Long-tailed Salamander, Dark-sided Salamander
© 2008 John White (1 of 58)
Country distribution from AmphibiaWeb's database: United States
Can you confirm these amateur observations of Eurycea longicauda?
Eurycea longicauda (Green, 1818)
Travis J. Ryan1
1. Historical versus Current Distribution. Long-tailed salamanders (Eurycea longicauda) are distributed throughout the Ozark Highlands, the Appalachian Highlands, and the Ohio River Valley. There is a narrow connection between the Ozarks and the rest of their range through southern Illinois and western Kentucky. Two subspecies, dark-sided salamanders (E. l. melanopleura) and long-tailed salamanders (E. l. longicauda), are recognized. Dark-sided salamanders are associated with the Ozark Highlands and are distributed from eastern Oklahoma and extreme southeastern Nebraska into central and eastern Missouri. Long-tailed salamanders range in a narrow band from southeastern Missouri through extreme southern Illinois, throughout most of Kentucky, central and western Tennessee, extreme northeastern Mississippi, northern Alabama, northern Georgia, extreme southwestern and northwestern North Carolina, western Virginia, West Virginia, Maryland, Pennsylvania, southern New York, and in the north from extreme eastern Illinois, west through southern Indiana, and into southern and eastern Ohio. Locally, distribution is somewhat dependant on the availability of suitable habitats.
Long-tailed salamanders frequently are associated with caves, mines, and shale and limestone creek beds. They have a bi-phasic life cycle; aquatic habitats are necessary for breeding and embryonic/larval development, while terrestrial habitats, especially forests surrounding these aquatic habitats, support post-metamorphic individuals. Populations undoubtedly have been lost due to factors such as habitat loss, acid drainage from coal mining, and clearcutting. However, as with most other wide-ranging, stream-dwelling plethodontids, there are no robust distributional studies that document changes in gross distribution.
2. Historical versus Current Abundance. Long-tailed salamanders can be locally abundant, with densities exceeding 10 adults/m2 (Mohr, 1944; Guttman, 1989; T.J.R., unpublished data). No clear long-term population studies (c.f., Semlitsch et al., 1988) have been published, obfuscating any differences between historical and current local population sizes.
3. Life History Features. The main aspects of the life history of long-tailed salamanders are typical of the lineage (i.e., subfamily Plethodontinae, tribe Hemidactyinii; Ryan and Bruce, 2000), and given the fairly broad distribution, there is relatively little variation in the pattern between subspecies or otherwise across the range.
A. Breeding. Oviposition is aquatic, as in all other Eurycea, and presumably courtship is aquatic as well. There are no published accounts of complete courtship encounters. One field observation (Cooper, 1960) mentions head-rubbing behavior, typical of plethodontids. There is only anecdotal evidence that females brood their clutches (Franz, 1964). Petranka (1998) speculated that the lone observation of brooding instead may well have been the lone observation of ovipositioning.
i. Breeding migrations. Adults and juveniles first become active above the surface in mid spring (Anderson and Martino, 1966; Minton, 2001). At this time they become more prominent at the water/land interface. Courtship, however, may not occur until much later in the year. Cooper’s (1960) field observation was made in October, and Ireland’s (1974) analyses of reproductive tract gross morphology indicated that the bulk of breeding activity occurs in late fall to early spring. Thus, while there may be a mid spring migration, it apparently is more connected with foraging and general surface activity than breeding per se.
ii. Breeding habitat. Egg laying occurs from late autumn to early spring, depending on latitude and altitude (Hutchison, 1956; Rossman, 1960; Anderson and Martino, 1966; Minton, 1972, 2001; Guttman, 1989) and also on temporal availability of suitable aquatic habitats. Eggs have been found in mid autumn (November; Franz, 1964), late winter (March; Ireland, 1974), and in between (January; Mohr, 1943).
B. Eggs. Egg size is typical for the genus, about 3 mm in diameter (Ryan and Bruce, 2000).
i. Egg deposition sites. Eggs generally are deposited in aquatic environments. Petranka (1998) notes that the discovery of eggs in the field is rare, but a trend is that oviposition is not only aquatic, but frequently subterranean as well (e.g., in caves, mine shafts, and cisterns). Non-aquatic eggs most likely are encountered in areas of high and constant humidity. For example, Franz (1964) found eggs suspended from the roof of a cave near a subterranean stream. Eggs have been found attached to undersides of stones in running water (Mohr, 1943), a pattern more typical for the lineage.
ii. Clutch sizes. Females produce between 61–106 eggs (Hutchison, 1956; Minton, 2001), apparently on an annual basis (Ireland, 1976). The incubation period ranges from 4–12 wk (Mohr, 1943; Ireland, 1974). Hatchlings are about 10 mm SVL (Hutchison, 1956; Anderson and Martino, 1966; Ireland, 1974). There is some discrepancy between the number of mature follicles in oviducal egg counts (Hutchison, 1956) and the number of eggs encountered in the field, indicating that a female may split her ovarian compliment among several clutches. This would be consistent with the apparent absence of brooding (see above).
i. Length of larval stage. The larval period of long-tailed salamanders is about 6 mo, but overwintering (with metamorphosis occurring at 12 mo post hatching) occurs in some populations. In New Jersey populations, metamorphosis occurs after a 2–2.5 mo larval period and at a size of about 20 mm SVL (Anderson and Martino, 1966). Larvae taken in February in Arkansas measure 10 mm SVL and grow rapidly, up to 6 mm/mo during spring and summer, arriving at metamorphosis in 5–7 mo and at 23–28 mm SVL (Ireland, 1976). A similar pattern was recorded by Rudolph (1978) in Oklahoma populations—hatching at about 10 mm SVL, metamorphosis at 25–32 mm SVL after 4–7 mo. In Rudolph’s populations, however, some portion of each cohort was observed to overwinter and metamorphose the following spring. He argues that overwintering is a response to lower invertebrate densities, and thus lower growth potentials, at the mouths of caves. There are reports of some populations requiring 2 yr for larval development (Smith, 1961, cited in Johnson, 1992).
ii. Larval requirements.
a. Food. Larvae ingest a variety of aquatic invertebrates, including ostracods, copepods, snails, and isopods, as well as insects such as dipteran and ephemeropteran larvae, and coleopterans (Rudolph, 1978).
b. Cover. Larvae most frequently are found beneath stones, limbs, and vegetation (rotting and emergent) in streams and ponds (Anderson and Martino, 1966; Petranka, 1998). Larvae may be active above cover objects and in the open at night (Petranka, 1998) and occasionally even in the middle of the day (T.J.R. and C.C., personal observations).
iii. Larval polymorphisms. None.
iv. Features of metamorphosis. Populations frequently breed in temporally variable aquatic habitats, such as classic Ambystoma-type temporary ponds (Anderson and Martino, 1966) and spring-fed intermittent streams in the Ozarks (Rudolph, 1978) and central Missouri (T.J.R., personal observations), and thus are subject to the pressure of completing metamorphosis prior to the completion of pond (or stream) drying. Obviously, overwintering is dependent on the persistence of suitable aquatic habitat throughout the year and is not possible in these ephemeral habitats.
v. Post-metamorphic migrations. Migrations of post-metamorphic juveniles are typically diffuse, with individuals gradually moving farther from the water’s edge as time passes, but Franz and Harris (1965) report a mass migration of post-metamorphic animals from a Maryland population.
vi. Neoteny. Perennibranchism is not known in long-tailed salamanders; the species is sympatric with a pair of perennibranchiate congeners, Oklahoma salamanders (E. tynerensis) and many-ribbed salamanders (E. multiplicata; being perennibranchiate in some populations). The coincidence of their ranges indicates that long-tailed salamanders (at least members of the subspecies E. l. melanopleura) live in habitats that may favor perennibranchism, but long-tailed salamanders apparently lack the phenotypic plasticity in the timing of metamorphosis and maturation to adopt a neotenic life history pattern.
D. Juvenile Habitat. In New Jersey, post-metamorphic juveniles can be abundant near pond edges immediately following metamorphosis, taking refuge under rocks, fallen tree trunks, and even beneath tree bark (Anderson and Martino, 1966), and this seems to be a standard pattern (Petranka, 1998). In general, juveniles are found closer to the water than are adults.
E. Adult Habitat. Adults are mainly terrestrial, found in and beneath old rotting logs and under stones. They are commonly found in crevices of shale and beneath stones and rock fragments near the margins of streams. Adults freely enter water and swim with ease. As with some other members of the genus Eurycea, they will enter caves. Adults emerge to feed on humid and rainy nights, where they are most active during the first few hours after dark (Hutchison, 1958; Smith, 1961; see also Petranka, 1998). Anderson and Martino (1966) found reduced densities surrounding permanent streams compared with populations surrounding temporary wetlands.
F. Home Range Size. Unknown. Adults can cover a considerable distance over the course of the year (≥ 100 m to and from the breeding habitat), but how much of this is considered “home range” is not clear, and it is made even less clear by the suggestion that many juveniles and adults spend a great deal of time underground.
G. Territories. Adults frequently are found in large aggregations. For example, Mohr (1944) found over 300 adults near the rear of a mine shaft, and Guttman (1989) found 80 animals underneath a limestone slab and 23 adults under a 4-m long log (see also Petranka, 1998). No territorial behavior was evident (S.A. Perrill, personal communication) when Indiana long-tailed salamanders were tested under protocols that have demonstrated territoriality in numerous other plethodontids (Jaeger and Marks, 1993). Territoriality is absent in three-lined salamanders (E. guttolineata; Jaeger, 1988), the sister species to long-tailed salamanders.
H. Aestivation/Avoiding Dessication. Aestivation is unknown.
I. Seasonal Migrations. Adults exhibit marked seasonal patterns in habitat use. During periods of heavy rains, adults will migrate uphill to slopes. Adults are known to migrate into and out of caves and mineshafts. Mohr (1944) found that large numbers of (300+) adults aggregate in a mineshaft for about 8 mo of the year, beginning in August–September and emerging again in April–May. Because hatchling larvae were detected in the ponds prior to notable surface activity, Anderson and Martino (1966) speculated that the breeding migrations may be subterranean, or that eggs are deposited in subsurface waters. This notwithstanding, they found surface activity begins in April, and by May most adults were within 6 m (20 ft) of the breeding ponds.
J. Torpor (Hibernation). Juveniles and adults migrate to underground retreats in forests in October and emerge to breed in April to early May. Whether or not this subterranean period is marked by inactivity is unclear.
K. Interspecific Associations/Exclusions. Long-tailed salamanders are rarely the only plethodontid salamanders at a particular site. For example, they are known to exist in close association with cave salamanders (E. lucifuga) in the Ridge and Valley province in western Virginia and eastern Tennessee and Kentucky (Hutchison, 1956, 1958); in eastern Oklahoma they are also found with congeneric many-ribbed salamanders and Oklahoma salamanders, but also grotto salamanders (Typhlotriton spelaeus, Rudolph, 1978); and in Indiana they are found syntopically with E. cirrigera (T.J.R. and C.C., unpublished data). Furthermore, when breeding in temporary ponds, larvae may interact with members of this pond-dwelling salamander guild, such as marbled salamanders (Ambystoma opacum), Jefferson salamanders (A. jeffersonianum), spotted salamanders (A. maculatum), and eastern newts (Notophthalmus viridescens; Anderson and Martino, 1966). Some of these potential interactions appear to be ecologically important, others appear benign.
As larvae in ephemeral ponds, long-tailed salamanders and marbled salamanders are the first to appear (Anderson and Martino, 1966). Marbled salamanders are fall breeders and are likely well established by the time long-tailed salamander hatchlings become active in the spring. Furthermore, marbled salamander larvae can be important predators on and/or competitors with other larval salamanders (e.g., Boone et al., 2002). Perhaps the lower density of long-tailed salamanders near streams as opposed to ponds (see above) is a response to avoiding competition from stream-dwelling plethodontids in the region (e.g., northern two-lined salamanders [E. bislineata], northern dusky salamanders [Desmognathus fuscus], and red salamanders [Pseudotriton ruber]). However, the larvae of long-tailed salamanders and southern two-lined salamanders (E. cirrigera) are found syntopically in some limestone creeks in southern Indiana (T.J.R. and C.C., unpublished data) in a manner analogous to their respective southern Appalachian sister species, three-lined salamanders and Blue Ridge two-lined salamanders (E. wilderae). The nature of potential competitive interactions has not been resolved.
Long-tailed salamander larvae appear to be competitive equals with larval cave salamanders (Wooley, 1971; Rudolph, 1978; see also Hutchison, 1956, 1958). Rudolph’s (1978) study of larval plethodontid community ecology indicates that long-tailed salamanders are not equal to other species, however. Both long-tailed salamanders and cave salamanders inhabit waters at the mouths of streams with subterranean origins and as far downstream as the stream’s hydrological stability permits (the likelihood of stream failure increases with distance from the stream origin). However, both species are displaced downstream when the cave-adapted grotto salamanders are present. Also, the diets of long-tailed salamanders and cave salamanders were more similar to each other than to other species (e.g., Oklahoma salamanders and three-ribbed salamanders) in field enclosures.
L. Age/Size at Reproductive Maturity. Long-tailed salamanders mature about 1–2 yr after metamorphosis (Ladd, 1947; Anderson and Martino, 1966; Ireland, 1974). In New Jersey, males mature when they reach about 43 mm SVL and females at 46 mm SVL, almost uniformly at 2 yr post hatching. Dark-sided salamanders in Arkansas mature at smaller sizes (31–43 mm SVL for males, 33–43 mm SVL for females) and as much as a year earlier than New Jersey populations (Ireland, 1974).
M. Longevity. Unknown.
N. Feeding Behavior. Adults feed on a wide variety of invertebrate prey. Specifically, Anderson and Martino (1966) documented annelids, isopods, diplopodans, chilipodans, arachnids (pseudoscorpions, spiders, phalangids, mites, and ticks), and various insects such as homopterans, coleopterans, dipterans, hymenopterans, lepidopterans, thysanurans, and orthopterans in the diet in their New Jersey populations. Hutchison (1958) found long-tailed salamanders in Virginia caves eat primarily dipterans, orthopterans, and coleopterans. A diet analysis of an Indiana population included > 20 types of invertebrates, with isopods, areneans, dipterans, coleopoterans, and colembollans being most numerous. Collectively, these reports indicate that long-tailed salamanders are invertebrate generalists; variations across adult habitats (e.g., caves versus forests) and within habitats across seasons produce different opportunities for feeding.
O. Predators. Larvae are preyed upon by sculpins (Cottus sp.) and sunfishes (Lepomis sp.; Rudolph, 1978).
P. Anti-Predator Mechanisms. This aspect of the long-tailed salamanders’ biology has not been studied rigorously, but individuals discovered in the field have displayed the classic defensive posture with an elevated tail (T.J.R., personal observations). The tail autotomizes readily when handled; additionally, long-tailed salamanders are quick, bolting for cover when disturbed (Johnson, 1992).
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. Long-tailed salamanders can be locally abundant, but populations have undoubtedly been lost due to habitat loss, effects of coal mining, and clearcutting. However, as with most other wide-ranging, stream-dwelling plethodontids, there are no robust distributional studies that document changes in gross distribution. Long-tailed salamanders are listed as Threatened in Kansas and New Jersey (Levell, 1997), and a Species of Special Concern in North Carolina.
1Travis J. Ryan
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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