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Aneides lugubris (Hallowell, 1949)
Arboreal Salamander
Nancy L. Staub1
David
B. Wake2
1. Historical versus Current Distribution. Arboreal
salamanders (Aneides lugubris) occur in
coastal oak woodlands from northern California (Humboldt
County) to approximately Valle Santo Tomas, Baja California
del Norte, Mexico. Their range includes South Farallon,
Santa Catalina, Los Coronados, and Año Neuvo Islands (Lynch
and Wake, 1974; McPeak, 2000). In the foothills of the
Sierra Nevada, a geographically isolated cluster of
populations occurs in black oak and yellow pine forests
(Lynch and Wake, 1974). This group of populations is
genetically distinct from coastal populations (Jackman,
1993). The range of arboreal salamanders is similar to the
range of the oaks (Quercus agrifolia and
Q. wislizenii), presumably a consequence
of shared moisture and soil characteristics (Rosenthal,
1957). However, in southern California, arboreal
salamanders are frequently associated with sycamores
(Platanus racemosa) bordering seasonal
streams.
Populations have certainly been eliminated as coastal
California habitats have been developed, but the species
survives in many urbanized regions where adequate cover is
present.
2. Historical versus Current Abundance. Although
Arboreal salamanders remain common in many areas, in some
areas populations have declined in the past 20 yr (D.B.W.,
personal observations). Petranka (1998) suggests that large
oaks used for nesting and aestivation should be preserved.
The current decline of live oaks in California will have
negative effects on arboreal salamander populations.
3. Life History Features. Reproduction is terrestrial.
A. Breeding.
i. Breeding migrations. Breeding migrations do not
occur, but seasonal or daily vertical migrations into and
out of trees are possible.
ii. Breeding habitat. Unknown. During courtship a
courting male places his mental gland on the female's
dorsum and, in a succession of quick strokes, draws the
mental gland across the female's back (Arnold, 1977).
During this behavior, the male's large and monocuspid
premaxillary teeth may scratch the female's skin and enable
efficient delivery of mental gland pheromones to the
female's circulation.
B. Eggs. i. Egg deposition sites. Reported
oviposition sites include in decay holes of live oak trees
(most common), under rocks set deeply in the ground, in
logs, under surface cover objects (e.g., stone slabs,
flower box), and beneath the ground surface (Ritter and
Miller, 1899; Ritter, 1903; Storer, 1925). Egg clutches
have been found ≤ 9 m above ground in live oak trees
(Ritter, 1903). Most females oviposit in late spring or
early summer (Stebbins, 1951; Anderson, 1960).
ii. Clutch size. The number of eggs in a clutch varies
from 5 - 24 (Ritter, 1903; Storer, 1925; Stebbins, 1951),
with larger females producing more eggs (Anderson, 1960).
Ovarian counts range from 5 - 26 maturing oocytes
(Anderson, 1960). Females on densely populated islands tend
to produce fewer eggs than females in less dense mainland
populations (Anderson, 1960). Eggs are large, 7 - 9.5 mm in
diameter.
C. Direct Development.
i. Brood sites. The same as egg deposition sites.
ii. Parental care. Females are often found coiled
around the eggs; males are often in attendance as well
(Ritter and Miller, 1899; Ritter, 1903; Stebbins, 1951).
After an approximately 3 - 4-mo developmental period,
embryos hatch in August - September at between 26 and 32 mm
TL (Storer, 1925; Stebbins, 1951). Presumed family groups
may stay associated after hatching (Ritter, 1903).
D. Juvenile Habitat. Similar to that of adults.
E. Adult Habitat. Arboreal salamanders are found in a
variety of terrestrial and arboreal habitats, including
under rocks and woody surface cover, in decaying stumps and
logs, in decay holes in trees, and in rock crevices (Ritter
and Miller, 1899; Ritter, 1903; Storer, 1925; Miller, 1944;
Stebbins, 1951; Rosenthal, 1957; Anderson, 1960).
Climbing is facilitated by expanded tips of terminal
phalanges and large subdigital pads, as well as by the
prehensile tail of the arboreal salamander (Ritter and
Miller, 1889). Individuals have been found over 18 m above
ground in trees (Ritter and Miller, 1899; Ritter, 1903;
Stebbins, 1951). Arboreal salamanders can be found in
microhabitats that are drier than those of sympatric
salamanders (Storer, 1925; Cohen, 1952; Ray, 1958;
Anderson, 1960). This species is generally absent from
regions receiving < 25 mm of precipitation per year
(Rosenthal, 1957).
F. Home Range Size. Unknown.
G. Territories. Arboreal salamanders are well known for
their aggressive tendencies and weaponry. This species has
a suite of morphological features that enable a strong,
wound inflicting bite. The jaw muscles are hypertrophied,
the skull is heavily ossified with especially strong jaws,
and both juveniles and adults possess enlarged and
flattened, blade-like, monocuspid teeth (other
plethodontids possess weaker bicuspid teeth as juveniles;
Wake, 1966; Wake et al., 1983). In his description of
arboreal salamanders, Cope (1889) writes: "On the whole,
the physiognomy is not unlike that of a snapping tortoise."
Scarred individuals are often found in the field (Miller,
1944; N.L.S., personal observation), and Myers (1930b)
observed that salamanders housed in the same container bite
each others' tails. In a study of museum specimens, Staub
(1993) found that 15% of the examined individuals were
scarred, presumably from conspecific attacks. The frequency
of scarring did not differ significantly between males and
females (Staub, 1993).
H. Aestivation/Avoiding Dessication. Arboreal
salamanders are more tolerant of dry conditions than are
many species of salamanders and are often among the last
salamanders to retreat underground or into tree holes to
avoid desiccation (Miller, 1944; Cohen, 1952; Ray, 1958;
Petranka, 1998). This species has relatively low rates of
water loss compared to other salamanders, possibly due to
postural adaptations (curled body and tightly coiled tail)
and a rapid rate of water uptake (Cohen, 1952; Ray, 1958).
I. Seasonal Migrations. Not known to occur.
J. Torpor (Hibernation). Not known to occur.
K. Interspecific Associations/Exclusions. Arboreal
salamanders are syntopic with California slender
salamanders (Batrachoseps attenuatus),
wandering salamanders (A. vagrans), and
black salamanders (A. flavipunctatus) in
regions north of San Francisco Bay. Throughout most of the
rest of their range, arboreal salamanders occur in sympatry
with Ensatina and a number of species of
Batrachoseps. Ecological interactions between
these species are not well understood. Maiorana (1978a)
showed that there may be competition for food between
California slender salamanders and arboreal salamanders
when large prey are limited. When large prey items are not
limiting however, Lynch (1985) found broad dietary
differences between these two species arboreal salamanders
tend to eat a few, large bodied prey in addition to a
diverse assortment of other prey items. Arboreal
salamanders occasionally prey on Batrachoseps
(Storer, 1925; Miller, 1944).
L. Age/Size at Reproductive Maturity. Arboreal
salamanders are the largest species of Aneides;
mature individuals range in size from 65 - 100 mm SVL
(Lynch and Wake, 1974). Age-size relationships suggest that
3 yr are required to reach maturity (Anderson, 1960).
Anderson (1960) reported that the minimum size of sexual
maturity was 34 mm SVL for females, though this size seems
small for typical females reaching sexual maturity.
M. Longevity. Unknown.
N. Feeding Behavior. Arboreal salamanders are nocturnal
and feed most actively under moist/wet conditions. Adults
tend to feed on larger prey than juveniles, although Wake
et al. (1983) point out that arboreal salamanders of all
sizes take a range of prey items. The diet of arboreal
salamanders includes millipedes, annelids, snails, and
especially coleopterans, hymenopterans (ants), isopterans
(termites), isopods (sowbugs), chilopods (centipedes), and
lepidopterans (Miller, 1944; Zweifel, 1949; Bury and
Martin, 1973; Lynch, 1985). Miller (1944) suggests that
fungus is an important component of the diet, but other
authors have not confirmed this observation. Relative to
syntopic species, arboreal salamanders consume
disproportionately larger prey items than expected for
individuals of a given body size (Lynch, 1985), and
comparative data suggest that arboreal salamanders consume
numerous large-sized prey that other species are unable to
capture (Bury and Martin, 1973). The structural components
of the feeding apparatus are well developed (e.g., well
ossified skull; Wake et al., 1983). Despite the large jaws
and teeth, prey are typically captured by the tongue and
brought fully into the mouth, usually without contacting
the marginal dentition (personal observation).
O. Predators. Pacific rattlesnakes (Crotulus
viridis helleri) are known predators of
arboreal salamanders (Mahrdt and Banta, 1997), and a
California scrub jay (Aphelocoma
coerulescens) has been observed trying to eat a
juvenile arboreal salamander (Rubinoff, 1996).
P. Anti-Predator Mechanisms. Several anti-predatory
behaviors have been observed when individuals are startled
or attacked: a defensive posture (raising the body stiffly
off the ground; Cohen, 1952; Stebbins, 1951), squeaking
(Ritter and Miller, 1899; Storer, 1925), rapid movement and
jumping (Ritter and Miller, 1899), and biting (Ritter,
1903; Storer, 1925; Stebbins, 1951; Lynch, 1981). Arboreal
salamanders will bite terrestrial garter snakes
(Thamnophis elegans), and in some cases
the snakes can die from the inflicted wounds (Lynch, 1981).
Micturition, the act of voiding the bladder when startled,
is a novel putative antipredatory behavior that has been
documented for arboreal salamanders (Staub and Anderson,
2001).
Q. Diseases. Not reported.
R. Parasites. Two species of nematode
(Batracholandros salamandrae,
Oswaldocruzia pipiens) have been found in
arboreal salamanders (Schad, 1960; Goldberg et al., 1998c).
S. Comments. There are two geographically segregated
groups of chromosomally differentiated populations of
arboreal salamanders (Sessions and Kezer, 1987). These two
karyotypes intergrade in south and east-central Mendocino
County (Sessions and Kezer, 1987). Unpublished genetic
analyses (allozymes and mitochondrial DNA sequences) show
that the chromosomal units do not correlate with patterns
of genetic variation (Jackman, 1993). The Farallon Island
population is most similar genetically to the nearest
mainland population, not populations in the Gabilan
mountains to the south as suggested by Morafka (1976; see
also Jackman, 1993).
4. Conservation. The range of arboreal salamanders is
similar to the range of their oak habitat; oaks are used
for nesting and aestivation. The current decline of live
oaks in California will have negative effects on arboreal
salamander populations.
Populations of arboreal salamanders have certainly been
eliminated as coastal California habitats have been
developed, but the species survives in many urbanized
regions where adequate cover is present.
Nancy L. Staub1
Biology
Department
Gonzaga University
Spokane,
Washington 99258
staub@gonzaga.edu
And:
Museum of Vertebrate Zoology
3101
Valley Life Sciences Building #3160
University of
California
Berkeley, California 94720
David B. Wake2
Museum
of Vertebrate Zoology
3101 Valley Life Sciences
Building #3160
University of California
Berkeley, California 94720-3160
wakelab@uclink4.berkeley.edu
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 16 Dec 2024.
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