Growth, Age at Maturity, and Age-Specific Survival of the Arboreal Salamander (Aneides lugubris) on Southeast Farallon Island, California DEREK E. LEE, 1,2 JAMES B. BETTASO, 4 MONICA L. BOND, 1,3 RUSSELL W. BRADLEY, 1 JAMES R. TIETZ, 1 AND PETER M. WARZYBOK 1 1 PRBO Conservation Science, 3820 Cypress Drive, Suite 11, Petaluma, California 94954 USA 4 U.S. Fish and Wildlife Service, 1655 Heindon Road, Arcata, California 95521 USA ABSTRACT.—Growth, age at maturity, and survival are life-history parameters that provide important information for understanding population dynamics. ; We modeled growth and age at maturity for an island population of Arboreal Salamanders, Aneides lugubris, using snout–vent length (SVL) growth intervals from a 4-yr capture–mark–recapture study fit to the von Bertalanffy growth interval model. We estimated annual survival as a function of SVL using a multistate open robust design model, and computed age-specific survival using results from the von Bertalanffy growth model. Arboreal Salamanders have indeterminate growth that slows with age from hatchling size (24.4-mm SVL) to the mean adult (asymptotic) size of 66.0-mm SVL. Age at maturity is 2.69 yr, and average adult age is 8–11 yr. Annual survival increased with age from 0.363 in age 0 to 0.783 in ages .4 yr. Our results provide the first estimates of life-history parameters for this species and indicate similarities to other terrestrial salamanders from low-elevation Mediterranean climates. Quantifying life-history and demographic parameters en- ables ecologists to interpret and understand population dynamics of animals (Lebreton et al., 1992; Caswell, 2001). For example, growth rates, age at first reproduction, and age- specific survival are important parameters in life-history models (Cole, 1954; MacArthur and Wilson, 1967). Growth and survival depend on population density, competition, and health factors as well as environmental conditions such as food availability or climate (Schoener and Schoener, 1978; Morrison and Hero, 2003). Therefore, life-history characteristics can be used to make comparisons among populations and to examine effects of management activities (Morrison and Hero, 2003; Bruce, 2005). A larger proportion of amphibian species are at risk of extinction than of any other taxon (Wake and Vredenburg, 2008), yet few demographic studies of marked individuals have been conducted on salamanders (but see Tilley, 1980; Marvin, 2001; Waldron and Pauley, 2007). Most plethodontids are relatively long lived, slow to mature, and have lower fecundity than most anurans (Petranka, 1998), < rendering them particularly sensitive to conditions that influence adult survival (Benton and Grant, 1996). The majority of recent work on demography of plethodontid salamanders has been focused on the southeastern United States (Waldron and Pauley, 2007). We present empirical data from the first 4 yr of a capture–mark–recapture (CMR) study to determine growth rates and demographic characteristics of an island- dwelling population of the plethodontid Arboreal Salamander (Aneides lugubris) from California, USA. The largest species of the genus Aneides, the Arboreal Salamander is a California near-endemic, occurring in coastal oak woodlands, conifer forests, and shrublands from Humboldt County to northern Baja California, Mexico, including the offshore islands of South Farallon, Los Coronados, Catalina, and An ˜ o Nuevo and several smaller islands in the San Francisco Bay (Stebbins, 1951; Anderson, 1960; Petranka, 1998). The Arboreal Salamander has no aquatic larval stage, eggs are laid in terrestrial nests, and hatchlings resemble miniature adults (Wake and Hanken, 1996). The Arboreal Salamander is the only herptile inhabiting the South Farallon Islands, a set of offshore rocky islands situated on the edge of the continental shelf in the Pacific Ocean. Localized management activities at Southeast Farallon Island, such as eradication of invasive plants and mice, could adversely impact salamanders, particularly if chemicals are used extensively, but such activities also could have positive effects by removing competitors. Baseline demographic data are critical to documenting effects of existing and future changes to salamander populations (Bailey et al., 2004). We initiated this long-term CMR study in 2006 to provide baseline data on growth rates, changes in growth with age and size, age at maturity, and age-specific survival of this unusual insular Arboreal Salamander population. Here, we report on data from 2006 to 2010. MATERIALS AND METHODS Study Area.—Southeast Farallon Island (37u429N, 123u009W) is located 44 km west of San Francisco, California, USA. Comprising 48 ha, it is an elevated portion of a granitic submarine ridge running southwest from Point Reyes (Hanna, 1951). The shoreline is deeply cut by surge channels. The upland portion of the island is a series of rocky crags, some with sheer cliffs dropping into the sea on one or two sides. Along the southwest side there is a broad marine terrace approximately 15 m above sea level. On the lower talus slopes and level terrace, guano-enriched soil is well-developed between rocks. Burrows of seabirds (petrels and auklets) occur over nearly the entire island and, together with the many rocks and crevices, provide abundant cover for salamanders. The dominant vegetation is the herbaceous annual maritime goldfields (Lasthenia maritima), although in some areas nearly pure stands of dense, low, invasive annual grasses (Hordeum sp., Bromus spp., Poa sp.) are found. Temperature is moderate due to oceanic influence (1971–2009: mean 5 12.9uC, SD 5 1.6), with a Mediterranean climate of winter rains (1971–2009: mean 5 49.1 cm, SD 5 18.2) and dry but foggy summers and autumns (PRBO, unpublished data). The islands contain no standing or running fresh water with the exception of puddles and seepage areas during winter and spring (Anderson, 1960). During the summer and fall, the island becomes very dry and its appearance is almost desert-like. Salamander Capture and Measurement.—Arboreal Salamanders are primarily nocturnal, foraging for small invertebrates such as spiders, beetles, isopods, larval lepidoptera, ants, sow bugs, caterpillars, and centipedes on the ground or on the trunks of trees (Stebbins, 1951; Holland and Goodman, 1998). During the day, they remain under rocks, boards, bark, and decaying logs; inside decaying stumps and logs; in Woodrat houses and rodent burrows; and in stone walls and crevices, making them easily captured using cover objects. This long-term monitoring study was initiated during the rain year 2007 with the placement of 106 cover objects on Journal of Herpetology hpet-46-01-12.3d 10/12/11 04:22:09 1 Cust # MS10-282R 2 Corresponding Author. E-mail: derek.e.lee@dartmouth.edu 3 Present address: Wild Nature Institute, PO Box 165, Hanover, New Hampshire 03755 USA DOI: 10.1670/10-282 Journal of Herpetology, Vol. 46, No. 1, pp. 000–000, 2012 Copyright 2012 Society for the Study of Amphibians and Reptiles