette Valley,
Deschutes drainage, and the Puget Trough have significantly reduced the amount of shallow
overflow wetland habitat historically created by natural flooding and used by the Oregon spotted
frog. Inundation of large marsh complexes and habitat fragmentation due to the construction of
reservoirs in the Cascades have eliminated and degraded habitat of the Oregon spotted frog as
well. Relatively small areas of suitable habitat (< 63 acres) remain at 82 percent of Oregon
spotted frog populations surveyed, indicating a number of the remaining Oregon spotted frog
sites may be at risk because so little suitable habitat is available (Hayes 1997; Hayes et al. 1997;
Pearl 1997, 1999).
Changing water levels at critical periods in the Oregon spotted frog's life cycle, whether natural
or man-induced for land management practices, can negatively affect the species (M. Hayes,
pers. comm.). Reduction in water levels may expose Oregon spotted frogs to predation as a
result of reducing cover and confining the frogs to smaller areas where they are more vulnerable
to predators, including introduced fish. Due to the tendency for communal oviposition, water
level reduction during the breeding season could result in the loss of significant portions of that
year’s reproductive effort. Excessive seasonal flooding at critical periods can result in the loss
of the shallow wetlands needed for egg laying and development.
Water quality and the absorption of contaminants in water through the skin and gills in immature
forms may also threaten this species (Marco and Blaustein 1999). Amphibians in general are
susceptible to the effects of poor water quality. They may also ingest contaminated prey.
Acidification of water, as reflected by low pH, can inhibit fertilization and embryonic
development in amphibians; can reduce their growth and survival through physiological
alterations; and can produce developmental anomalies (Hayes and Jennings 1986, Boyer and
Grue 1995, Northern Prairie Wildlife Research Center 1997). A low pH may enhance the effects
of other factors, such as mobilization of heavy metals from sediments. Concern about the effects
of acid rain in western aquatic habitats has increased (Boyer and Grue 1995).
Pesticides, herbicides, heavy metals, nitrates and nitrites, and other contaminants introduced into
the aquatic environment from urban and agricultural areas are known to negatively affect various
life stages of a wide range of amphibian species, including ranid frogs (Hayes and Jennings
1986, Boyer and Grue 1995, Hecnar 1995, Environment Canada 1998, Northern Prairie Wildlife
Research Center 1999).
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Conservation Agreement cont.
Development threatens Oregon spotted frog habitat at several sites. Development would likely
result in habitat loss, hydrological changes, as well as changes in water quality and introduction
of contaminants into the aquatic environment.
Livestock grazing may pose a threat to some occupied sites, but impacts are thought to vary by
livestock numbers and the intensity of grazing. Fourteen of twenty-eight (50%) sites surveyed
were directly or indirectly influenced by livestock grazing (Hayes 1997, Hayes et al. 1997, Pearl
1999). Livestock grazing may, in some instances, benefit this frog by maintaining openings in
the vegetation in highly disturbed wetland communities, but it may negatively affect this species
if the habitat has been previously degraded (Hayes 1997, Hayes et al. 1997, McAllister and
Leonard 1997), particularly at springs used as overwintering sites for Oregon spotted frogs. The
addition of urine and feces by livestock may also affect water quality (Hayes 1997).
Threats exist from exotic plant invasions, such as reed canarygrass (Phalaris arundinacea).
Aggressive exotics can completely alter the structure of wetland environments and can create
dense areas of vegetation that may be unsuitable as Oregon spotted frog habitat (McAllister and
Leonard 1997). Exotic vegetation was found at 71% of Oregon spotted frog sites surveyed.
Reed canarygrass dominated large areas at lower elevations and is apparently continuing to
broaden its range to higher elevations (Hayes 1997, Hayes et al. 1997).
Succession (changes in plant communities) may be a factor threatening all Oregon spotted frog
sites, particularly where marsh-to-meadow changes are occurring. Recent losses of frog habitat
apparently have been considerably greater than habitat gains (Hayes 1997, Hayes et al. 1997).
Such succession-related losses may be accelerated by human activities, livestock grazing, and
development. Loss of Oregon spotted frogs in 1991 from the Paulina Prairie site, a historic site
in Oregon, was probably due to a number of factors including habitat degradation from livestock,
but also from drought.
Naturally occuring events, such as disease, can strongly impact small populations that are
already stressed by other factors (e.g., drought or low food availability). Amphibians are known
to be affected by a variety of diseases (Berger 1999). There is little information on the specific
effects of disease and parasitism on Oregon spotted frogs. Red-leg syndrome has been identified
from a number of declining amphibian populations. Since this syndrome has been linked to
several pathogens, and immune system disruption is also possible, the underlying causes of the
declines are unclear. The fungus Saprolegnia has been suggested as one of the causes of
amphibian declines in the Pacific Northwest (Blaustein et al. 1994a, 1994b), but this fungus is
apparently more serious for western toads in the Oregon Cascades (Blaustein et al. 1994a).
Amphibians exposed to UV-B may be more susceptible to pathogens and parasites that can
interfere with normal development and increase mortality. Kiesecker and Blaustein (1997)
found increased mortality associated with the fungus Saprolegnia ferax in amphibian embryos
exposed to UV-B, indicating the possibility of a synergistic effect between the fungus and UV-B.
Field experiments conducted in the Oregon Cascade Mountains determined that ambient levels
of UV-B from the sun can cause high rates of mortality and deformities in amphibian embryos
(Blaustein et al. 1997). Amphibian species that lay their eggs in areas with little vegetative
cover, as the Oregon spotted frog does, may experience greater exposure to UV-B. However,
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Conservation Agreement cont.
field enclosures and enzymatic characterization suggest Oregon spotted frogs are resistent to
ambient UV-B insolation (Blaustein et al. 1999).
The warm water habitat requirement of the Oregon spotted frog makes it unique among native
ranids of the Pacific Northwest, but also exposes this species to a number of introduced fish,
contributing to losses of populations (Hayes and Jennings 1986, Hayes 1997, Hayes et
al. 1997, McAllister and Leonard 1997). Oregon spotted frogs, which are palatable to fish, did
not evolve with these introduced species and may not have the mechanisms to avoid predatory
fish that prey on the tadpoles of native amphibians. The negative effects of introduced fish on
the Oregon spotted frog have been suggested by demographic data showing that sites with a
disproportionate ratio of older spotted frogs to juvenile frogs (i.e., poor recruitment) also have
significant numbers of brook trout (e.g., Penn Lake and Fourmile Creek, Oregon) and/or fathead
minnow (Wood River Ranch, Oregon) (Hayes 1997, 1998; Pearl 1997, 1999). A study of the
impacts of introduced trout on Columbia spotted frog (Rana luteiventris) populations in Idaho
revealed that most stocked lakes contained fewer than 10 adult frogs and no egg masses or
tadpoles (Pilliod and Peterson 1997). Surveys found at least one introduced predator in 20 of 24
sites surveyed in British Columbia, Washington, and Oregon (Hayes 1997). Predator presence
has not been surveyed and/or reported, but is likely, at the 10 newly discovered localities found
in 1998. Brook trout, occurring at 18 sites, are the most frequently recorded introduced predator
and apparently occurs with the Oregon spotted frog at coldwater springs where this species
probably overwinters (Hayes et al. 1997, Pearl 1999).
Bullfrogs have been introduced into the Pacific Northwest from eastern North America.
Bullfrogs are thought to possess a competetive advantage over northwestern ranid frogs because:
1) bullfrogs have evolved with many of the introduced fish species and developed defenses
against these predators; 2) bullfrog tadpoles are not palatable to all fish or birds (Kruse and
Francis 1977, McAllister and Leonard 1997); 3) bullfrog tadpoles may displace tadpoles of
other frog species from warmer water where conditions are optimal for development (Hayes
1994, Kiesecker and Blaustein 1998) to cooler water, which slows development; and 4) bullfrog
tadpoles are more resistant to the effects of pesticides and heavy metals than other ranid frogs
(Hayes and Jennings 1986). Bullfrogs may affect native frogs, either directly by eating them or
indirectly by outcompeting or displacing them from their habitat or from optimal conditions,
although specific interactions are poorly known (Pearl and Hayes, in review).
Changes in water levels due to drought can cause seasonal loss of habitat and degradation of
essential shoreline vegetation. Hayes (1997) assessed 38 percent Oregon spotted frog sites as
having a moderate to high risk from drought (i.e., the potential for a drop in water level that
could reduce or eliminate the species' habitat). Sites with the greatest risk included sites
depending on surface flow rather than flows from springs and having low precipitation levels.
Sites with the greatest risk from drought are in Oregon in the Klamath and Deschutes Basins
(Hayes 1997, Hayes et al. 1997).
The USFWS has carefully assessed the best scientific and commercial data available regarding
the past, present, and future threats faced by the Oregon spotted frog. These data indicate there
have been drastic losses in Oregon spotted frog habitat and populations. The remaining habitat
and populations face imminent threats due to a wide range of known and potential impacts
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Conservation Agreement cont.
throughout all or a significant portion of its range.
VIII. PROBLEMS FACING THE SPECIES: In Conservation Agreement Area
By using a scoring system similar to that employed by Hayes (1997) and Pearl (1999) estimated
relative importance of threats to the Mink Basin populations. Stressors qualitatively treated
were: 1) Site Size, 2) Introduced Fish, 3) Drought Effects, 4) Habitat Succession, and 5)
Isolation Effects. Among the four sites evaluated, including two in the Deschutes Drainage, the
Unnamed Marsh site was found to be at highest risk, with Penn Lake complex at moderate
overall risk.
The Unnamed Marsh site was given ‘High Risk’ values for drought, succession, and isolation,
while Penn Lake was given moderate values for those three variables. Threats imposed by
vegetative succession are difficult to assess, but may pose distinct problems where such rates are
increasing due to hydrological alteration.
Both breeding sites support high densities of introduced brook trout (Salvelinus fontinalis),
which are now widespread through the lower Basin (Pearl 1999). The Penn Lake complex also
supports a reproducing population of Hackleman cutthroat trout (Oncorhunchus clarki clarki).
The Penn Lake complex received ‘High Risk’ values for introduced fish (brook trout abundant,
breeding on-site), while Unnamed Marsh was given a ‘Moderate Risk’ value (lower density of
brook trout, potentially not breeding directly on-site). Pearl (1999) concluded that the threat of
introduced brook trout is probably the most significant to this population, and that fish have the
potential to interact with low water conditions to exacerbate low recruitment in those years. This
hypothesis has also been stated by Hayes (1997). The isolation of these sites from other
populations, combined with the relatively low dipersal potential of this species and the likelihood
that dispersal movements and overwintering occur in aquatic corridors/sites that also support
introduced fish, are conditions of high concern. Evidence from other regions in the western
United States suggests that montane ranids can exist in a metapopulation structure that is in part
dependent upon recolonization (Bradford et. al 1993 and Pilliod et al. 1996). Additional details
regarding the relative importance of these and other population stressors is critical to improve
conservation of the Oregon spotted frog in montane habitats.
IX. CONSERVATION ACTIONS THAT WILL BE CARRIED OUT
The USFWS, USFS, and ODFW shall implement the following as allowed under laws,
regulations, and policies effective at the time of the proposed actions and subject to limitations
in funding.
A.
THE U.S. FISH AND WILDLIFE SERVICE SHALL:
1. Provide funding as possible to support monitoring, education, and other conservation
efforts.
2. Assist in development of education materials.
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Conservation Agreement cont.
3. Provide technical assistance upon request.
4. Maintain current records of spotted frog locations and population status.
5. Cooperate with the USFS and ODFW to define and identify Spotted Frog Conservation
Areas in the Mink Lake Basin (See Section IX D for details).
B.
THE U.S. FOREST SERVICE SHALL:
1.
2.
3.
4.
5.
Develop methods to protect known sites of spotted frogs.
Survey potential habitat in a timely manner.
Monitor known, historic, and potential habitat. (See Section X for details)
Develop educational materials for wilderness users.
Provide notice to all cooperators for comment if any planning or maintenance activities
are scheduled to occur.
6. Develop a management plan for recreational developments (i.e. trails).
7. Coordinate and be the lead agency to define and identify Spotted Frog Conservation
Areas with other cooperators (See section IX D for details).
C.
THE OREGON DEPARTMENT OF FISH AND WILDLIFE SHALL:
1. Review fish stocking practices for potential impacts.
2. Evaluate potential to remove non-native fish.
3. Cooperate with the USFS and USFWS to define and identify Spotted Frog Conservation
Areas where introduced fish management may be modified.
D.
PROCESS FOR DEFINING AND IDENTIFYING CONSERVATION AREAS
1.
2.
3.
4.
5.
Identify historic fishless lakes.
Identify existing fish populations, and describe by self-sustaining or not.
Define and identify high potential spotted frog habitat and occupied habitat.
Define and identify traditional fishing areas/recreation hubs.
Evaluate connectedness of habitats for fish and frog populations to map potential sources
and sinks.
6. Define and identify Spotted Frog Conservation Areas, where priority will be given to
maintain or enhance this species through conservation actions.
7. Develop Conservation Area management strategies for Conservation Area(s).
X.
MONITORING STRATEGY
Summary Research/Monitoring
The USFS, in cooperation with the USFWS and U.S. Geological Survey, began investigating the
Penn Lake population in 1997. The objectives of the 1997 study were to “gather preliminary
spatial distribution information and reassess demographic patterns of the population,” (Pearl
1997).
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Conservation Agreement cont.
The study expanded in 1998 to include examination of 3 non-wilderness potential sites on the
WNF for spotted frogs (no frogs were found); exploration of potential spotted frog habitats and
characterization of occupied site habitat in the Mink lake Basin and surrounding Three Sisters
Wilderness Areas; and provision of a qualitative assessment of threats to the Mink Lake Basin
populations (Pearl 1998).
In 1999, the study again expanded to develop a better understanding of spotted frog distribution
and status in the adjacent upper Cultus drainage on the Deschutes NF. We also collected water
level and temperature information in rearing habitat and probable over-wintering habitats near
Penn Lake. In 1998 and 1999, a survey method was refined to assess spotted frog abundance as
well as a suite of physical habitat variables. Over 50 individual frogs were uniquely marked
during this time period (Pearl 1999).
The study continues in 2000 with the addition of an expanded investigation of the spotted frog
autecology at Penn Lake complex. PIT tagged individuals will provide information on
movement patterns at montane sites. A subset of frogs will be toe-clipped for examination of
skeleto-chronology and size-age relationships.
Understanding the opportunity to eradicate brook trout from these occupied spotted frog habitats,
in partnership with ODFW, has also been a focus in 1999, continuing in 2000. Installation of gill
nets is testing efficacy of removal (Pearl and Bury 2000).
Minimum Future Monitoring Recommendations
The continued recovery of the Penn Lake Complex population should be monitored every other
year using the protocols developed by Pearl (1997-1999). Findings will be reviewed as soon as
practicable after field season by the Conservation Agreement partner groups. The USFS will
take responsibility for ensuring that this work is a high priority for funding on the Forest.
If monitoring indicates that the population is suffering a severe decline (“severe” to be defined
by the Conservation Agreement partner groups), this Agreement will be reviewed by the partner
groups for its adequacy in providing for recovery of this population.
XI.
SIGNATURES -- July 26, 2000
USFWS_____________________________________________________________________
Kemper McMaster, State Supervisor
USFS_______________________________________________________________________
Darrel Kenops, Willamette National Forest Supervisor
ODFW______________________________________________________________________
Chris Wheaton, Regional Director
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