Aneides vagrans Wake and Jackman, 1998
Nancy L. Staub1
David B. Wake2
1. Historical versus Current Distribution1. Wandering salamanders (Aneides vagrans) have an unusual distribution. They are found in the coastal forests of northern California and in British Columbia. They are not found in either Oregon or Washington (Jackman, 1999 ). The distribution of wandering salamanders in California extends from northern Siskiyou and Del Norte counties, south through extreme western Trinity, Humboldt, and Mendocino counties in an increasingly narrow coastal strip to the vicinity of Stewart's Point, northwestern Sonoma County. In British Columbia, wandering salamanders are widespread on Vancouver Island and on neighboring islands and occur in a small area of mainland British Columbia (Green and Campbell, 1984). Jackman (1999 ) argues that the British Columbia populations are derived from human-mediated introductions from California during the mid to late nineteenth century. In particular, genetic and historical evidence suggests that wandering salamanders were introduced to British Columbia from California in shipments of tan oak (Lithocarpus densiflorus) bark, used extensively in the tanning of leather at that time (Jackman, 1999 ).
The California populations now assigned to A. vagrans previously were considered to be A. ferreus (clouded salamanders) but have been reassigned based on allozyme, mitochondrial DNA, and karyotypic evidence (Sessions and Kezer, 1987; Jackman, 1999 ), Wake and Jackman, 1999 ). Nearly all of the literature dealing with A. ferreus from California and British Columbia refers instead to A. vagrans.
Studies of salamander abundance in different forest types and stages in Oregon and northwestern California (includes both A. ferreus and A. vagrans) show that this species has higher densities in older forests (Welsh and Lind, 1991). In British Columbia, wandering salamanders are found in microhabitats typical of clouded salamanders—in cavities of decaying logs and stumps or beneath loose bark (Stelmock and Harestad, 1979). In contrast to studies on clouded salamanders that showed that logging is detrimental to salamander abundance (Corn and Bury, 1991; Butts and McComb, 2000), forest harvesting did not appear to have long- term effects on the abundance of wandering salamanders (Stelmock and Harestad, 1979). Stelmock and Harestad (1979) found that in British Columbia, old-growth forest and regenerating conifer seral stages were equally favorable habitats for the wandering salamander, although their sample sizes of collected salamanders were small. It has not yet been determined whether the persistence of wandering salamanders in logged areas in British Columbia reflects a difference in moisture regimes between the habitats, a difference in logging practices and the amount of coarse woody debris left behind, an artifact of small sample sizes, or a difference in salamander biology.
Populations have certainly been lost due to forestry management practices and to urban sprawl.
2. Historical versus Current Abundance. Populations of the clouded salamander associated with post-logged areas eventually decline, and Corn and Bury (1991) doubt that they can survive in areas where forests are intensively managed on short rotation cycles because of the severe reduction in moisture conditions and in the amount of large woody debris. Presumably this reasoning holds true for wandering salamanders as well (although see "Historical and Current Distribution" above). Ironically, wandering salamanders now have a much wider distribution than in the past as a result of their introduction into coastal British Columbia, where they apparently rapidly expanded their range so that they now occur widely on Vancouver Island and many neighboring islands and have been found on the mainland (Green and Campbell, 1984).
3. Life History Features.
A. Breeding. Reproduction is terrestrial. Two albino specimens from two different egg clutches were found in Humboldt County, California (Houck, 1969).
i. Breeding migrations. Do not occur. Oviposition is thought to occur in spring or early summer in British Columbia (Stelmock and Harested, 1979).
ii. Breeding habitat. See "Brood sites" below.
i. Egg deposition sites. Egg clutches have been found under the bark of a rotting Douglas fir log (Wood, 1939; Dunn, 1942) and at the base of a tree limb 30–40 m above the forest floor (Welsh and Wilson, 1995). Davis (2003) has recently described the characteristics of three egg masses.
ii. Clutch size. Reported clutch sizes vary from 6–9 eggs (Dunn, 1942; Welsh and Wilson, 1995). The average for the ovarian complement of eggs is 18 (range 14–26, Stelmock and Harestad, 1979).
C. Direct Development.
i. Brood sites. The same as egg deposition sites.
ii. Parental care. If similar to the clouded salamander, variable. Clutches have been found without a parent in attendance (A. ferreus; Storm, 1947), with a female in attendance (A. vagrans; Dunn, 1942), and with both a male and a female in attendance (A. ferreus; Storm, 1947).
D. Juvenile Habitat. Brown (V., 1948) found three juveniles (presumably A. vagrans) under bark on a log. If habitat selection preferences are similar to the clouded salamander’s preferences, then juveniles prefer bark litter over rock or leaf litter; subadults prefer bark litter at higher temperatures (20 ˚C, 25 ˚C) and show no preference between rock or bark litter at lower temperatures (10 ˚C; McKenzie and Storm, 1970).
E. Adult Habitat. Adults are found associated with stumps and logs in Douglas fir forests (Welsh and Lind, 1988, 1991), under rocks (V. Brown, 1948; Jackman, 1999 ), under redwood slabs in redwood forests (Storer, 1925), and in the forest canopy (J.C. Spickler, personal communication). Wood (1939) found that adults have a tendency to be in, but not under, rotten logs. Bury and Martin (1973) found the wandering salamander associated with decaying stumps and logs in edge and open habitat (e.g., abandoned pastures, logging platforms in forest clearings), secondary forests, and in redwood forests. In coastal areas, Welsh and Lind (1988) captured more A. ferreus or A. vagrans in slightly younger forests than in the older forests, but inland, the opposite trend was evident. They suggest the variation is due to differences in moisture regimes between the different sites. In general, A. ferreus or A. vagrans were found in the more mesic habitats. Recent work suggests that the wandering salamander inhabits the canopy of old-growth redwood forests year-round (J.C. Spickler, personal communication). In the canopy, salamanders have been found in humus accumulations in trunk crotches, on limbs, under bark, and in cracked and rotting wood of broken limbs and trunks. They have been found ≤ 87 m above ground; at some sites, the canopy salamanders can be abundant (J.C. Spickler, personal communication).
Jackman (1999 ) suggests that there may be a difference in habitat preference between clouded and wandering salamanders—in northwestern California clouded salamanders are commonly found associated with both decaying logs and rocky slopes, while wandering salamanders are almost exclusively found associated with decaying logs.
F. Home Range Size. Unknown.
G. Territories. Studies on wandering salamanders indirectly suggest that they may not be as aggressive as clouded salamanders; wandering salamanders do not use chemical signals in fecal pellets to delimit territory boundaries, as with other plethodontids (Ovaska and Davis, 1992).
H. Aestivation/Avoiding Dessication. Aestivation is unknown; animals likely avoid dessicating condition by seeking shelter under cover objects or in burrows.
I. Seasonal Migrations. Not known to occur.
J. Torpor (Hibernation). Not known to occur.
K. Interspecific Associations/Exclusions. Clouded and wandering salamanders overlap in a zone < 15 km wide in northwestern California. Jackman (1999 ) reports evidence of introgression, but clear hybrid individuals have not been found. Mitochondrial, allozyme, and karyotypic data distinguish the clouded from the wandering salamander (Sessions and Kezer, 1987; Jackman and Wake, 1999 ).
In California, the range of wandering salamanders also overlaps with its congeners, arboreal salamanders (A. lugubris) and black salamanders (A. flavipunctatus; Stebbins, 1985; Wake and Jackman, 1999 ).
L. Age/Size at Reproductive Maturity. Based on follicle size, Stelmock and Harestad (1979) suggest that females greater than 50 mm SVL are sexually mature. This size is slightly smaller than the data on clouded salamanders (McKenzie, 1970) that suggest that females first reproduce in their third year when they are approximately 55 mm SVL. McKenzie (1970) estimated that male clouded salamanders mature during their second year at lengths greater than 36 mm SVL.
M. Longevity. Unknown.
N. Feeding Behavior. As with most salamanders, the wandering salamander is a generalist feeder. In California, wandering salamanders have a diverse diet consisting primarily of hymenopterans (ants), coleopteran adults and larvae, isopods, and collembolans (Bury and Martin, 1973). In a population in British Columbia, hymenopterans (ants), coleopterans, and gastropods were significant prey items in terms of both frequency and prey volume (Stelmock and Harestad, 1979). Acarinians (mites) and collembolans had a high frequency of occurrence, but their contribution to total prey volume was slight (Stelmock and Harestad, 1979). Juveniles eat smaller prey than do adults (Stelmock and Harestad, 1979).
O. Predators. Poorly documented, but Petranka (1998) suggests predators of Aneides sp. include mammals, woodland birds, and snakes.
P. Anti-Predator Mechanisms. Several anti-predatory behaviors have been observed in the clouded or wandering salamander when individuals are startled or attacked: immobility, a defensive posture (raising the body and undulating the tail), and flipping around followed by immobility (Brodie, 1977). Skin secretions are thought to be noxious (Brodie, 1977).
Q. Diseases. Unknown.
R. Parasites. Infestation rates of the nematode Thelandros salamandrae are greater than 50% in wandering salamanders (Stelmock and Harestad, 1979). These nematodes infect the large intestine. There was no difference in infection rate between males and females. Small animals (< 30 mm SVL) had no parasites (Stelmock and Harestad, 1979).
4. Conservation. Wandering salamanders have higher densities in old-growth forests, and while populations certainly have been lost due to forestry management practices and urban sprawl, animals can be found at high densities in regenerating forest. Wandering salamanders now have a much wider distribution than in the past as a result of their introduction into coastal British Columbia.
1Nancy L. Staub
Spokane, Washington 99258
Museum of Vertebrate Zoology
3101 Valley Life Sciences Building #3160
University of California
Berkeley, California 94720
2David B. Wake
Museum of Vertebrate Zoology
3101 Valley Life Sciences Building #3160
University of California
Berkeley, California 94720-3160
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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