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Published accounts describe the eggs of spotted frogs (Rana luteiventris and Rana pretiosa) as having either 1 or 2 jelly envelopes surrounding the ovum. Eggs of R. luteiventris are typically reported to have a single jelly envelope, whereas those of R. pretiosa are reported to have 2 envelopes. We found, however, that both species' eggs actually have 3 jelly envelopes. In this paper we describe the eggs of both species, and identify the origin of the discrepancy in the scientific literature.

The Oregon Spotted Frog (Rana pretiosa) is endemic to the Pacific Northwest and was recently listed as threatened under the Endangered Species Act. We tested the hypothesis that reproductive or physiological stress and parasitic disease may be contributing to the decline of this species. We histologically examined gonads and kidneys of newly metamorphosed wild-caught R. pretiosa to confirm sex and search for evidence of abnormal reproductive development and parasites. A subset of these specimens were also cleared and stained for examination of their skeletal morphology to identify potential skeletal malformations. The sex ratio did not differ significantly from 1:1, and we found no skeletal abnormalities. Trematode metacercarial parasites were present in the kidneys of all Spotted Frogs examined. We also report, for the first time, oocytes developing in the testes of 5 out of the 11 newly metamorphosed male Spotted Frogs examined. Further study into gonadal development of this species is necessary to investigate the significance of testicular oocytes in developing R. pretiosa and to identify whether these gonadal abnormalities are related in any way to their decline.

Placobdella sophieae Oceguera-Figueroa et al., 2010 (Hirudinida: Glossiphoniidae) is reported from Oregon, California, and British Columbia for the first time. New hosts reported for P. sophieae include Taricha granulosa (rough- skinned newt), Rana pretiosa (Oregon spotted frog), and Anaxyrus boreas (western toad). Placobdella sophieae exhibits relatively low host specificity and all amphibians occurring in the Pacific Northwest are potential hosts.

minima, egg mass, oviposition More than half of the known remaining populations of the Oregon Spotted Frog (Rana pretiosa) are at elevations .1200 m along the Cascade Range and its eastern flank in Oregon (Pearl and Hayes 2005). Rana pretiosa in this region typically breed soon after thaw and often lay eggs in water ,20 cm deep (Pearl and others 2009). Egg masses in shallow microhabitats experience broad temperature fluctuations, and ice formation on the surface is common (Bull and Shepherd 2003). At .20 oviposition sites around Sunriver in central Oregon (elevation 1270 m), we have observed high survival of R. pretiosa embryos after exposure to subfreezing air temperatures and ice cover for up to several days. These observations and the characteristics of oviposition sites across much of the species’ range along the Cascade Range suggest that R. pretiosa eggs in this region may be more tolerant of low temperatures than previously reported. Information on thermal limits of R. pretiosa embryos derives from studies of 1 population in the Fraser River Valley of southwestern British Columbia. The low elevation of this site (approximately 50 m above sea level) and its proximity to the Strait of Georgia and Pacific Ocean make its climate more moderate than much of the extant range of R. pretiosa. Licht (1971) reported a lethal minimum, the temperature at which egg survival is ,50%, near 66C for eggs from that site at a range of stable temperature treatments in the laboratory. A subset of embryos survived lower temperatures for up to 8 h, after which trials were terminated (Licht 1971), but data were not presented on presence or timing of develop

We used genetic methods to estimate the effective number of breeders (N b) in a population of Rana pretiosa, an imperiled amphibian in western North America. Microsatellite data was gathered from large samples of adults, eggs, and juveniles collected in 2006. We wished to determine where in the life cycle the greatest reductions in N b occur, and to compare genetic estimates of N b to an egg mass count estimate of the number of breeding adults. We predicted that N b estimated at the metamorph stage would be reduced by increased variance in family size due to egg mass mortality. Contrary to our prediction, estimates of N b at the egg and metamorph stages were similar. Thus, we found no evidence of inflated variance in family size between the two stages. If our results for this population are typical for R. pretiosa, then increased variance in family size during the egg to metamorph stage may not be a strong factor in reducing the effective population sizes (N e) relative to the census sizes (N) in this species.

We used five years of recapture data and Bayesian estimation to assess seasonal survival, movement, and growth of Oregon Spotted Frogs (Rana pretiosa) relocated into created ponds at Dilman Meadow in Oregon, USA. We evaluate hypotheses specific to the relocation and elucidate aspects of R. pretiosa life history that are poorly known. The odds of survival of relocated individuals during the first year following relocation were 0.36 times the survival odds of relocated and non-relocated frogs after one year since the relocation. Survival rate was higher for large frogs. After accounting for frog size, we found little variation in survival between ponds at Dilman Meadow. Survival was lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. The highest survival rates occurred during winter for both genders, and one small spring was used heavily during winter but was used rarely during the rest of the year. Individual growth was higher in ...

Chytridiomycosis (infection by the fungus Batrachochytrium dendrobatidis) has been associated with amphibian declines in at least four continents. We report results of disease screens from 210 pond-breeding amphibians from 37 field sites in Oregon and Washington. We detected B. dendrobatidis on 28% of sampled amphibians, and we found ≥ 1 detection of B. dendrobatidis from 43% of sites. Four of seven species tested positive for B. dendrobatidis, including the Northern Red-Legged Frog (Rana aurora), Columbia Spotted Frog (Rana luteiventris), and Oregon Spotted Frog (Rana pretiosa). We also detected B. dendrobatidis in nonnative American Bullfrogs (Rana catesbeiana) from six sites in western and central Oregon. Our study and other recently published findings suggest that B. dendrobatidis has few geographic and host taxa limitations among North American anurans. Further research on virulence, transmissibility, persistence, and interactions with other stressors is needed to assess the potential impact...

A new species of ectoparasitic glossiphoniid leech was found feeding on frogs in the Nature Center Pond and elsewhere in Deschutes County, Oregon. The new species of Placobdella resembles the southern alligator leech, Placobdella multilineata Moore, 1953, notwithstanding their vast geographic separation in North America. The new species is readily distinguished by possessing subdivided annuli, by its papillation and pigmentation patterns as well as by the arrangement of ovarian tissues. There is strong evidence of nocturnality and of the potential for parasitizing humans.

From 2001 to 2005, we studied the demography and seasonal movement of Oregon spotted frogs (Rana pretiosa) translocated into created ponds in Dilman Meadow in central Oregon. Our objectives were to inform future monitoring and management at the site, and to elucidate poorly known aspects of the species’ population ecology. Movement rates revealed complementary use of sites seasonally, with one small spring being preferred during winter that was rarely used during the rest of the year. Growth rates were significantly higher in ponds that were not used for breeding, and larger size resulted in significantly higher survival. When variation in survival by size was accounted for there was little variation among ponds in survival. Seasonal estimates of survival were lowest for males during the breeding/post-breeding redistribution period, suggesting a high cost of breeding for males. Overwintering survival for both genders was relatively high. Our study supports others in suggesting Oregon spotted frogs are specific in their overwintering habitat requirements, and that predator-free springs may be of particular value. We suggest that any future monitoring include measures of the rate of pond succession. Demographic monitoring should include metrics of both frog reproduction and survival: counts of egg masses at all ponds during spring, and capture-recapture study of survival in mid and late summer when capture rates are highest. Additional study of early life stages would be particularly useful to broaden our understanding of the species’ ecology. Specifically, adding intensive capture and marking effort after larval transformation in fall would enable a full understanding of the annual life cycle. Complete study of the annual life cycle is needed to isolate the life stages and mechanisms through which Oregon spotted frogs are affected by stressors such as nonnative predators. Dilman Meadow, which lacks many hypothesized stressors, is an important reference for isolating the life stages most responsive to management elsewhere in the species’ range. Oregon Spotted Frog (Rana pretiosa) Movement and Demography at Dilman Meadow: Implications for Future Monitoring By Nathan D. Chelgren, Christopher A. Pearl, Jay Bowerman, and Michael J. Adams