Society for the Study of Amphibians and Reptiles Patterns of Growth and Movements in a Population of Ensatina eschscholtzii platensis (Caudata: Plethodontidae) in the Sierra Nevada, California Author(s): Nancy L. Staub, Charles W. Brown and David B. Wake Source: Journal of Herpetology, Vol. 29, No. 4 (Dec., 1995), pp. 593-599 Published by: Society for the Study of Amphibians and Reptiles Stable URL: http://www.jstor.org/stable/1564743 Accessed: 03-02-2016 23:13 UTC REFERENCES Linked references are available on JSTOR for this article: http://www.jstor.org/stable/1564743?seq=1&cid=pdf-reference#references_tab_contents You may need to log in to JSTOR to access the linked references. 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Society for the Study of Amphibians and Reptiles is collaborating with JSTOR to digitize, preserve and extend access to Journal of Herpetology. http://www.jstor.org This content downloaded from 136.152.142.101 on Wed, 03 Feb 2016 23:13:43 UTC All use subject to JSTOR Terms and Conditions Journal of Herpetology, Vol. 29, No. 4, pp. 593-599, 1995 Copyright 1995 Society for the Study of Amphibians and Reptiles Patterns of Growth and Movements in a Population of Ensatina eschscholtzii platensis (Caudata:Plethodontidae) in the Sierra Nevada, California NANCY L. STAUB,1CHARLES W. BROWN,2AND DAVID B. WAKE3 'Departmentof Biology,Gonzaga University, Spokane, Washington 99258, USA, 2Departmentof Biology,Santa Rosa Junior College, Santa Rosa, California 95401, USA, and 3Departmentof IntegrativeBiology and Museum of VertebrateZoology, University of California, Berkeley,California 94720-3160, USA ABSTRACT.- Movements and growth in a population of the terrestrialplethodontid salamanderEnsatina eschscholtzii platensis were investigated using mark-recapturemethods over a period of 1946 days at a mid-elevation site in the central Sierra Nevada of California. The study site included two plots of equal size, totaling 3.0 ha, in an old-growth pine-fir-incense cedar forest. Our sample included 925 captures,and 14%of the animals were recaptured at least once. Males were more active than females; recapture rates were significantly higher for males than for females, despite a 1:1 sex ratio. Variance in distance traveled was significantly greater for males than for females, and most long-range movements were by males, but mean distance traveled did not differ significantly between sexes. The maximum distance moved for males and females was 120.4 m and 60.6 m, respectively. These movement differences between sexes may explain differences in patterns of mtDNA and allozyme variation within the Ensatinaspecies complex. We suggest that terrestrialplethodontids routinely travel distances > 10 m and caution against calculating home-range sizes from studies conducted only on plots of small size. Ensatinaeschscholtzii is a terrestrial plethodon- Park, Calaveras Co., California, at an average tid salamander that is widespread in mesic elevation of 1400 m (see Fig. 1 in Wake et al., western North America. It passes its entire life 1989). Two 1.5 ha study plots were established cycle on land; there is no breeding migration, on either side of Moran Creek, a small perma- and salamanders avoid standing or flowing wa- nent stream. Each plot extended along the creek ter. Systematics and biogeography of the En- for 100 m, and up the respective creek bank for satina complex have been under study (cf. Wake 150 m. Grid lines from the plot perimeter were and Yanev, 1986; Moritz et al., 1992; Jackman laid every 10 m and numbered stations were and Wake, 1994), and ecological data are needed established at sites of intersecting lines. At each for estimating extent of gene flow and other of these sites a pitfall trap was established with- population genetic parameters. in 1 m of the point of intersection (trees, logs, In September, 1985, we initiated a long-term and rocks were avoided). Pitfall traps were used study of movement patterns in Ensatina esch- to minimize the amount of disturbance to the scholtzii platensis. Prior ecological studies had habitat (e.g., log turning). Traps were far more been conducted only for populations of E. e. effective than day-time or night-time searches eschscholtziiin southern California and E. e. xan- for salamanders (unpubl data). The traps were thoptica in the East Bay Region of central coastal round cans 18 cm deep and 16 cm in diameter. California (Stebbins, 1954). These taxa differ Each trap was provided with drain holes and a substantially in allozymes and mitochondrial bed of wet wood shavings and covered with DNA from the population studied (Wake and either a log or piece of bark. There were 176 Yanev, 1986; Moritz et al., 1992). The primary traps per plot. On the south plot an additional goal of our study was to compare movement pitfall trap was installed within 1 m of the cen- patterns of males and females, and estimate ter of each 10 x 10 m section. Thus, the south home range size. In addition, growth rates and plot contained 150 more traps than the north longevity were determined. plot. The north plot was flatter and received more sun than the south plot; the south plot MATERIALSAND METHODS was more densely vegetated at ground level. The study site is in old growth forest of pon- Both plots had nearly full canopy cover from derosa pine (Pinus ponderosa), sugar pine (Pinus towering old growth trees. lambertiana), incense cedar (Calocedrus decur- The central Sierra Nevada experiences sharp rens), white fir (Abies concolor) and black oak seasonality in climate that affects salamander (Quercus kelloggii) in Calaveras Big Trees State movements. Feeding and courting are restricted This content downloaded from 136.152.142.101 on Wed, 03 Feb 2016 23:13:43 UTC All use subject to JSTOR Terms and Conditions 594 N. L. STAUB ET AL. to periods when the ground surface is moist Smirnov test compared the distributions for m (Stebbins, 1954). This site receives on average moved/day and cumulative m moved between 1500 mm precipitation per year, and rainfall males and females. The chi-square test was used occurs primarily from September or October to compare the number of captures and recap- through early May. Surface conditions become tures between the north and south plots and progressively drier from mid-April through the the frequency of movements >20 m between summer, and the habitat is too dry for surface males and females. We also tested the sex ratio activity for 4-5 mo. Snow falls on the site every of captures and recaptures using the chi-square year, usually between December and February, test. Statview 512+ was used for the above com- but the amount is highly variable. Snow cover parisons. We also tested for differences between persists for more than a month on only limited sexes in the variance of cumulative distance parts of the site. moved (log transformed) (Sokal and Rohlf, Traps were monitored every 1-4 wk during 1981). Individuals that matured during the study the wet season, from September, 1985, through were excluded from analyses unless otherwise March, 1988. Spacing of visits was dependent noted. on weather and was more frequent when con- RESULTS ditions were judged to be suitable for activity. A few specimens (<1% of the total) may have TrappingSuccess.--A total of 925 living sala- spent as long as 4 wk in a trap, but only during manders (including recaptures) were captured the coldest time of the year. Occasionally it was during the study (30 dead salamanders [nearly impossible to check all traps because of heavy all drowned] and 12 tails without bodies were snow. Tree falls necessitated the minor relo- also found in the traps). Successful traps typi- cation of a few traps. 1988 was a year of severe cally contained one animal, but from two to drought and surface salamander movements seven (a unique event) salamanders were found ceased by mid-March. The study was then sus- in a single trap. On 26-27 October 1985, 155 pended in anticipation of a controlled burn. animals were captured (389 empty traps, 90 with However, the burn was not conducted and one animal, 17 with two, four with three, one monitoring was reinitiated from early Novem- with four and one with seven). The second most ber, 1990, to January, 1991. successful trapping produced 77 animals (30 Individual E. e. platensishave a distinctive col- November 1990). On several trapping occasions or pattern, consisting of reddish orange dorsal no animals were found in any of the 502 traps. spots or blotches on a gray-brown background. We caught a lower proportion of juveniles than Salamanders retrieved from pitfall traps were observed by Stebbins (1954) for a population of photographed in color using a camera with a E. e. xanthoptica.In the laboratory we found that fixed focal length. Each salamander was sexed juveniles placed in traps are able to climb out, (juvenile, male, or female) and photographed while adults do so rarely. Thus, we suspect that against a centimeter grid with a label indicating juveniles escape traps more readily than do date, capture site, and the sequential number adults. of each captured salamander. Salamanders were One hundred eleven animals were recap- returned to cover objects within 1 m of their tured at least once (14% of total), including 25 site of capture.