In Cooperation with U.S. Environmental Protection Agency 

Experimental Repatriation of Mountain Yellow-legged 

Frogs (Rana muscosa) in the Sierra Nevada of California 

By Gary M. Fellers, David F. Bradford, David Pratt, and Leslie Wood

Open-File Report 2008–1144 

U.S. Department of the Interior 

U.S. Geological Survey 

Western Ecological Research Center 
U.S. Department of the Interior 

DIRK KEMPTHORNE, Secretary 

U.S. Geological Survey 

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia 2008 

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Suggested reference: 

Fellers, Gary, Bradford, David, Pratt, David, and Wood, Leslie 2008, Experimental Repatriation of Mountain 

Yellow-legged Frogs (Rana muscosa) in the Sierra Nevada of California: U.S. Geological Survey Open-File 

Report 2008–1144, 58 p. Available at http://pubs.usgs.gov/of/2008/1144/ 

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Contents 

Abstract................................................................................................................................................................................1

METHODS ............................................................................................................................................................................3

Study Animal....................................................................................................................................................................3

Tableland Release Sites ................................................................................................................................................3

Sixty Lake Basin Donor Area ....................................................................................................................................4

Life History Stages and Definitions .............................................................................................................................4

Capture, Handling, and Transportation.......................................................................................................................4

1994................................................................................................................................................................................4

1995................................................................................................................................................................................5

Release of Repatriated Rana muscosa at the Tableland Sites ..............................................................................5

1994................................................................................................................................................................................5

1995................................................................................................................................................................................6

Rana muscosa Monitoring............................................................................................................................................6

Predator Surveys ............................................................................................................................................................6

pH and Electrical Conductivity .....................................................................................................................................6

Water Temperature........................................................................................................................................................7

Weather Data ..................................................................................................................................................................7

Pesticides.........................................................................................................................................................................7

Statistical Analysis .........................................................................................................................................................7

RESULTS...............................................................................................................................................................................8

Survival during Collection, Holding, Transport, and Release .................................................................................8

Eggs ...............................................................................................................................................................................8

Tadpoles .......................................................................................................................................................................8

Subadults......................................................................................................................................................................8

Adults ............................................................................................................................................................................8

Long-Term Survival of Tadpoles and Subadults .......................................................................................................8

1994................................................................................................................................................................................8

1995................................................................................................................................................................................9

1996-1998 Surveys for Tadpoles and Subadults........................................................................................................9

Long-Term Survival of Adults .......................................................................................................................................9

Frogs released in 1994................................................................................................................................................9

Frogs released in 1995..............................................................................................................................................10

Recruitment of Adult Rana muscosa at the Tableland ..........................................................................................10

Dispersal from Release Sites .....................................................................................................................................10

Growth of Adult Frogs ..................................................................................................................................................11

Predation........................................................................................................................................................................11

Water Temperature......................................................................................................................................................12

pH and Electrical Conductivity ...................................................................................................................................12

Pesticides.......................................................................................................................................................................13

DISCUSSION......................................................................................................................................................................13

Repatriation Techniques .............................................................................................................................................13

Survival of Repatriated Rana muscosa.....................................................................................................................13

Possible Causes for the Loss of Rana muscosa .....................................................................................................14

i 
Weather Patterns......................................................................................................................................................15

Water Quality.............................................................................................................................................................15

Predators....................................................................................................................................................................16

Dispersal.....................................................................................................................................................................16

Disease .......................................................................................................................................................................17

Pesticides...................................................................................................................................................................17

CONCLUSIONS..................................................................................................................................................................18

ACKNOWLEDGMENTS ....................................................................................................................................................19

References Cited ..............................................................................................................................................................19

Tables 

1. Historic records of Rana muscosa at the four Tableland area release sites at Sequoia National Park, 

CA (Bradford, unpub. data). The absence or very low numbers of adult frogs in 1978 at Frog 

Lake, Far Pond, and Full Moon Pond represented a dramatic decline from the previous year 

(Bradford 1983) ....................................................................................................................................................23

2. Rana muscosa repatriated in 1994 from Sixty Lake Basin (Kings Canyon National Park) to the 

Tableland sites (Sequoia National Park, CA).................................................................................................24

3. Rana muscosa repatriated in 1995 from Sixty Lake Basin (Kings Canyon National Park) to the 

Tableland sites (Sequoia National Park, CA).................................................................................................25

5. Counts of Rana muscosa at the Full Moon Pond release site in the Tableland area (Sequoia National 

Park) in 1996-1998. Definitions as in Table 4. ...............................................................................................27

6. Counts of Rana muscosa at the Frog Lake release site in the Tableland area (Sequoia National Park) 

in 1996-1998. Definitions as in Table 4............................................................................................................28

7. Survival of PIT-tagged adult Rana muscosa released in 1994 at Far Pond and Full Moon Pond. Dates 

of the first and last surveys in 1995 were August 23 and October 19; dates for 1996 and 1997 are 

provided in Tables 4 and 5.................................................................................................................................29

8. Survival of PIT-tagged adult Rana muscosa released in 1995 at three sites in the Tableland area. 

Dates of the first and last surveys in 1995 were August 27 and October 17 - 20, dates for 1996 

and 1997 are provided in Tables 4 and 5.........................................................................................................30

9. Weight and snout-vent length of Rana muscosa when first captured at Sixty Lake Basin (Kings 

Canyon National Park) donor site. The ratio represents weight/length3

. ................................................31

10. Adult Rana muscosa weight and snout-vent length (SVL) gains at each of the three Tableland 

release sites in 1995. Frogs were originally captured, tagged, weighed, and measured at Sixty 

Lake Basin on August 25, 1995, repatriated to the Tableland area the next day, and recaptured 

on September 20, 1995. Numbers are means ± one standard deviation. ................................................32

11. Number of western terrestrial garter snakes (Thamnophis elegans) observed, captured, and 

containing frog remains at the Tableland sites in 1994 and 1995. Rana muscosa and Pseudacris 

regilla are both frogs (mountain yellow-legged frog, Pacific treefrog). ...................................................33

12. Concentration of pesticides (ng/g wet wt) in Rana muscosa tissue collected at the Tableland 

(Sequoia National Park, n = 20), and the Sixty Lakes Basin (Kings Canyon National Park, n = 20) 

California, USA, 18 - 22 August 1997 (from Fellers et al. 2004)....................................................................34

ii 
iii 

13. Concentration of pesticides (ng/liter) in surface water samples collected at the Tableland (Sequoia 

National Park) and the Sixty Lakes Basin (Kings Canyon National Park), California, 18 - 22 August 

1997 (from Fellers et al. 2004). Log Kow is an indicator of the degree to which a substance will 

bioaccumulate. Far Pond is referred to as G-049 in the table below. ......................................................35

Figures 

1. Location of the four Rana muscosa release sites in the Tableland area of Sequoia National Park, 

California ..............................................................................................................................................................36

2. Counts of Rana muscosa at Far Pond and the adjacent dispersal ponds, Sequoia National Park, 

in 1994....................................................................................................................................................................37

3. Counts of Rana muscosa at Full Moon Pond and the adjacent dispersal ponds, Sequoia National 

Park, in 1994 .........................................................................................................................................................38

4. Counts of Rana muscosa at Frog Lake and the adjacent dispersal ponds, Sequoia National Park, 

in 1994....................................................................................................................................................................39

5. Counts of Rana muscosa at Table Meadow and the adjacent dispersal ponds, Sequoia National 

Park, in 1994 .........................................................................................................................................................40

6. Counts of Rana muscosa at Far Pond and the adjacent dispersal ponds, Sequoia National Park, 

in 1995....................................................................................................................................................................41

7. Counts of Rana muscosa at Full Moon Pond and the adjacent dispersal ponds, Sequoia National 

Park, in 1995 .........................................................................................................................................................42

8. Counts of Rana muscosa at Frog Lake and the adjacent dispersal ponds, Sequoia National Park, 

in 1995....................................................................................................................................................................43

9. Dispersal of Rana muscosa from Far Pond, Sequoia National Park..................................................................44

10. Dispersal of Rana muscosa from Full Moon Pond, Sequoia National Park....................................................45

11. Dispersal of Rana muscosa from Frog Lake, Sequoia National Park ..............................................................46

12. Frog 1760 weight (g) before and after repatriation from Sixty Lake Basin, Kings Canyon National 

Park, to Far Pond, Sequoia National Park ......................................................................................................47

13. Frog 3173 weights (g) before and after repatriation from Sixty Lake Basin to Far Pond. Frog was 

a male; SVL 5.0 cm when captured at Sixty Lake Basin on August 25, 1995............................................48

14. Water Temperatures at Far Pond, Sequoia National Park, 1994-1995.............................................................49

15. Far Pond, Sequoia National Park, temperature at the surface and on the bottom at the deepest 

point, September 26, 1995 to August 21, 1996 ................................................................................................50

16. Full Moon Pond, Sequoia National Park, temperature at the surface and on the bottom at the 

deepest point, September 26, 1995 to August 21, 1996 ................................................................................51

17. Frog Lake, Sequoia National Park, temperature at the surface and on the bottom at the deepest 

point, September 26, 1995 to August 21, 1996 ................................................................................................52

18. pH values during 1994 at the four Tableland release sites, Sequoia National Park .....................................53

19. pH values during 1995 at the four Tableland release sites, Sequoia National Park .....................................54

20. Electrical conductivity values during 1994 at the four Tableland release sites, Sequoia National Park..55

21. Electrical conductivity values during 1995 at the four Tableland release sites, Sequoia National Park..56

22. Departures from long-term average daily temperature and precipitation for 1993 - 1994 (measured 

at Grant Grove, CA, 32 km NW of the Tablelands) ........................................................................................57

23. Departures from long-term average daily temperature and precipitation for 1994 - 1995 (measured 

at Grant Grove, CA, 32 km NW of the Tablelands) ........................................................................................58
Experimental Repatriation of Mountain Yellowlegged Frogs (Rana muscosa) in the Sierra Nevada of 

California 

By Gary M. Fellers, David F. Bradford, David Pratt, and Leslie Wood

Abstract 

In the late 1970s, Rana muscosa (mountain yellow-legged frog) was common in the 

Tableland area of Sequoia National Park, California where it was possible to find hundreds of 

tadpoles and adults around many of the ponds and lakes. Surveys in 1993-1995 demonstrated that 

R. muscosa was absent from more than half of all suitable habitat within the park, including the 

Tableland area. At that same time, R. muscosa was still common at Sixty Lake Basin, Kings 

Canyon National Park, 30 km to the northeast. To evaluate the potential causes for the extirpation, 

we repatriated R. muscosa eggs, tadpoles, subadults, and adult frogs from Sixty Lake Basin to four 

sites in the Tableland area in 1994 and 1995. We subsequently surveyed each release site and the 

surrounding area 2 - 3 times per week in 1994-1995, and intermittently in 1996-1997, to monitor 

the survival of all life history stages, and to detect dispersal of adults and subadults. We also 

monitored predation, water quality, weather, and water temperature. 

Our techniques for capturing, holding, transporting, and releasing R. muscosa were refined 

during the study, and during 1995 resulted in high initial survival rates of all life history stages. 

Adult frogs were anaesthetized, weighed, measured, tagged, and held in plastic boxes with wet 

paper towels. Tadpoles were collected and held in fiberglass screen cages set in the water at the 

edge of a pond. This resulted in relatively natural conditions with less crowding and good water 

circulation. Frogs, tadpoles, and eggs were placed in Ziploc bags for transport to the Tableland by 

helicopter. Short-term survival of tadpoles, subadults, and adults was high at all four release sites, 

tadpoles reached metamorphosis, and adult frogs were still present. However, we detected no 

evidence of reproduction at three sites (e.g., no new eggs or small tadpoles) and nearly all life 

history stages disappeared within 12 months. At the fourth site, there was limited reproduction, but 

it was insufficient to maintain a population. 

It appears that the causal factors for the demise of R. muscosa in the Tableland during the 

1970s were still operating in the 1990s or that a new limiting factor has developed. Dispersal, 

weather, water quality, and predation do not appear to be causative agents; since fish have never 

been present in the portions of the watershed where we were working, they were not a factor. 

Observations and data are consistent with the hypotheses that chytridiomycosis, caused by the 

chytrid fungus Batrachochytrium dendrobatidis, and/or exposure to airborne pesticides caused both 

declines. However, at the time of our study, chytridiomycosis had not been described and the 

potentially significant role of contaminants was largely undocumented. 

1 
Amphibians are declining in many areas around the world (Lips, 1999; Houlahan et al., 

2000; Stuart et al., 2004). In the western United States, declines of frog, toad, and salamander 

populations have been widely reported and populations of several species appear to have been 

extirpated (Fellers and Drost, 1993; Drost and Fellers, 1996; Corn, 2000; Davidson et al., 2002). 

Healthy, seemingly well-protected populations have disappeared for no obvious reason. These 

losses are significant both because of the decline in biodiversity and also because amphibians are 

believed to be sensitive biological indicators of the health of the environment (Blaustein and Wake, 

1990). 

The causes of amphibian population declines are largely unknown, but several human and 

natural factors have been suggested, including land use changes, non-native predators and 

competitors, acidic waters, pesticides, long-term fire suppression, increased UV-B radiation, and 

disease (Hayes and Jennings, 1986; Bradford, 1989, 1991; Bradford et al., 1992, 1994b; Berger et 

al., 1998; Corn et al., 1989; Fellers and Drost, 1993; Lips, 1999; Fellers et al., 2001; Sparling et al., 

2001; Stuart et al., 2004). Unfortunately, most of the declines have only been noted well after they 

occurred (but see Lips, 1999). One of the difficulties in identifying the cause(s) of declines is the 

lack of observations and/or experiments that coincided with the declines. In this study, we 

repatriated R. muscosa to the Tableland area so we could evaluate possible causes of decline. 

Rana muscosa is one of the frogs that have declined dramatically in the western United 

States. It is currently a candidate for listing as an endangered species under the Endangered 

Species Act (USFWS, 2003), but the USFWS (2007) has determined that formal listing is 

"warranted but precluded." This frog was once abundant throughout much of the Sierra Nevada 

(Grinnell and Storer, 1924) and was common around mountain lakes, ponds, and meadow streams 

in the southern Sierra Nevada as recently as the 1970s (Bradford et al., 1994a). One of the authors 

(DB) conducted extensive field work on R. muscosa in Sequoia National Park from 1978 to 1980. 

At that time, it was possible to find hundreds of tadpoles and scores of adults around many of the 

ponds and lakes in the park (Bradford; 1983, 1991). 

By the mid-1990s, R. muscosa populations had exhibited conspicuous declines throughout 

the southern Sierra Nevada. Surveys of 670 sites in Sequoia and Kings Canyon National Parks 

from 1993 to 1995 indicated that R. muscosa was apparently gone from more than half of suitable 

habitat (Fellers, unpub. data), including the study sites where the species was abundant in the late 

1970s (Bradford et al., 1994a). There were, however, some areas where R. muscosa was still 

common, most notably at Sixty Lake Basin in Kings Canyon National Park, where large 

populations were present throughout our study (1993-1995; Fellers, unpub. data). 

Land managers are increasingly interested in repatriations as a tool for preserving 

amphibian populations. Unfortunately, there are almost no useful data to guide decisions with 

respect to repatriations of declining amphibians, e.g., how to carry them out, how refugia can be 

established and protected, and how to mitigate causative factors (see review by Lind, 2004). 

Dodd and Siegel (1991) and Dodd (2005) point out that programs to reestablish amphibian 

populations are often flawed by not investigating the causes for the original decline or extirpation. 

We designed our study to address this concern. Specifically, we wanted to evaluate the factors that 

might contribute to the decline of R. muscosa. Our goal was not to reestablish a viable population 

of R. muscosa. We expected that whatever caused the original loss would still be present, and that 

the repatriated frogs would likely decline. We conducted this study to recreate the conditions 

surrounding the loss of R. muscosa so we could evaluate causes of decline. We gathered data on 

growth, survival, dispersal, weather, water quality, predation, and contaminants along with data on 

survival of all life history stages, and reproductive effort (e.g. presence of new egg masses). Unlike 

most areas within the range of R. muscosa in the Sierra Nevada, the repatriation site never had fish 

in the upper portions of the watershed where our study took place, so fish were not a factor. 

2 
Unfortunately, our study was carried out several years prior to the description of chytridiomycosis 

in amphibians (Berger et al. 1998), and before pesticide drift from the Central Valley of California 

had been recognized as a potentially significant problem for Sierra Nevada amphibians (Sparling et 

al., 2001), so we never examined frogs or tadpoles for chytridiomycosis and only looked at 

pesticides as the repatriated frogs were dying off (Fellers et al., 2004). 

METHODS 

Study Animal 

Rana muscosa breeds in high mountain ponds, lakes, and some streams in the Sierra Nevada 

at elevations from approximately 1500 - 3700 m (Zweifel, 1955). Eggs are laid immediately after 

snowmelt and tadpoles typically do not metamorphose until their third summer (Vredenburg et al., 

2005). During mid-summer, nominal tadpole age classes are readily distinguished. First-year 

tadpoles are relatively small (< 40 mm total length), second-year tadpoles are appreciably larger 

with minute hind limbs (Gosner stage < 36; Gosner, 1960), and third-year tadpoles have 

conspicuous hind limbs (Gosner stage > 36). Adults probably mature and begin breeding after 

three or four years (Vredenburg at al., 2005). At our study areas, male R. muscosa develop 

secondary sexual characteristics when they reach approximately 4.5 cm snout-vent length, and 

weigh about 10 g. We refer to frogs > 4.5 cm as adults, and frogs less than that size as subadults. 

Tableland Release Sites 

We selected the Tableland area of Sequoia National Park (36° 37’ 05” N; 118° 38’ 16” W; 

Fig. 1) because of 1) the absence of R. muscosa in 1993; 2) the existence of several, large 

populations of R. muscosa within the previous 20 years; 3) availability of historic data on 

population size; 4) lack of non-native predators (e.g., trout); and 5) isolation from any extant 

populations of R. muscosa that could disperse into the study area. 

During the 1970s, the Tableland area supported many hundreds of adult and larval R. 

muscosa at a minimum of 17 sites within a 15 km2

 area (Bradford, 1991; Bradford et al., 1994a). 

Population declines were first noted in the late 1970s (Table 1), and the last R. muscosa was seen in 

the Tableland area during an extensive survey there in 1989 (Bradford et al., 1994b). In 1993, 

Bradford and Fellers spent a week surveying all suitable frog habitat within the Tableland and 

found no R. muscosa, either in that watershed or in the upper reaches of the adjacent watersheds. 

Since it is relatively easy to detect adults and tadpoles in the clear, nearly vegetation-free ponds and 

lakes of the high Sierra, it is unlikely that we overlooked extant populations during repeated 

surveys prior to the experimental repatriation. 

Unlike many places in the Sierra Nevada, the Tableland area was largely devoid of fish. 

Introduced fish were present in two nearby lakes (Moose Lake and Pear Lake), but only one lake 

upstream from these lakes or upstream from streams draining these lakes has ever had fish (1.0 km 

from Far Pond). Hence, fish did not appear to play a role in the decline of R. muscosa in the 

Tableland area, and fish were not a complicating factor for our study. 

Migration of R. muscosa to and from the Tableland area during our study was unlikely. 

Non-native, predaceous trout inhabited all the streams in surrounding watersheds and at lower 

elevations in the Tableland watershed. Thus the streams could not easily serve as recolonization or 

dispersal corridors for R. muscosa. Non-native trout are known to eliminate R. muscosa

populations where the two occur together (Bradford, 1989; Knapp and Matthews, 2000), and fish 

feed on both larvae (pers. obs.) and adults (Needham and Vestal, 1939). The nearest known R. 

3 
muscosa population was more than 10 km away, much greater than the 1 km that R. muscosa

occasionally move (Vredenburg et al., 2005). 

Rana muscosa were released at four sites (Fig. 1). Table Meadow is a 4.5 ha meadow 

(3,110 m elevation) with a stream running through it. Frog Lake is a small lake (2 ha, 4.1 m 

maximum depth, 3,080 m) that lies 250 m southwest of Table Meadow. In the late 1970s, it 

supported a large population of R. muscosa. Far Pond (1 ha, 2.7 m maximum depth, 3,290 m) is 

one of a chain of ponds at the head of a small drainage. Full Moon Pond (1 ha, 2.6 m maximum 

depth, 3,230 m) is also at the head of a small drainage. Rana muscosa populations existed at all 

four of these sites in the late 1970s. Frog Lake and Far Pond were referred to as sites G-013 and G049 by Fellers et al. (2004). The third pond downstream from Far Pond was referred to as G-054 

by these authors, whereas we have designated it Dispersal Pond 3. 

Sixty Lake Basin Donor Area 

Criteria for selecting the donor area were 1) a large population of apparently healthy R. 

muscosa; 2) elevation within 150 m (500 ft) of the release sites; 3) proximity to the Tableland area; 

and 4) a genetically diverse group of donor populations. Sixty Lake Basin in Kings Canyon 

National Park (36° 48’ 35” N; 118° 25’ 29” W) was selected as the donor area. The basin was one 

of the closest areas to the release sites (30 km) that still supported substantial populations of R. 

muscosa. During 1993-1994 surveys, we found 1,718 adult frogs, 1,289 subadults, and 16,027 

larvae at 65 sites within the basin. We limited the impact on donor populations by collecting only 

from the largest populations, and by not removing more than 20% of any life history stage, i.e. egg, 

tadpole, subadult, or adult. Typically, the removal was < 5% of any one stage. The donor site 

elevations (3,250 - 3,345 m; 10,660 - 10,975 ft) were similar to that of the Tableland release sites 

[3,080 - 3,290 m (10,105 - 10,794 ft)]. The area had also been identified as having one of the most 

genetically diverse populations of R. muscosa in the southern Sierra Nevada, based on 

mitochondrial DNA analysis (H. Bradley Shaffer and Gary M. Fellers, unpub. data). 

Life History Stages and Definitions 

Rana muscosa breed in high mountain ponds, lakes, and occasionally streams in the Sierra 

Nevada at elevations from approximately 1,500 - 3,700 m (4,900 - 12,150 ft) (Zweifel, 1955). 

Eggs are laid immediately upon snowmelt, sometimes while there is still ice around the edges of 

ponds. Tadpoles typically metamorphose during their third summer. At the highest elevations, it 

may take four summers (Vredenburg at al., 2005), and at the lowest elevations, tadpoles 

metamorphose after only one summer (Storer, 1925). During mid-summer, nominal age classes are 

readily distinguishable. 

Capture, Handling, and Transportation 

1994 

On June 11 - 14, eight egg masses, 468 second-year tadpoles, 624 third-year tadpoles, and 

97 subadult frogs were collected from nine ponds at Sixty Lake Basin. The number of tadpoles 

subsequently released was almost 40% lower due to mortality during the 1- 3 day holding period. 

We did not segregate frogs and tadpoles based on where they were collected. Subadult frogs were 

placed in plastic boxes (Rubbermaid, Wooster, OH; 29 x 18 x 7 cm) with six, 5.0 mm holes drilled 

in the lids to allow air circulation. Frogs (four per container) were kept moist with wet paper 

towels, which were changed once or twice a day as they became soiled. Eggs and tadpoles were 

4 
held in 4 L plastic freezer bags (Ziploc, Racine, WI) that were not sealed shut. Bags were held 

upright by placing them (in sets of four) in 40 x 28 x 23 cm plastic containers without lids. 

Tadpole densities were approximately 25 per bag. Each egg mass was placed in its own bag. 

Water was changed every 1 - 2 hrs throughout the day and 3 - 4 times during the night. On June 

14, the Ziploc bags were closed and all life stages were flown to the release sites by helicopter. 

On September 15 - 16, 50 adult frogs (25 males and 25 females) were collected from five 

ponds at Sixty Lake Basin. They were held as described above for subadults. On September 16, 

the frogs were backpacked 18 km (11 mi) to the nearest trailhead, and driven to the west side of the 

range, where each frog was anaesthetized with 0.02% benzocaine (Fellers and Freel, 1995), 

measured (snout-vent length), weighed (to nearest 0.1 g), and marked with a PIT tag. PIT tags 

were inserted under the skin just posterior to the skull. Once the tag was inserted, it was 

manipulated externally so it rested over the pelvic girdle. The frogs were then backpacked 13 km 

(8 mi) into the Tableland where they were released on September 20. 

 1995 

On August 24 and 25, 93 adult frogs (46 males and 47 females), 286 second-year tadpoles, 

and 324 third-year tadpoles (but no eggs or subadults) were collected at Sixty Lake Basin. Adult 

frogs were anaesthetized, weighed, measured, PIT-tagged, and held in Rubbermaid boxes with wet 

paper towels using the same techniques as in 1994. Unlike 1994, tadpoles were collected and put 

into fiberglass screen cages set in the water at the edge of a pond. This resulted in relatively natural 

conditions with less crowding and better water circulation compared with 1994. On August 26, 

they were transferred to 4 L Ziploc bags for about 45 min during transport to the Tableland by 

helicopter.

Release of Repatriated Rana muscosa at the Tableland Sites 

1994 

All life history stages were released at the Tableland sites in 1994 (Table 2). The release 

procedure was designed to facilitate acclimation to the new environment. About 10% of the water 

was poured out of the container every 5-10 min, and a similar amount of fresh pond water was 

added back in so that eggs and tadpoles could adjust to differences in water temperature and 

chemistry. In 1994, amphibians at Table Meadow, Frog Lake, and Full Moon Pond were released 

after an hour into a 2 x 1.5 x 1 m (L x W x H) temporary holding cage made of fiberglass screen 

supported by PVC pipe. The fiberglass and pipe had been washed with Downy soap (Procter and 

Gamble, Cincinnati, OH) and thoroughly rinsed to remove any manufacturing residue. The release 

cage was set at the edge of the pond so that one end was almost submerged and the other end was 

resting on the shore. This provided conditions suitable for both the aquatic and terrestrial stages. A 

head of crushed lettuce was added to each cage as a food supplement, since the normal complement 

of algae and phytoplankton might not have been readily available inside the cages. After two days, 

the cages were opened and all amphibians were allowed to swim freely into the pond. 

At Far Pond (3,290 m), the pond was still 80% frozen during the day, and both darkness and 

refreezing of the pond at dusk prevented use of a holding cage. It was necessary to break the ice 

and release the eggs, tadpoles and subadult frogs directly into the pond after an hour acclimation as 

described above. 

5 
1995 

Second-year, third-year, and adult frogs were released at three of the four Tableland sites in 

1995 (Table 3). As in 1994, frogs and tadpoles were held temporarily in fiberglass screen cages at 

the edge of the pond, but this time they were released into the pond after only a few hours. 

Rana muscosa Monitoring 

In both 1994 and 1995, R. muscosa at the Tableland release sites were monitored every 1- 3 

days throughout the summer. In 1994, monitoring occurred from the initial release on 14 June, and 

continuing until the onset of heavy snowfall on September 27. In 1995, monitoring extended from 

the time that ice melted from the lowest elevation site (August 1) until October 20, when ice was 

forming nightly on the higher elevation ponds. The sites were also monitored at approximately 

monthly intervals during the ice-free summers of 1996 and 1997, and during a single visit in 

September 1998. 

Monitoring consisted of counting all life history stages while 1) walking the perimeter of 

each pond and the length of each bank of Table Meadow stream during the day, and 2) sweeping a 

dip net through the rather limited vegetation in or near the water to make frogs and tadpoles move 

and become more conspicuous. After adult frogs were released at the Tableland sites (September 

20, 1994), monitoring was extended to include connecting streams and ponds within several 

hundred meters of all four release sites to evaluate dispersal. In 1995, adult frogs were caught at 

two-week intervals, scanned for PIT tags, weighed, measured, and examined for signs of disease or 

injuries. Frogs were also captured and examined in a similar fashion during surveys in 1996 - 

1998. 

Predator Surveys 

At least once each week during the 1994 and 1995 field seasons, we surveyed each of the 

release sites for potential R. muscosa predators; the behaviors of possible predators were recorded, 

e.g., foraging in the water, foraging on land, flying, swimming, resting, passing through, fleeing, 

drinking, bathing, or other. Western terrestrial garter snakes (Thamnophis elegans) were captured 

when possible and palpated to determine if they had a food bolus. If a bolus was found, the snake 

was gently encouraged to regurgitate it so we could see whether the snake had fed on tadpoles, 

subadults, or adult frogs of either R. muscosa or Pseudacris regilla (Pacific treefrog) (Filippi et al., 

2005). Garter snakes captured after mid-July 1994 were marked by clipping ventral scales with 

fine-tipped scissors. No other species of snake was seen during our study. 

pH and Electrical Conductivity 

At approximately one-week intervals throughout the summers of 1994 and 1995, we 

measured pH and electrical conductivity (EC) at all four release sites. The samples were collected 

from just below the water surface, using clean, rinsed, high-density polypropylene bottles. All 

samples were analyzed at our Tableland base camp, using battery-powered equipment. We 

calibrated the equipment prior to each use. The pH meter (Accumet, model 1001; Fisher Scientific, 

Los Angeles, CA) was calibrated with pH 4.0, 7.0, and 10.0 standards. The electrical conductivity 

meter (Hach Mini Conductivity Meter, model 17250; Hatch, Loveland, CO; www.hach.com) was 

calibrated with a 9.8 μS/cm standard. 

6 
Water Temperature 

Water temperature was recorded hourly with data loggers (StowAway; Onset, Pocasset, 

MA). On August 5, 1994, two temperature loggers were deployed in Far Pond at depths of 0.5 and 

1.0 m above the bottom, at a time when the water level was slightly more than a meter deep at that 

part of the pond. The data loggers were retrieved on August 23, 1995. The data loggers remained 

at 0.5 and 1.0 m above the bottom, but the water level in the pond had increased by about one 

meter. 

From September 26, 1995 to August 21, 1996, we monitored water temperature at Full 

Moon Pond, Frog Lake, and Far Pond. At each pond, a pair of temperature loggers was deployed. 

One logger was weighted and lowered to the bottom in the deepest part of the pond. The other 

logger floated on the surface, connected by a nylon cord. The cord served to anchor the surface 

logger and to facilitate retrieval of the bottom logger. 

Weather Data 

Long-term weather data were obtained from the National Weather Service weather station 

at Grant Grove, California (36o 44’ 21” N; 118o 57’ 51” W), 32 km NW of the Tableland at an 

elevation of 1990 m (6,530 ft). This was the closest weather station with relatively complete longterm weather data. Data have been collected since November 1, 1940 and were obtained from the 

National Climatic Data Center (www.ncdc.noaa.gov). 

Pesticides 

On August 18 - 20, 1997, we were able to find only 20 R. muscosa in the Tableland area. 

All 20 frogs were collected, including 12 adult males, three adult females, and five subadults. 

Sixteen of the frogs were collected at Far Pond. Two frogs were collected at Dispersal Pond 3 (Fig. 

9), and one was collected at Frog Lake. Each frog was anaesthetized in a 0.02% solution of 

benzocaine (Fellers and Freel, 1995), weighed, measured, and frozen in liquid nitrogen. 

On August 22, 1997, 20 R. muscosa from Sixty Lake Basin donor sites were collected (10 

adult males, 5 adult females, and 5 subadults) and similarly processed. Frogs came from two 

unnamed ponds described in Fellers et al. (2004). Frog samples were shipped on dry ice to the 

University of Nevada (Reno, NV) for processing. Tissue samples were analyzed for 

organophosphate insecticides, endosulfans, chlordanes, hexachlorocyclohexanes, and DDTs at the 

U.S. Department of Agriculture in Beltsville (MD). Methodological details are provided by Fellers 

et al. (2004). 

At two ponds in the Tableland and two in Sixty Lake Basin, concurrent 4-liter water 

samples were also collected. Water was filtered through a glass fiber filter and extracted using a 4-

g C18 solid-phase extraction cartridge [see LeNoir et al. (1999) for detailed description of the 

sample collection, processing, and analysis methods]. Water samples were analyzed for trifluralin, 

chlorpyrifos, chlorpyrifos oxon, chlorothalonil, endosulfan I and II, malathion, and diazinon. A 

detailed description of the sample collection, processing, and analytical methods has been 

published by LeNoir et al. (1999). 

Statistical Analysis 

Data were analyzed using Statistix (version 8.0, Analytical Software, Tallahassee, FL, USA). 

Mann-Whitney and Wilcoxon paired sample non-parametric tests were used because our data were 

not normally distributed. We used P = 0.05 to evaluate statistical significance. Measures of 

variability are given as standard deviations. 

7 
RESULTS 

Eight egg masses, 1264 tadpoles, 97 subadults, and 143 adult frogs were released at the 

Tableland (Tables 2 - 3). 

Survival during Collection, Holding, Transport, and Release 

Eggs 

 All eight egg masses appeared to survive in good condition from time of collection until 

they were released. After release, some masses drifted from their original positions because they 

were not attached to vegetation, as they normally would be. A substantial buildup of pine pollen 

along the edge of the release ponds made it difficult to relocate egg masses. In spite of careful 

searches, we were unable to find two of the eight egg masses after one day, and could not find any 

of the egg masses after five days, hence we could not evaluate whether the eggs hatched. 

Tadpoles 

In 1994 there was almost 40% loss of tadpoles while holding them in Ziploc bags at Sixty 

Lake Basin prior to repatriation, probably due to crowding and/or lack of oxygen. The loss was 

primarily at night when the water was changed less frequently. Losses were greater for third-year 

than second-year tadpoles. In 1995, we used fiberglass screen holding cages placed at the edge of a 

pond, and tadpole survival was 100%. Survival of tadpoles during transport and release was >99% 

in both 1994 and 1995. 

Subadults 

 There was no subadult mortality during collecting, holding, or transport. Three subadults 

were lost, however, during the release at Far Pond. That release was carried out in the dark when 

the pond surface was refreezing. One subadult was stepped on, another was found frozen in the 

snow the next morning, and the third was found dead underwater two days later. These problems 

were largely caused by late arrival of the transport helicopter, resulting in the release taking place at 

dusk, much later in the day than planned. 

Adults 

 There was no mortality among the adult frogs repatriated from Sixty Lake Basin to the 

Tableland in either 1994, when they were transported overland for four days, or in 1995 when they 

were transported by helicopter. 

Long-Term Survival of Tadpoles and Subadults 

1994 

We conducted more than 30 surveys at each of the four Tableland sites in 1994 (Fig. 2 - 5). 

Several patterns were evident at all four sites. 1) Counts for all life stages varied considerably 

among surveys, even for surveys within a few days of each other. Some, but not all, of the low 

counts were on days with adverse weather, e.g., low air temperature, strong winds, or rain. 2) The 

number of subadults in late summer exceeded the number released in June, demonstrating that 

8 
some tadpoles successfully metamorphosed. 3) The number of tadpoles counted during early 

summer was usually well below the number actually present as shown by the number of subadults 

observed at the end of the season. Only a fraction of the repatriated tadpoles were observed at any 

one time, even within a few days of release. 4) Because tadpole counts were so low, it is not 

possible to determine if second-year tadpoles survived to their third summer. 5) Counts for both 

second- and third-year tadpoles declined to zero or very low numbers by late summer. 6) Tadpole 

and subadult counts were lowest at the Table Meadow site, where vegetation (especially willows, 

Salix sp.) hindered surveys. For this reason, subsequent releases were not done at Table Meadow. 

1995 

We conducted nine surveys at Table Meadow between August 1 and October 17, 1995, but 

no frogs, tadpoles, or eggs were found. We conducted 17 - 20 surveys at the three Tableland sites 

where tadpoles and adult frogs (i.e. no eggs, no subadults) were released in August 1995 (Fig. 6 - 

8). As in 1994, the survey counts were highly variable. Counts of subadults (which were released 

only in 1994) were substantially lower in 1995 than in 1994 at both Full Moon Pond (1994: median 

= 15, n = 32 counts versus 1995: median = 1.5, n = 20) and Frog Lake (1994: median =10, n = 32 

versus 1995: median = 0, n = 17), but were similar between years at Far Pond (1994: median = 

34.5, n = 20 counts versus 1995: median = 22, n = 37). The absence of subadults at Full Moon 

Pond and Frog Lake during the early part of the 1995 season, and low numbers of subadults later in 

the season, suggest that subadults did not survive from 1994 to 1995. In contrast, many of the 

subadults at Far Pond survived the winter of 1994-1995. Tadpole counts were zero or near zero at 

all three sites at the beginning of the 1995 season, consistent with counts at the end of the 1994 

season. First-year tadpoles were observed at only Far Pond. Three were found on 3 October, and 

four on 10 October. These tadpoles came from eggs oviposited at Far Pond in 1995. 

1996-1998 Surveys for Tadpoles and Subadults 

During 1996-1998, R. muscosa tadpoles were found at all three Tableland pond sites. 

Nearly all of these were third-year tadpoles (Table 4 - 6). The maximum counts in 1996 were 

substantially greater than counts at the end of 1995 (Fig. 6 - 8). The increase in tadpoles may have 

occurred in 1995 as well, but it would have been masked by the repatriation of additional tadpoles 

in 1995. 

No subadults were found at Full Moon Pond or Frog Lake in July 1996, suggesting that 

none survived from 1995 (Tables 5 - 6, Fig. 5). At Far Pond, the low subadult numbers in July 

1996 (compared to the number counted at the end of 1995) suggest that mortality was also high 

during the winter of 1995-1996 (Table 4, Fig. 6). Subsequent declines of second-year tadpoles, 

third-year tadpoles, and subadults at Far Pond during 1996-1998 indicate a loss due to 

metamorphosis and/or mortality, and little recruitment. The only documentation of reproduction 

during 1996-1998 was a single second-year tadpole found in Dispersal Pond 3 (Table 4, Fig. 9) in 

1998, three years after the last second-year tadpole had been released. 

Long-Term Survival of Adults 

Frogs released in 1994 

 At both Far Pond and Full Moon Pond, frog numbers rapidly declined to 2/3 of the number 

released (Table 7). By 1995, frog counts at the two ponds differed from each other greatly. At Full 

Moon Pond, none of the 25 repatriated frogs was ever seen after 1994. 

9 
At Far Pond, 15 of the 25 frogs released in 1994 were captured in 1995, seven of the 

original 25 in 1996, and three in 1997. 

Frogs released in 1995 

At Far Pond, all 31 of the adults were captured at least once during the 1995 season; 15 

were captured again in 1996, and two in 1997 (Table 8). At the other two sites, fewer frogs were 

captured in 1995 than at Far Pond, and only two of the repatriated frogs were found after 1995, 

both at Full Moon Pond at the start of 1996. 

Recruitment of Adult Rana muscosa at the Tableland 

Recruitment of adults from eggs, tadpoles, or subadults occurred only at Far Pond (Tables 4 

- 6) as shown by the presence of adult frogs lacking PIT tags. After 1995, we found only three of 

the repatriated adult frogs, one at Frog Lake, and two at Full Moon Pond. In contrast, untagged 

adult R. muscosa were found at Far Pond in both 1996 and 1997. We tagged a total of 28 frogs 

there, 14 adults and 4 subadults in 1996, and 10 adults in 1997. Some of the adult frogs found at 

Far Pond in 1996 and in 1997 were not captured (Table 4). Since none of the unmarked adults was 

found until 1996, it seems likely that they developed from tadpoles released at Far Pond, rather than 

from the 25 (untagged) subadults released there in June 1994. 

On July 15 - 17, 1997, all the frogs that we found appeared sick; two were found dead and 

three died within a day of being captured (Table 4). On August 19, 1997, all 20 frogs observed at 

our repatriation sites (15 adults, 5 subadults; 19 at or near Far Pond and one at Frog Lake) were 

collected for analysis of pesticides. Only one frog was observed during the 1998 survey. However, 

four adult frogs were found at Dispersal Pond 3 (near Far Pond, Fig. 9) in 2000, and one was found 

there in 2001 (Knapp, unpub. data). 

Dispersal from Release Sites 

All ponds and streams in the vicinity of the release sites were surveyed for frogs at the end 

of the 1994 field season, and at approximately two-week intervals throughout the 1995 field season. 

Far Pond was the site with the most suitable frog habitat in the immediate vicinity and we detected 

significantly more dispersal at Far Pond where 14 of the 56 released frogs (25%) were later found 

in nearby ponds, compared to 8 of 79 repatriated frogs (10%) at the other three sites combined (χ2

 = 

6.54, P = 0.0106). No appreciable difference was found in the dispersal frequency of males and 

females; of the 22 dispersing frogs, 12 were females and 10 were males. Maximum straight-line 

dispersal distance ranged from 50 m to 510 m, with a median of 80 m (mean = 173 ± 138 SD). 

Some frogs were detected at increasingly greater distances from their release site. Frog 

7112 was released at Far Pond on 20 September 1994; it was found in Dispersal Pond 1 (25 m from 

Far Pond) on 21 September 1995, and was found in Dispersal Pond 3 (90 m from Far Pond) on 3 

October 1996 (Fig. 9). Frog 6744 was released on 20 September 1994; it was found in Dispersal 

Pond 5 on 5 September 1995 and 10 October 1995, and in Dispersal Pond 6 on 19 October 1995 

(Fig. 9). The total distance from Far Pond to Dispersal Pond 6 (via the connecting stream) was ≥

800 m. 

Frog 7026 dispersed away from the release site and then returned. On 26 August 1995, frog 

7026 was released at Frog Lake; on 21 September 1995, it was > 200 m away in the stream flowing 

through Table Meadow (Fig. 10); on 5 October 1995, it was back in Frog Lake. 

Not all dispersal was closely associated with water; in a few cases, the dispersal was across 

land. The route from Full Moon Pond to the two ponds to the north (Fig. 11) traverses a rocky 

10 
slope and entailed a 30 m elevation gain over a distance of 500 m; at least 80% of the route was 

over land. 

Growth of Adult Frogs 

Adult frogs caught at Sixty Lake Basin donor area did not differ significantly in length 

between 1994 and 1995 [Snout-vent length (SVL) 5.6 vs. 5.5 cm], but they weighed significantly 

more in 1994 (18.5 vs. 14.7 g, Mann-Whitney U = 3545, n = 143, P < 0.001; Table 9). A 

comparison of weight/length3

 shows that the 1994 frogs had significantly (19%) higher values than 

1995 frogs (U = 3970, n = 143, P < 0.001). At the Tableland release sites in 1995, almost all frogs 

gained weight after repatriation. Average weight gain at the three release sites ranged from 22 to 

28%, with an average of 24% (Wilcoxon T = 1, n = 47, P < 0.001; Table 10). We recorded a 

similar, significant increase in length at all three sites combined (~2 mm; T = 32, n = 47, P < 0.001; 

Table 10). On 20 September 1995, the condition (weight/length3) of repatriated frogs had 

significantly increased (by 19%) since their original capture on 25 August 1995 (0.095 g/cm3

 versus 

0.085 g/cm3; T = 84, n = 47, P < 0.001). Changes in weight for two representative frogs, one 

repatriated to the Tablelands in 1994 (Fig. 12), and the other in 1995 (Fig. 13), show summer 

weight gain and winter weight loss, a pattern that was similar to other repatriated adult frogs. 

Predation 

During 1994 and 1995, we recorded 168 occurrences of potential R. muscosa predators at 

the four Tableland release sites. These included 92 observations of Brewer's blackbirds (Euphagus 

cyanocephalus), 39 of western terrestrial garter snakes, 23 of people (who might catch frogs), and 

four or fewer observations of each of the following: ravens (Corvus corax), eared grebes (Podiceps 

nigricollis), American dippers (Cinclus mexicanus), American kestrels (Falco sparverius), black 

bears (Ursus americanus), coyotes (Canis latrans), and alligator lizards (Elgaria sp.). The 

blackbirds were typically in groups of 10 or fewer. They often foraged both on land and in the 

shallow water, but the prey appeared to be insects. Despite hours of observation, we never saw 

them eating anything as large as a tadpole. 

Of the 32 captures of western terrestrial garter snakes, eight had recently eaten larval or 

subadult R. muscosa or P. regilla (Table 11). All 39 observations and all 32 captures of western 

terrestrial garter snakes were at the three Tableland sites where the repatriated R. muscosa 

disappeared most rapidly. None were at Far Pond, where R. muscosa persisted the longest. All but 

four of the garter snakes were observed in 1994. 

Amongst the birds, only the Eared Grebe seemed to have the potential to have an impact on 

R. muscosa since that species has been reported to eat both tadpoles and small frogs 

(http://www.houghtonmifflinbooks.com/peterson/resources/identifications/eagr/index.shtml#feedin

g; http://sdakotabirds.com/species/eared_grebe_info.htm). In 1995, a single eared grebe was seen 

at Full Moon Pond during three consecutive surveys (September 27 and 28, and October 4). It had 

not been there during any of the earlier surveys, (September 21 or before), nor was it there on 

October 11 or any subsequent survey in 1995. When present, the grebe remained in the center of 

the pond, where the water depths were 1 - 2 m at the time. We observed it with binoculars from a 

distance of approximately 30 meters. The water was clear, so that it was easy to see the grebe 

underwater. It repeatedly dove and swam in a meandering path along the bottom, typically for 

about 15 seconds, before it returned to the surface. It dove most frequently where the bottom was 

silt-covered rather than bare rock. While underwater, the grebe appeared to be moving continually, 

not obviously stopping to catch anything. During the three days that we encountered the grebe, we 

observed approximately 60 dives during an hour of watching. We could not determine whether the 

11 
grebe was feeding on tadpoles. We were certain that the grebe never went into the shallow water 

where the tadpoles were usually seen. Only once did the grebe appear to surface with something in 

its beak that might have been a frog or tadpole. On that occasion, the grebe dropped the object 

back into the water and did not pursue it. 

During and after the time the grebe was observed at Full Moon Pond in 1995, the counts of 

tadpoles, subadults, and adult frogs dropped to low levels and remained low (Fig. 7). Whether this 

was due to predation by the grebe was unclear since it could also have been due to reduced activity 

with the onset of cold weather in the fall. During a September 19, 1998 survey of Full Moon Pond, 

there was an eared grebe present, yet we found no R. muscosa. 

Water Temperature 

By early January 1995, water temperature at the Far Pond shallow data logger (1.0 m above 

the bottom) had cooled to a constant 0° C, indicating freezing to that depth (Fig. 14). By midJanuary, the deep data logger (0.5 m above the bottom) had also cooled to a constant 0° C. Both 

remained at zero until the unusually late thaw that began in August 1995. Unfortunately, since the 

data loggers were neither at the surface nor at the bottom of the deepest part of the pond, it was not 

possible determine when the surface froze or whether the pond froze to the bottom at its deepest 

point. 

Surface temperatures during the 1995-1996 winter at Far Pond, Full Moon Pond, and Frog 

Lake indicate that the ponds froze over between late-November and early-December, and remained 

frozen until late June to early July 1996 (Fig. 15 - 17). Data from the bottom data loggers showed 

that none of the three ponds froze to the bottom at their deepest points during that winter. The two 

shallower ponds (Full Moon Pond and Far Pond) cooled to less than 4° C. 

pH and Electrical Conductivity 

During 1994, pH varied little from week to week; most values were between 6.0 and 7.0 

(mean = 6.5 ± 0.4, range 5.7 - 7.8, n = 59; Fig. 18). We observed no seasonal trend (linear 

regression, R2

 = 0.0074, T = 1.15, P = 0.25). In 1995, pH ranged from 6.02 to 7.01 (mean = 6.5 ± 

0.3, n = 34; Fig. 19), and showed a slight rise through the summer. Conductivity (an indication of 

the quantity of dissolved electrolytes) was mostly between 2 and 10 μS/cm (mean = 5.2 ± 4.5, 

range 1.5 - 32, n = 93). Conductivity was significantly lower in 1995, a year of high precipitation 

(98 cm above normal), than in 1994, a year of low precipitation (34 cm below normal; National 

Weather Service, Grant Grove, CA) (T = 5.53, P < 0.001, n = 93). 

Conductivity values were lower in Far Pond and Full Moon Pond, at the tops of their 

watersheds (mean = 3.0, n = 46), than they were in Frog Lake and the Table Meadow stream (mean 

= 7.3, n = 47), farther down in their watersheds in 1994 - 95 (T = 6.6, P < 0.001; Fig. 20 - 21). 

Values increased during each summer as snowmelt runoff decreased. The highest values were 

found in the Table Meadow stream late in the 1994 season, when stream flow had almost stopped. 

Our measurements of electrical conductivity agree well with the observations of other 

researchers working a few kilometers downstream of our study sites, as well as measurements from 

elsewhere in the Sierra Nevada (Jim Sickman, pers. comm.). Electrical conductivity at the Marble 

Fork station in Sequoia National Park (downstream from three of the four Tableland sites) ranges 

from about 3 to 50 μS/cm. Sickman's data also demonstrate that larger snow packs lead to greater 

dilution, and lower electrical conductivity. 

12 
Pesticides 

Analysis of the frog tissues showed that dichlorodiphenyldichloroethylene (DDE) 

concentrations were 1 to 2 orders of magnitude higher than the other organochlorine compounds, 

and DDE concentrations for Tableland frogs were significantly higher than those for Sixty Lake 

Basin frogs (46 ± 20 ng/g wet wt at Tableland area, 17 ± 8 ng/g at Sixty Lake Basin; Table 12). 

Concentrations of γ-chlordane and trans-nonachlor were also significantly greater in Tableland frog 

tissues compared with Sixty Lake Basin. The organophosphate insecticides, chlorpyrifos, and 

diazinon, were observed primarily in surface water samples, with higher concentrations at the 

Tableland sites (Table 13). No contaminants were found at significantly higher concentrations in 

our Sixty Lakes samples. Further results and details are presented in LeNoir et al. (1999) and 

Fellers et al. (2004). 

DISCUSSION 

Repatriation Techniques 

Collecting all life history stages of R. muscosa was not difficult, in part because R. muscosa

were abundant at Sixty Lake Basin donor sites during our study. Holding R. muscosa prior to 

repatriation to the Tableland was a problem only for tadpoles (primarily third-year tadpoles) in 

1994. In 1995, we reduced tadpole mortality from 40% to zero by using screen holding cages 

placed at the edge of a pond. These cages allowed for the constant exchange of water, and tadpoles 

survived without mortality for up to two days. 

In both years that we repatriated tadpoles, we did so by helicopter. This was necessary for 

two reasons. First, the water required to hold the tadpoles weighed approximately 115 kg (254 lbs). 

Second, our experience in 1994 indicated that mortality was unacceptably high when tadpoles were 

kept in plastic bags for an extended period. By contrast, we successfully moved 50 adult R. 

muscosa by backpack, then by vehicle, then again by backpack, over a four-day period. Tadpoles 

(especially third-year tadpoles) clearly represent the greatest challenge for repatriating R. muscosa

in remote backcountry locations, but our use of mesh cages in 1995 showed that it could be 

accomplished with little or no mortality. 

Release of tadpoles, subadults, and adults in the Tableland area was completed with almost 

no mortality. It appears that the cages used at the release site might not have been necessary; 

however, moving amphibians between less similar sites might warrant this approach. It is difficult 

to judge whether the slow addition of water into the plastic bags used for transporting eggs and 

tadpoles was important, but we recommend it as a standard procedure that allows for a slow 

adjustment to differences in temperature and water chemistry. 

Our technique for repatriating R. muscosa eggs did not work well. Whether the eggs were 

eaten by predators, or survived and hatched, they all disappeared within a week. We recommend 

that repatriated eggs be placed in small fiberglass screen cages similar to those we used for holding 

tadpoles. This would keep the eggs in place until hatching, and allow for a more accurate 

assessment of short- and long-term survival of both eggs and early stage tadpoles. 

Survival of Repatriated Rana muscosa

Both frogs and tadpoles repatriated to the Tableland area appeared to grow and develop 

normally. Adult R. muscosa at the release sites showed substantial weight gains and small 

increases in length during the summer of 1995. In 1994, the PIT-tagged frogs were not recaptured 

and reweighed, as the field season was terminated by a heavy snow that fell only a few days after 

13 
the frogs were released at the Tableland area. Weight loss during the winter presumably occurred 

due to loss of fat reserves. By late summer of 1995, frogs reached a weight/length3 ratio similar to 

that measured late in the previous summer when they were first captured at the donor sites. This 

strongly suggests that frogs released in the Tableland area were able to obtain sufficient food, and 

grow at a normal rate. At three ponds in 1994, and at Far Pond in 1995, metamorphosis of tadpoles 

occurred since the maximum number of subadults substantially exceeded the number repatriated at 

the start of the season. Metamorphosis continued into 1996, particularly at Far Pond. These 

observations indicate that survival and successful development of third-year tadpoles occurred 

through metamorphosis. 

In spite of the growth of adults and development of tadpoles, long-term survival of R. 

muscosa was poor, and there was only limited reproduction. There was a clear downward trend in 

our counts in 1994-1998, despite variation between surveys. While the number of subadults 

increased initially in 1994 and 1995 as a result of metamorphosis, the number of subadult frogs 

declined by the end of each year. With the exception of Far Pond, there was almost no survival of 

subadults through the winter. Adult survival was also poor; adults disappeared precipitously at Full 

Moon Pond and Frog Lake, and more slowly at Far Pond. 

Tadpole counts for both second- and third-year individuals also declined rapidly, to nearly 

zero by the end of the summers of 1994 and 1995. These counts, however, were not indicative of 

the number present. Mid-season tadpole counts clearly underestimated the number present, as 

shown by the number of subadults appearing later in the season. The extremely low tadpole counts 

at the end of the season were also a poor reflection of actual numbers, at least in 1995, because 

third-year tadpoles became evident in mid-summer of 1996, a year when no new tadpoles were 

repatriated to the sites. 

Reproduction was extremely limited. Though we regularly found large numbers of egg 

masses at Sixty Lake Basin donor sites during surveys in 1994 and 1995, we never saw egg masses 

in the Tableland area. The only evidence of reproduction at the Tableland sites was in or near Far 

Pond, where we found a few first-year tadpoles in 1995, and a single second-year tadpole in 1998, 

three years after the last second-year tadpole had been released. These findings indicate that there 

was some reproduction in the Tableland area, but it was insufficient to maintain the population. 

The lack of significant survival or reproduction strongly suggests that the Tableland sites 

were not suitable for R. muscosa. Whatever caused the disappearance of R. muscosa from the 

Tableland during the late 1970s and 1980s still appears to have been inhibiting the survival of R. 

muscosa 10 - 15 years later. Other studies have shown that repatriations of R. muscosa can be 

successful if the factor causing the original decline has been eliminated. For example, in August 

2001, Roland Knapp (pers. comm.) repatriated 10 adult R. muscosa and 200 tadpoles into a lake in 

the Humphrey’s Basin in the Sierra Nevada where introduced trout had been removed. By late 

2002, the frog population consisted of approximately 100 adults and 300 first year tadpoles. This 

demonstrates that the relatively small number of adults used in the initial introduction was 

sufficient to allow reproduction and survival. Unfortunately, the population was extirpated because 

of a die-off apparently caused by the chytrid fungus Batrachochytrium dendrobatidis (Knapp, pers. 

comm.). However, as Dodd and Seigel (1991) and Dodd (2005) point out, most attempts at 

repatriation do not result in sustainable populations. 

Possible Causes for the Loss of Rana muscosa

Any explanation of the failure to reestablish R. muscosa in the Tableland area must account 

for both the conspicuous loss of adults and subadults, and the minimal amount of reproduction. 

Specifically, 1) All adults at Full Moon Pond disappeared during the winter of 1994-1995, and only 

14 
two survived the winter of 1995-1996; 2) All adults at Frog Lake disappeared during the winter of 

1995-1996 (they were not present in 1994); 3) Although adults at Far Pond survived both winters, 

few repatriated individuals survived until 1997, and relatively few of the frogs that metamorphosed 

at this site were found as adults in 1997; 4) Several adults at Far Pond in August 1997 were dead or 

dying, and many appeared sick; 5) Although many subadults at Far Pond survived the winter of 

1994-1995, survivorship was poor at this site through the winter of 1995-1996. Data on dispersal, 

weather, water quality, predation, disappearance of individuals by life stage, and contaminants were 

used to evaluate potential causes of decline. Fortunately, our study site was in a fishless area, so 

the impact of non-native trout was not a factor as it is throughout most of the Sierra Nevada 

(Vredenburg, 2004). 

Weather Patterns 

The most conspicuous deviation from normal weather patterns during our study (1994-

1997) was the winter of 1994-1995 (Fig. 22 - 23). October 1994 was colder than normal, and was 

followed by the coldest November in the more than 60 years that weather records have been kept 

(National Weather Service data, Grant Grove, CA). Beginning in January 1995, snowfall was 

much heavier than normal, delaying the summer thaw until the beginning of August 1995. Also, 

the preceding winter was drier and warmer than normal, so water levels were relatively low. These 

conditions were similar to the winter of 1977-1978, when adult R. muscosa did not survive the 

winter at many Tableland sites, including the three repatriation ponds in our study (Bradford, 

1983). Those die-offs were attributed to winterkill due to oxygen depletion in the water, which is 

more pronounced in shallow lakes and ponds. Thus, the disappearance of both adults and subadults 

from Full Moon Pond and Frog Lake during the winter of 1994-1995 may have occurred for this 

reason. For Full Moon Pond, while there was no temperature data logger in the pond during the 

1994-95 winter, the data logger at Far Pond showed that the pond was frozen to a depth of at least 

one meter, suggesting that the Full Moon Pond was probably frozen to or near to the bottom as 

well. Nevertheless, unusual temperatures and precipitation were not evident during the 1995-1996 

winter, and thawing at the release sites occurred in late June to early July (Fig. 15 - 17). 

Consequently, winterkill due to oxygen depletion or freezing was not likely to be responsible for 

the loss of adults and subadults at these two sites during the 1995-1996 winter. Temperature 

profiles at both of these sites indicated that the water did not freeze to the bottom (Fig. 16 - 17). 

Moreover, this does not account for the much greater survivorship of these life stages at Far Pond 

(our highest elevation site) than the other two sites during the winters of both 1994-1995 and 1995-

1996. Far Pond (2.7 m deep at high water) is shallower than Frog Lake (4.1 m at high water) and 

bottom temperature profiles during winter were more similar to Full Moon Pond than to Frog Lake 

(Fig. 15 - 17). 

Water Quality 

We measured pH and electrical conductivity (EC) to evaluate whether water quality played 

a role in the disappearance of R. muscosa. Lakes in the Sierra Nevada are typically low in acidneutralizing capacity and are, therefore, susceptible to acidification (Melack et al., 1985; Landers et 

al., 1987). Sierran Lakes are also low in ionic strength (Landers et al., 1987) and low pH levels 

would be expected to cause the most physiological stress at low ionic strengths (Freda and Dunson, 

1984). While the EC values we measured were low compared with other Sierran lakes (Eilers et 

al., 1987; Bradford et al., 1994b; Sickman, pers. comm.), it is unlikely that the EC and pH we 

observed would be deleterious to R. muscosa. In a study of amphibian habitats at high elevations 

throughout the Sierra Nevada, Bradford et al. (1994b) found no association between the 

15 
presence/absence of R. muscosa at a site and the pH or EC of the water. Moreover, the pH and EC 

values observed by Bradford et al. at sites inhabited by R. muscosa (e.g., minimum pH = 5.6, 

minimum EC = 3 μS/cm) included or were close to the values observed in our study (minimum pH 

= 5.6, minimum EC = 2 μS/cm). 

Predators 

Predators may have been a minor contributing factor in the loss of R. muscosa. In 1994, 

western terrestrial garter snakes were common at Table Meadow, Frog Lake, and Full Moon Pond. 

Five of 32 garter snakes contained the remains of R. muscosa. This included 3 of 6 snakes captured 

at Frog Lake, 2 of 18 at Full Moon Pond, and 0 of 8 at Table Meadow. We never observed snakes 

at Far Pond, where R. muscosa survived much longer than at the other three sites. The lack of 

snakes at Far Pond might be because that pond was in a granite basin with little vegetation. 

However, the three sites that did support snakes had historically supported large populations of R. 

muscosa. Garter snakes occur throughout the range of R. muscosa, but they occur almost 

exclusively at sites where either R. muscosa or P. regilla are present (Jennings et al., 1992; 

Matthews et al., 2002). Thus, the presence of this native snake is unlikely to be the primary cause 

of the loss of R. muscosa, especially since snakes would be inactive during winter when many adult 

and subadults disappeared. 

A single grebe was seen at two of the release sites, Full Moon Pond and Frog Lake. Even 

with careful, extended observations, we were unable to ascertain whether the grebe was eating R. 

muscosa. Regardless, it is unlikely that foraging by just one individual of this naturally occurring 

native predator would be the primary factor leading to the loss of frogs, particularly during the 

winter. 

Dispersal 

Of the 143 adult R. muscosa released at the Tableland sites, at least 22 (15.4%) dispersed to 

nearby ponds or streams. It would be useful to know whether the dispersing frogs were merely 

moving away from their release sites, or if they were heading in the direction of the donor ponds. 

Sixty Lake Basin donor sites were 30 km northeast of the Tableland. Twenty of the 22 dispersants 

moved north, and most went somewhat east of north. However, most of the dispersing frogs that 

we located were from Far Pond, and the only suitable frog habitat was downstream to the northeast 

(Fig. 9). Dispersal in any other direction would have led frogs to a steep talus slope where survival 

would have been unlikely, and where we would not have detected their presence. 

Two of the four frogs that dispersed from Full Moon Pond almost certainly traveled 

overland, rather than following a drainage channel, and to the northeast. We found only one frog 

that metamorphosed at a Tableland site that left its pond. That frog left Dispersal Pond 3 (where it 

was tagged as an adult) and went south to Far Pond. Pope and Matthews (2001) reported that 17% 

of their 500 PIT-tagged R. muscosa in Kings Canyon National Park moved overland during 1997 

and 1998, so this type of behavior has been documented in other nearby populations. 

During an extensive survey of the Tableland area in 2000, only four frogs were found (at 

Dispersal Pond 3, approximately 200 m downstream from Far Pond; Knapp, pers. comm.). It 

seems unlikely that dispersal alone would account for the loss of frogs, particularly during winter. 

Matthews and Pope (1999) evaluated movement of 24 R. muscosa using radiotransmitters. They 

found that movement varied seasonally with the greatest movement occurring in September with a 

mean distance moved of 145 m during that month, and the least movement at the onset of winter 

dormancy during October (43 m). These distances are similar to what we observed in the 

16 
Tableland area, hence it does not seem that dispersal from the release sites is a likely cause of the 

loss of frogs, especially considering that frogs were getting sick and dying at the release sites. 

Disease 

 Infection by the chytrid fungus B. dendrobatidis is a plausible cause for the loss of R. 

muscosa in the Tableland, both during the 1970s and 1980s, and during our experimental 

reintroduction in the 1990s. Prior to 1998, it was thought that chytrid fungi did not infect 

vertebrate hosts. In 1998, Berger et al. (1998) described chytrid infections in frogs. Several 

subsequent studies provided strong correlative evidence that B. dendrobatidis was involved with 

declines in frog populations in both Panama (Lips, 1999) and Australia (Berger et al., 1998). 

Fellers et al. (2001) reported B. dendrobatidis in R. muscosa from the Sierra Nevada, less than 150 

km north of the Tableland area. Recently, Rachowicz et al. (2006) demonstrated through extensive 

field surveys and laboratory and field experiments that chytridiomycosis was the proximate cause 

of numerous observed R. muscosa population declines in the southern Sierra Nevada. A 

conspicuous finding was that post-metamorphic stages of R. muscosa experience high mortality 

from chytrid infection, whereas tadpoles do not. Tadpoles infected with B. dendrobatidis survive 

to metamorphosis, but typically succumb to chytrid infection shortly after metamorphosis. This 

pattern is consistent with the die-offs and disappearances of adults, subadults, and recently 

metamorphosed frogs that were observed in the Tableland in the 1970s (Bradford, 1983; 1991), as 

well as during the present study. Since chytrid infection of frogs was not described until after our 

study, we did not look for it during our experimental repatriation. 

Bradford (1991) reported a massive die-off of R. muscosa in a Tableland population during 

the summer of 1979 that appeared to be caused by red-leg disease, an infection caused by the 

bacteria Aeromonas hydrophila. Carey et al. (1999) suggested that the 1979 die-off may have been 

caused by B. dendrobatidis and that the bacterial infections were secondary, a hypothesis that 

cannot be tested today. Aeromonas is unlikely to be involved with the loss of repatriated R. 

muscosa during our study since we found no evidence of this disease (reddening of the thighs) in 

any of the frogs we handled. 

Viral infections have been reported in Rana aurora (Mao et al. 1999). Die-offs caused by 

ranavirus typically kill only tadpoles and recently metamorphed (30-60 days) individuals, and there 

are often hundreds of dead tadpoles present at a site. By contrast, chytridiomycosis affects only 

adult anurans, often with only one or a few dead individuals present at a site (D.E. Green, pers. 

comm.). The extent of viral infections in California amphibians is unknown, but a large die-off of 

R. muscosa tadpoles in Kings Canyon National Park in 2001 appears to have been caused by an 

iridovirus (Knapp, pers. comm.). The significance of viral infections in declining amphibian 

populations remains largely unknown, but it does not appear to have been a factor in our study 

since we never observed tadpole die-offs. 

Pesticides 

Exposure to airborne pesticides is a possible cause for the Tableland population declines. 

Davidson and Knapp (2007) evaluated over 6800 sites in the southern Sierra Nevada for the 

presence of R. muscosa, the presence of introduced game fishes, habitat conditions, and the 

predicted exposure to windborne pesticides applied in upwind agricultural areas. In multivariate 

analyses, predicted exposure to pesticides had a pronounced negative effect on R. muscosa site 

occupancy, independent of other factors. This pattern is corroborated by our comparison of frogs 

from sites in the Tableland (an area near the Central Valley that has high predicted pesticide 

exposure) and frogs from Sixty Lake Basin (an area more remote from the Central Valley that has 

17 
low predicted pesticide exposure). When the survival of R. muscosa in the Tableland area seemed 

unlikely in 1997 and most of the remaining frogs appeared sick, the last 20 R. muscosa were 

collected so pesticide concentrations could be compared with a similar set of frogs collected at the 

Sixty Lake Basin donor sites. Several pesticides, especially pp-DDE, were found at higher 

concentrations in frog tissue from the Tableland sites (Fellers et al., 2004). 

Based on traditional toxicological studies that expose animals to contaminants for only brief 

periods of time (24 - 96 hr), it seems unlikely that the loss of R. muscosa was caused by the 

relatively low concentration of pesticides that have been found in the Tableland area. However, 

Relyea and Mills (2001) showed that increasing contaminant exposure from four to 10 days caused 

a significant increase in mortality. Thus, some of the contaminants in the Tableland may be present 

in concentrations sufficiently high to account for the loss of frogs. This is especially true for R. 

muscosa since they typically require three years for tadpoles to metamorphose, and 3 - 4 years for 

frogs to reach sexual maturity (Vredenburg et al., 2005). This means that R. muscosa tadpoles are 

exposed to contaminants in the water for an usually long time, possibly allowing them to 

accumulate more contaminants and making them (or the subsequent adults) more vulnerable 

(Sparling et al., 2001). In addition, it has been suggested that pesticide exposure may affect 

amphibian populations by suppressing immune function, thus making amphibians more susceptible 

to disease (Davidson and Knapp, 2007). 

Other Factors 

Several additional factors seem unlikely to account for the failure to re-establish 

populations. Introduced fish have been shown to dramatically affect the distribution and abundance 

of R. muscosa populations (Bradford, 1989; Knapp and Matthews, 2000). However, the Tableland 

area is largely devoid of fish and none occurred within 1 km of the study sites. Fellers and Drost 

(1983) suggested that fire suppression contributed to the loss of R. cascadae in northern California, 

but the vegetation in the Tableland area is not sufficient to support fires. There is no evidence that 

poor nutrition was a contributing factor, given that adults grew at a normal rate and tadpoles 

successfully metamorphosed in several years. It is possible that larger numbers of repatriated 

individuals would have resulted in greater success, but the repatriation of similar numbers of 

individuals elsewhere resulted in successful re-establishment of a population (Knapp, unpub. data). 

CONCLUSIONS 

Our study demonstrated the practicality of repatriating R. muscosa. We tested a variety of 

techniques for holding and moving all life history stages, and found that most of our techniques 

were both practical and appropriate for moving frogs between field locations. 

Frog populations did not become established after four years, even though tadpoles 

metamorphosed and adults increased in both weight and length. The mechanism for this failure 

appeared to be primarily loss of adults and subadults, and very little reproduction. We examined a 

number of factors that might have caused the declines, e.g., weather, water quality, predation, and 

dispersal. In addition, we evaluated the general health of repatriated frogs in terms of 

weight/length3

. None of these factors appeared to be the primary cause of the decline. Introduced 

fish were not involved due to their absence from our study area. Both pesticides and 

chytridiomycosis have the potential to have caused the observed declines, either individually or in 

combination with other stressors. Further research is needed to clarify the role of each stressor. 

While we did not identify the specific cause for either the original or subsequent loss of R. 

muscosa in the Tableland area of the Sierra Nevada, the evidence is compatible with 

18 
chytridiomycosis and contaminants as a primary cause of the decline. Either one of these factors, 

or the two acting in concert, may have made the Tableland area unsuitable for R. muscosa. 

Hopefully, ongoing research on R. muscosa and other anurans in the Sierra Nevada will help 

elucidate this situation and allow for reestablishment of viable R. muscosa populations. 

ACKNOWLEDGMENTS 

Bruce Christman, Jennifer Ellingson, Craig Fellers, Scott Fellers, Kathleen Freel, and Mark 

Massar assisted with the field work. Annie Esperanza, David Graber, Janie McLaughlin, and 

Harold Werner provided logistical support that was greatly appreciated. Roberta Larson assisted 

with data processing. Joan Fellers and Patrick Kleeman provided useful comments on the 

manuscript. The research was funded by the National Park Service. Sequoia and Kings Canyon 

National Parks, and the California Department of Fish and Game provided collecting permits. The 

U.S. Environmental Protection Agency (EPA), through its Office of Research and Development, 

collaborated in this project. The document has undergone EPA review and has been approved for 

publication. 

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Table 1. Historic records of Rana muscosa at the four Tableland area release sites at Sequoia National Park, CA 

data). The absence or very low numbers of adult frogs in 1978 at Frog Lake, Far Pond, and Full Moon Pond represdecline from the previous year (Bradford 1983). 

Site Life History Stage 1977 1978 1979 1980 1989 Table Adults + Subadults 52 65 54 5 7 Meadow Tadpoles present hundreds hundreds 15 14 Frog Adults + Subadults 48 + 1 0 0 0 Lake Tadpoles present 130 0 0 0 Far Adults + Subadults not visited 0 not visited not visited 0 Pond Tadpoles not visited 260 not visited not visited 0 Full Moon Adults + Subadults 33 + 0 0 1? 0 Pond Tadpoles not recorded present 9 0 0 

23 
Table 2. Rana muscosa repatriated in 1994 from Sixty Lake Basin (Kings Canyon National Park) to 

the Tableland sites (Sequoia National Park, CA). 

June 14 - 16 Sept. 20

2nd year 3rd year 

Release Site Egg Masses Tadpoles Tadpoles Subadults Adults 

Table Meadow 2 80 84 25 0 

Frog Lake 2 80 84 24 0 

Far Pond 2 80 84 25 25 

Full Moon Pond 2 78 84 23 25 

 

Totals 8 318 336 97 50 

24 
25 

Table 3. Rana muscosa repatriated in 1995 from Sixty Lake Basin (Kings Canyon National Park) to 

the Tableland sites (Sequoia National Park, CA). 

 August 26, 1995 

2nd year 3rd year 

Release Site Tadpoles Tadpoles Adults 

Table Meadow 0 0 0 

Frog Lake 96 108 31 

Far Pond 94 108 31 

Full Moon Pond 96 108 31 

 

Totals 286 324 93 
Table 4. Counts of Rana muscosa at Far Pond and adjacent dispersal ponds in 1996-1998. 

2nd Year 3rd Year 

Tadpoles Tadpoles Subadults Adults 

 Recruits1 

Previously Not Previously 

Repatriated2 Tagged Tagged 

7/10/96 0 0 2 2 0 3 7/12/96 0 0 5 9 0 2 + 1 dead 8/22/96 1 28 

12 + 4* + 2 

dead 6 0 9 + 14* 

10/1/96 0 0 6 7 2 5 10/3/96 0 0 10 10 7 4 7/15/97 0 0 0 2 4 (1 died) 5*+1 dead 7/16/97 0 1 1 1 0 3* (2 died) 7/17/97 0 2 0 1 3 2*(1 died) 7/20/97 0 4 1 1 6 4 8/19/97 0 0 5 4 6 5 + 1 dead 9/19/98 1** 0 0 0 0 1 

1. Recruits were adults without PIT tags when first captured at Far Pond in 1996-1998. Hence they developed into adults at Far Pond fthat had been repatriated in 1994 or 1995. 2. Repatriated frogs were captured at Sixty Lake Basin, PIT-tagged, and released at Far Pond in 1994 or 1995. 3. Not Captured frogs were adults seen but not caught, and hence not examined for PIT tags. * Number of adults or subadults without PIT tags that were tagged on this day. ** Located at pond Dispersal Pond 3, downstream from Far Pond (Fig. 9). 

26 
Table 5. Counts of Rana muscosa at the Full Moon Pond release site in the Tableland area (Sequoia 

National Park) in 1996-1998. Definitions as in Table 4. 

2

nd year Tadpoles 3rd Date year Tadpoles Subadults Adults

Repatriated Recruits

7/10/1996 0 4 0 1 0 

7/11/1996 0 0 0 1 0 

8/23/1996 0 33 2 0 0 

10/2/1996 0 0 0 0 0 

7/21/1997 0 0 0 0 0 

9/19/1998 0 0 0 0 0 

27 
Table 6. Counts of Rana muscosa at the Frog Lake release site in the Tableland area (Sequoia 

National Park) in 1996-1998. Definitions as in Table 4. 

2

nd year Tadpoles 3rd Date year Tadpoles Subadults Adults

Repatriated Recruits

7/10/1996 0 5 0 0 0 

7/11/1996 0 12 0 0 0 

8/23/1996 0 1 4 0 0 

10/2/1996 0 0 0 0 0 

10/3/1996 0 0 0 0 0 

7/19/1997 0 1 1 0 0 

8/20/1997 0 0 0 0 0 

9/19/1998 0 0 0 0 0 

28 
Table 7. Survival of PIT-tagged adult Rana muscosa released in 1994 at Far Pond and Full Moon 

Pond. Dates of the first and last surveys in 1995 were August 23 and October 19; dates for 1996 and 

1997 are provided in Tables 4 and 5. 

Far Pond Full Moon Pond

Number Released 25 25 

1994 Surveys* 18 19 

1995 Surveys** 

 First 15 0 

 Last 10 0 

1996 Surveys** 

 First 7 0 

 Last 5 0 

1997 Surveys** 

 First 3 0 

 Last 2 0 

*Maximum number of individuals observed during any single survey. 

** Maximum number of individuals known to be alive at the time of survey. The number of frogs captured during 

each survey was increased by the number of PIT-tagged individuals subsequently captured and hence known to be 

alive at the time of the survey. 

29 
Table 8. Survival of PIT-tagged adult Rana muscosa released in 1995 at three sites in the Tableland 

area. Dates of the first and last surveys in 1995 were August 27 and October 17 - 20, dates for 1996 

and 1997 are provided in Tables 4 and 5. 

 Far 

Pond

Full Moon 

Pond

Frog 

Lake

Number Released 31 31 31 

1995 Surveys

 First 31 20 22 

 Last 21 5 11 

1996 Surveys*

 First 15 2 0 

 Last 8 0 0 

1997 Surveys*

 First 2 0 0 

 Last 2 0 0 

* Maximum number of individuals known to be alive at the time of survey. The number of frogs captured during each 

survey was increased by the number of PIT-tagged individuals subsequently captured and hence known to be alive at 

the time of the survey. 

30 
31 

Table 9. Weight and snout-vent length of Rana muscosa when first captured at Sixty Lake Basin 

(Kings Canyon National Park) donor site. The ratio represents weight/length3

. 

Number Average Average Ratio 

Year Repatriated Weight (g) Length (cm) g/cm3

1994 50 18.5 5.66 0.102 

1995 93 14.7 5.54 0.086 
Table 10. Adult Rana muscosa weight and snout-vent length (SVL) gains at each of the three Tableland release s

were originally captured, tagged, weighed, and measured at Sixty Lake Basin on August 25, 1995, repatriated to th

next day, and recaptured on September 20, 1995. Numbers are means ± one standard deviation. 

 August 25, 1995 September 20, 1995 

Release Site N Weight (g) SVL (cm) Weight (g) SVL (cm) Weight (g

Far Pond 24 13.84 ± 3.32 5.45 ± 0.46 16.70 ± 3.29 5.62 ± 0.48 2.86 ± 1.45 Full Moon Pond 10 13.78 ± 4.04 5.37 ± 0.51 17.38 ± 4.32 5.52 ± 0.48 3.60 ± 0.51 Frog Lake 13 14.19 ± 3.94 5.51 ± 0.61 17.34 ± 4.48 5.69 ± 0.56 3.15 ± 1.42 

32 
Table 11. Number of western terrestrial garter snakes (Thamnophis elegans) observed, captured, and containing 

Tableland sites in 1994 and 1995. Rana muscosa and Pseudacris regilla are both frogs (mountain yellow-legged fr

Number Number Snake stomachs wi

Site Observed Captured Rana muscosa PseudacriTable Meadow 11 8 0 1 Frog Lake 6 6 3 0 Full Moon Pond 22 18 2 2 Far Pond 0 0 0 0 Totals 39* 32** 5 3 

* Only four observations were 1995. ** At least 16 of the 32 captured were different individuals based on marked scutes. 

33 
34 

Table 12. Concentration of pesticides (ng/g wet wt) in Rana muscosa tissue collected at the Tableland (Sequoia Nand the Sixty Lakes Basin (Kings Canyon National Park, n = 20) California, USA, 18 - 22 August 1997 (from Fellers e

α-HCHa γ-HCHa γ-chlordane trans-nonachlor α-endosu

TablelandMedian 1.16 0.07 0.71 1.72 0.5 Mean 1.41 103.1 0.84 2.66 0.56 Standard Deviation 1.24 221 0.75 2.6 0.36 Sixty LakesMedian 1.12 0.15 0.14 0.46 0.41 Mean 3.95 0.37 0.17 0.53 0.45 Standard Deviation 4.56 0.48 0.24 0.59 0.24 p-valuec 0.29 0.71 0 0 0.31 

a. HCH = hexachlorocyclohexane b. DDE = dichlorodiphenyldichloroethylene c. Mann-Whitney p-value using Chi-squared approximation 
Table 13. Concentration of pesticides (ng/liter) in surface water samples collected at the Tableland 

(Sequoia National Park) and the Sixty Lakes Basin (Kings Canyon National Park), California, 18 - 22 

August 1997 (from Fellers et al. 2004). Log Kow is an indicator of the degree to which a substance 

will bioaccumulate. Far Pond is referred to as G-049 in the table below. 

Tableland Sixty Lakes

Compound Log Kow Limit of Detectiona G-049 G-054 S-545 S-471 

γ-chlordane 5.2b 0.03 0.27 

α-chlordane 5.2b 0.03 

Chlorpyrifos 4.3b 0.03 12 0.72 0.22 0.17 

pp-DDE 6.9c 0.1 0.31 

o,p'-DDT 6.8b 0.1 0.46 

p,p'-DDT 6.9c 0.1 

Diazinon 3.4b 0.06 3.1 3.4 1.8 

α-endosulfan 3.6d 0.03 0.78 1 0.3 0.37 

β-endosulfan 3.6d 0.05 0.4 0.42 1.8 0.17 

endosulfan sulfate 0.03 2.9 2.2 0.33 0.4 

α-HCH 3.81d 0.03 0.29 

γ-HCH 3.8d 0.03 

trans-nonachlor 0.04 0.31 

Trifluralin 4.6b 0.1 2.5 

a. Analytical detection limit was three times the standard deviation of blank levels (LeNoir et al., 1999). 

b. Selected values from Finizio et al., 1997. 

c. de Bruijn et al., 1989. 

d. Selected values from Suntio et al. 1988. 

35 
Figure 1. Location of the four Rana muscosa release sites in the Tableland area of Sequoia National 

Park, California. Map based on USGS 1:24000 Lodgepole, California topographic map. Contour lines 

are 60 feet. 

36 
Figure 2. Counts of Rana muscosa at Far Pond and the adjacent dispersal ponds, Sequoia National Park, in 1994. 

year tadpoles, third-year tadpoles, and subadult frogs were released at Far Pond on June 14, 1994. Adult R. muscthere on September 20, 1994. See Table 2 for numbers of each life history stage repatriated. 

0

102030405060708090

100

6/14/1994 6/21/1994 6/28/1994 7/5/1994 7/12/1994 7/19/1994 7/26/1994 8/2/1994 8/9/1994 8/16/1994 8/23/1994 8/30/1994 9/6/1994 9/13/1994 9/20/1

Number

Adults Subadults Third Year Tadpoles Second Year Tadpoles

37 
Figure 3. Counts of Rana muscosa at Full Moon Pond and the adjacent dispersal ponds, Sequoia National Park, in 

second-year tadpoles, third-year tadpoles, and subadult frogs were released at Far Pond on June 14, 1994. Adult released there on September 20, 1994. See Table 2 for numbers of each life history stage repatriated. 

0

102030405060708090

100

6/14/1994 6/21/1994 6/28/1994 7/5/1994 7/12/1994 7/19/1994 7/26/1994 8/2/1994 8/9/1994 8/16/1994 8/23/1994 8/30/1994 9/6/1994 9/13/1994 

Number

 Adults Subadults Third Year Tadpoles Second Year Ta

38 
Figure 4. Counts of Rana muscosa at Frog Lake and the adjacent dispersal ponds, Sequoia National Park, in 1994. 

second-year tadpoles, third-year tadpoles, and subadult frogs were released at Far Pond on June 14, 1994. Adult 

released there on September 20, 1994. See Table 2 for numbers of each life history stage repatriated. 

0

102030405060708090

100

6/14/1994 6/21/1994 6/28/1994 7/5/1994 7/12/1994 7/19/1994 7/26/1994 8/2/1994 8/9/1994 8/16/1994 8/23/1994 8/30/1994 9/6/1994 9/13/1994 

Number

Subadults Third Year Tadpole Second Year Tadpole

`

39 
Figure 5. Counts of Rana muscosa at Table Meadow and the adjacent dispersal ponds, Sequoia National Park, in 

second-year tadpoles, third-year tadpoles, and subadult frogs were released at Far Pond on June 14, 1994. No ad

released there. See Tables 2 and 3 for the numbers and dates of repatriation for each life history stage in 1994 an

0

102030405060708090

100

6/14/1994 6/21/1994 6/28/1994 7/5/1994 7/12/1994 7/19/1994 7/26/1994 8/2/1994 8/9/1994 8/16/1994 8/23/1994 8/30/1994 9/6/1994 9

Number

Subadults Third Year Tadpoles Second Year Tadpoles

`

40 
Figure 6. Counts of Rana muscosa at Far Pond and the adjacent dispersal ponds, Sequoia National Park, in 1995. 

tadpoles, third-year tadpoles, and adult frogs were released at Far Pond on August 26, 1995. See Tables 2 and 3 fdates of repatriation for each life history stage in 1994 and 1995. 

0

20406080

100120

8/23/1995 8/30/1995 9/6/1995 9/13/1995 9/20/1995 9/27/1995 10/4/1995 10/11/1995 10/

Number

 Adults Subadults Third Year Tadpoles Second Year Tadpoles

41 
Figure 7. Counts of Rana muscosa at Full Moon Pond and the adjacent dispersal ponds, Sequoia National Park, in 

tadpoles, third-year tadpoles, and adult frogs were released at Far Pond on August 26, 1995. See Tables 2 and 3 fdates of repatriation for each life history stage in 1994 and 1995. 

0

20406080

100120

8/23/1995 8/30/1995 9/6/1995 9/13/1995 9/20/1995 9/27/1995 10/4/1995 10/11/1995 10/1

Number

 Adults Subadults Third Year Tadpoles Second Year Tadpoles

42 
Figure 8. Counts of Rana muscosa at Frog Lake and the adjacent dispersal ponds, Sequoia National Park, in 1995. 

tadpoles, third-year tadpoles, and adult frogs were released at Far Pond on August 26, 1995. See Table 3 for numhistory stage repatriated to this site. 

0

20406080

100120

8/23/95 8/30/95 9/6/95 9/13/95 9/20/95 9/27/95 10/4/95 10/11/95 

Number

 Adults Subadults Third Year Tadpoles Second Year Tadpoles

43 
Figure 9. Dispersal of Rana muscosa from Far Pond, Sequoia National Park. Adjacent ponds 

(numbered) are referred to as Dispersal Ponds (DP). Arrows in the figures indicate the sites at 

which the frogs were last detected. Twelve frogs dispersed to Dispersal Pond 3, one frog to 

Dispersal Pond 5, and one frog to Dispersal Pond 6. See Fig. 1 for location map. 

44 
Figure 10. Dispersal of Rana muscosa from Full Moon Pond, Sequoia National Park. Arrows in the 

figures indicate the sites at which the frogs were last detected. Each arrow represents the 

dispersal of one frog. See Fig. 1 for location map. 

 

45 
Figure 11. Dispersal of Rana muscosa from Frog Lake, Sequoia National Park. Arrows in the figures 

indicate the sites at which the frogs were last detected. Each arrow represents one frog. See Fig. 1 

for location map. 

46 
Figure 12. Frog 1760 weight (g) before and after repatriation from Sixty Lake Basin, Kings Canyon 

National Park, to Far Pond, Sequoia National Park. Frog was a male; SVL 4.8 cm when captured at 

Sixty Lake Basin on September 15, 1994. It was released at Far Pond on September 20, 1994. It had 

a SVL of 5.7 cm at last capture at Far Pond on August 18, 1997. 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

8/1/1994

11/1/1994

2/1/1995

5/1/1995

8/1/1995

11/1/1995

2/1/1996

5/1/1996

8/1/1996

11/1/1996

2/1/1997

5/1/1997

8/1/1997

Weight (grams)

47 
Figure 13. Frog 3173 weights (g) before and after repatriation from Sixty Lake Basin to Far Pond. 

Frog was a male; SVL 5.0 cm when captured at Sixty Lake Basin on August 25, 1995. It was released 

at Far Pond on August 26, 1995. It had a SVL of 5.7 cm at last capture at Far Pond on August 18, 

1997. 

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

8/1/1995

11/1/1995

2/1/1996

5/1/1996

8/1/1996

11/1/1996

2/1/1997

5/1/1997

8/1/1997

Weight (grams)

48 
Figure 14. Water Temperatures at Far Pond, Sequoia National Park, 1994-1995. The temperature 

loggers were deployed at depths of 0.5 and 1.0 meters above the bottom, at a time when the water 

level was approximately 1.0 meter deep. The data loggers were retrieved on August 23, 1995 when 

the water level was approximately one meter deeper. 

-1

4

9

14

19

24

8/5/94

9/5/94

10/5/94

11/5/94

12/5/94

1/5/95

2/5/95

3/5/95

4/5/95

5/5/95

6/5/95

7/5/95

8/5/95

Temperature (oC)

 Shallow Deep 

49 
Figure 15. Far Pond, Sequoia National Park, temperature at the surface and on the bottom at the 

deepest point, September 26, 1995 to August 21, 1996. Darker line is temperature recorded at the 

surface. 

20

0

15

10

5

20 9/26/95

10/26/9511/25/9512/25/95

1/24/962/23/963/24/964/23/965/23/966/22/967/22/968/21/96

Temperatue (

oC)

-5

50 
Figure 16. Full Moon Pond, Sequoia National Park, temperature at the surface and on the bottom at 

the deepest point, September 26, 1995 to August 21, 1996. Darker line is temperature recorded at 

the surface. 

20

0

15

10

5

9/26/95

10/26/9511/25/9512/25/95

1/24/962/23/963/24/964/23/965/23/966/22/967/22/968/21/96

Temperatue (

oC)

-5

51 
Figure 17. Frog Lake, Sequoia National Park, temperature at the surface and on the bottom at the 

deepest point, September 26, 1995 to August 21, 1996. Darker line is temperature recorded at the 

surface. 

20

0

15

10

5

9/26/95

10/26/9511/25/9512/25/95

1/24/962/23/963/24/964/23/965/23/966/22/967/22/968/21/96

Temperatue (

oC)

-5

52 
Figure 18. pH values during 1994 at the four Tableland release sites, Sequoia National Park. 

5.0

5.5

6.0

6.5

7.0

7.5

8.0

6/15/94 6/29/94 7/13/94 7/27/94 8/10/94 8/24/94 9/7/94 9/21/94 10/5/94

pH

 Far Pond Full Moon Pond Frog Lake Table Meadow 

53 
Figure 19. pH values during 1995 at the four Tableland release sites, Sequoia National Park. 

5.0

5.5

6.0

6.5

7.0

7.5

8.0

6/15/95 6/29/95 7/13/95 7/27/95 8/10/95 8/24/95 9/7/95 9/21/95 10/5/95

pH

 Far Pond Full Moon Pond Frog Lake Table Meadow

54 
Figure 20. Electrical conductivity values during 1994 at the four Tableland release sites, Sequoia 

National Park. 

0

5

10

15

20

25

30

35

6/15/94 6/29/94 7/13/94 7/27/94 8/10/94 8/24/94 9/7/94 9/21/94 10/5/94

Electrical Conductivity (μS/cm) 

 Far Pond Full Moon Pond Frog Lake Table Meadow

55 
Figure 21. Electrical conductivity values during 1995 at the four Tableland release sites, Sequoia 

National Park. 

0

1

2

3

4

5

6

7

8

9

10

6/15/95 6/29/95 7/13/95 7/27/95 8/10/95 8/24/95 9/7/95 9/21/95 10/5/95

Electrical Conductivity (μS/cm) 

 Far Pond Full Moon Pond Frog Lake Table Meadow

56 
Figure 22. Departures from long-term average daily temperature and precipitation for 1993 - 1994 

(measured at Grant Grove, CA, 32 km NW of the Tablelands). Temperature is o C and precipitation is 

cm. 

-15

-10

-5

0

5

10

Jul Aug Sep Oct Nov Feb Apr May Jun

Departure from Average .

Temperature Precipitation

57 
Figure 23. Departures from long-term average daily temperature and precipitation for 1994 - 1995 

(measured at Grant Grove, CA, 32 km NW of the Tablelands). Temperature is o

 C and precipitation is 

cm. 

-10

0

10

20

30

40

Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun

Departure from Average .

Temperature Precipitation

58