An Ecological Life Table for the Salamander Eurycea wilderae

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Abstract
Fall and winter samples of Eurycea wilderae from a small stream in the Blue Ridge Mountains of southwestern North Carolina [USA] provided data for an ecological life table. In this population, oviposition occurred in late winter and early spring, followed by hatching in late spring and early summer. The salamanders then spent 1 or 2 yr as larvae, followed by at least a year as juveniles. Age at first reproduction in both sexes was estimated to be either 3 or 4 yr, but ususally the latter, since most individuals metamorphosed at 2 yr. Two morphs of mature males were observed. Males having cirri were smaller than males lacking cirri, suggesting that the variation was ontogenetic. Age structure was determined from the representation of life-history stages in the samples, after adjustment for early metamorphosis. From the age class estimates, annual survivorship values for the first 3 yr of life were calculated from the ratios of frequencies of successive age classes. For later years I assumed constant postmetamorphic survivorship and estimated this value from the ratio 3 yr to 4 yr and older individuals. Fecundity was determined by dissecting gravid females and calculating a least-squares regression of egg number against snout-vent length. The survivorship and fecundity data allowed completion of the life table and calculation of R0, which was 0.821. Such a low value probably reflects sampling and interpretive errors; otherwise a value of R0 < 1.0 is indicative of a declining population. By making no assumptions concerning R0, but assuming a stable age distribution, mean generation time was calculated as 4.4 yr. Pronounced variation in this and other life-history traits among E. wilderae and other Appalachian plethodontids stands in contrast to relative invariance in age at first reproduction in these salamanders.