© 2001 Margaret S. Gunzburger (1 of 8)
Notophthalmus perstriatus Bishop, 1941(a)
C. Kenneth Dodd Jr.1
1. Historical versus Current Distribution. The range of striped newts (Notophthalmus perstriatus) extends from Screven, Jenkins, and Emanuel counties in Georgia, south to Orange, Osceola, and Seminole counties in central Florida, and west to Baker County, Georgia, and Wakulla and Leon counties in Florida (Dodd and LaClaire, 1995; Franz and Smith, 1995; Means and Means, 1998a; Stevenson et al., 1998; Johnson and Dwyer, 2000). Records for Santa Rosa and Glades counties, Florida, are in error (Franz and Smith, 1995). Striped newts appear to occur in two separate regions, one in the Florida Panhandle near Tallahassee (Means and Means, 1998b) and the adjacent Dougherty Plain of southwest Georgia (LaClaire et al., 1995), and a second in the east (populations associated with sand ridges and river terraces on the Atlantic Coastal Plain of southeastern Georgia into peninsular Florida). The hiatus between the Florida groups is roughly 125 km and between the Florida Panhandle and southwest Georgia populations, 100 km. However, it is not known whether these hiatuses represent real biogeographic separations or are artifacts of poor collection and/or habitat loss. Mitochondrial DNA sequences (cytochrome b) support the biogeographic scenario. A neighbor-joining tree revealed distinct western and eastern groups with no sharing of haplotypes between the two regions (Johnson, 2000).
In their review, Franz and Smith (1995) recorded 116 historical “observations” of striped newts from 20 Florida counties. They visited 30 of 40 identifiable historical locations and found striped newts at six ponds. They also added 21 new localities. All 27 localities were on public lands. Surveying ponds in the Munson Sand Hills in the Florida Panhandle, Means (2001b) found only 20 of 265 (7.5%) ponds containing larvae or adults of striped newts, adding 15 new ponds from Leon County to those surveyed by Franz and Smith (1995), all on public lands. However, only nine of these ponds proved to be breeding ponds with larvae. Also, Means and Means (1998b) surveyed 57 ponds in the Tallahassee Red Hills of panhandle Florida and the Tifton Uplands of adjacent southwestern Georgia, finding one pond on private land containing striped newts. This pond contained striped newts in 1969, but they were not found in 1977, and were probably extirpated because the pond had been deepened and stocked with game-fish. In Georgia, striped newts were reported historically from 11 general areas (treating Trail Ridge as one area). Dodd and LaClaire (1995) found newts at six sites, one of them new. Sites contained from one to a few nearby ponds inhabited by newts. On Trail Ridge, only one pond could be reconfirmed, although many ponds once contained newts in this region (Dodd, 1995c). One additional Georgia location has since been found (Stevenson et al., 1998). Of these seven sites, four are on public land, and one is on a private ecological reserve. At least one Georgia locality (in Ben Hill County) was destroyed in the 1950s. However, surveys in both states were hindered by poor locality data accompanying museum specimens and difficulty in locating historical sites because of the substantial land changes that have occurred since many of the early specimens were collected. Undoubtedly, many of the historical localities no longer exist.
The historical range of striped newts was probably similar to the current range. Because of extensive habitat modification, however, many populations likely have been lost. It is possible that new populations may be discovered. In that regard, Dodd and LaClaire (1995) suggested areas in Georgia that should be surveyed for this species. Based on habitat potential, Cox and Kautz (2000) listed several public land holdings that might support striped newts in Florida but need to be surveyed.
2. Historical versus Current Abundance. Striped newts may be extremely abundant at ponds, or ponds may contain only a few individuals. For example, Dodd (1993b) recorded 744 different striped newts in 1987 at a 0.16 ha-pond in north-central Florida, whereas Johnson (1998) marked about 2,400 striped newts at a nearby 0.2 ha-pond during a drift fence study in 1996–'97. In contrast, other surveys have recorded > 100 striped newts at breeding ponds despite intensive and repeated sampling (Cash, 1994; Means and Means, 1997; Greenberg, 1998; D. Franz, personal communication; C.K.D., S.A.J., unpublished data). The reasons for this disparity are unknown. Both extremes in abundance are found on protected sites, however, and it is likely that considerable variation annually exists from site-to-site depending on demographic (metapopulation structuring) and environmental conditions. Presumably, similar variation affected striped newt populations historically, although no historical data are available on abundance.
3. Life History Features. The life history and biology of this species are summarized by Petranka (1998) and Johnson (1998, in press a). Life history stages include egg, larval, eft, and either transformed or neotenic adults.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Striped newts migrate to breeding ponds in fall, winter, and/or spring, depending on weather conditions. Most substantial migrations take place from November–March, although immigration and emigration can take place during nearly any month, except during hot, dry periods (Dodd, 1993b; Means and Means, 1997; Johnson, 1998, 2002). Immigration is correlated with heavy rains that result in pond filling, whereas emigration occurs in response to pond drying (Dodd, 1993b) and metamorphosis (Johnson, 2001, 2002). Dodd and LaClaire (1995) found small larvae in Georgia breeding ponds in May, and Christman and Means (1992), Means et al. (1994), Johnson (1998) and Means (2001b) noted the presence of larvae from April–December. Striped newts exhibit a high degree of phenotypic plasticity in the timing of their breeding migrations, which allows individuals to take advantage of variation in seasonal and annual rainfall.
Migrations do not appear to follow corridors or topography, at least in the few studies that have examined travel routes (Dodd and Cade, 1998; Johnson, 2001; D.B.M., unpublished data). At the same time, migration is directionally non-random, reflecting the distribution of suitable habitat surrounding the pond. Patterns of emigration and immigration may vary annually and by sex.
Once at a pond, adults appear to spend several weeks fattening themselves in preparation for breeding; adults entering the pond often are thin and in poor body condition.
ii. Breeding habitat. Breeding occurs in shallow temporary ponds associated with well-drained sands (sandhills [“high pine”], scrubby flatwoods, and scrub communities). In the high forests, ponds may or may not contain uniformly distributed emergent vegetation, although striped newts seem to prefer ponds with substantial amounts of vegetation, particularly grasses (Panicum spp.), surrounding the pond margins and Eleocharis spp. in the water. Floating mats of Sphagnum occur at some sites. Overstory trees (cypress [Taxodium sp.] and black gum [Nyssa sp.]) may or may not be evenly spaced throughout the pond. Breeding also has been recorded in a few human-created temporary wetlands, such as borrow pits and drainage ditches. Although striped newts are found most often in temporary ponds, they occur in at least one permanent, isolated pond in Ocala National Forest. They do not occur in ponds with predatory fishes.
i. Egg deposition sites. Eggs are deposited singly in vegetation, presumably in the shallow water margins of ponds. Although they are deposited one at a time, they may occur in clumps of 2–5 eggs. The female uses her back legs to wrap protective vegetation around the egg.
ii. Clutch size. Unknown.
C. Larvae/Metamorphosis. Larvae hatch at about 8 mm TL (Mecham and Hellman, 1952).
i. Length of larval stage. Larvae have been found from April–December (Christman and Means, 1992; Means et al., 1994; Means, 2001b; S.A.J., unpublished data). The length of the larval period probably varies depending on hydroperiod, temperature, and food resources. Dodd (1993b) reported successful metamorphosis at a pond with a hydroperiod of 139 d. At another pond, Johnson (2002) estimated that immature larvae had a larval period of about 6 mo, and mature larvae (i.e., paedotypic individuals; see "Neoteny" below) remained aquatic for about 18 mo. Johnson (2001, 2002) also observed four distinct periods of newt metamorphosis during a 2-yr study at this pond. Two of these metamorphic events occurred during autumn to early winter, and the other two from late spring to summer. The pond held > 75 cm of water throughout the 2-yr period. Means (2001b) has noted the same biphasic emergence of striped newts in panhandle populations, but sexually mature larvae in his pond remained aquatic for only about 15 mo.
ii. Larval requirements.
a. Food. Unknown. As with adults, larvae probably eat any small invertebrates that they can catch. In captivity, larvae eat mosquito larvae, chironomid larvae, fairy shrimps, clam shrimps, and amphipods (Hyalella azteca; D.B.M., S.A.J., unpublished data).
b. Cover. Larvae presumably hide in dense vegetation in shallow water (≤ 60 cm deep), but nothing is known of their specific cover requirements.
iii. Larval polymorphisms. No larval polymorphisms are known.
iv. Features of metamorphosis. Dodd (1993b) found transformed larvae as small as 18 mm SVL in Florida, although most were 22–25 mm. In a nearby Florida pond, larvae transformed at 20–30 mm (Johnson, 1999).
v. Post-metamorphic migrations. Transformed individuals presumably move to habitats similar to those used by adults. Emigration occurs from summer throughout autumn, depending on the timing of metamorphosis. Emigration occurs both singly and in mass groups. It is not known how long it takes recently transformed individuals to move from breeding ponds to suitable terrestrial habitat. In a Florida Panhandle pond, larvae transformed from slightly < 20 mm SVL during pond dry-down, to 20–30 mm for sexually immature larvae, and from 30–42 mm for paedotypic individuals (Means, 2001b).
vi. Neoteny. Paedomorphosis has been observed at numerous striped newt breeding ponds. The expression of the paedomorphic phenotype appears to have a substantial genetic component and is likely regulated by a suite of genes (Johnson, 2001). Johnson (unpublished data) found that about 25% of all larvae in one pond became paedomorphic in each of two consecutive years. In a pond in the Ocala National Forest, the vast majority of (if not all) larvae appear to become paedomorphic each year. Although environmental conditions (e.g., pond hydroperiod) certainly affect paedogenesis; food availability, and thus growth rate, did not have a major impact on paedogenesis of newts from a north Florida pond (Johnson, 2001). Paedomorphic individuals can reproduce at about 1 yr of age, and after reproduction is complete, they initiate metamorphosis and migrate from the breeding pond into the surrounding uplands (Johnson, in press a). This occurs even if the breeding pond does not dry. If ponds dry, however, observations at several sites show that larviform adults can transform and assume a terrestrial phenotype.
D. Juvenile Habitat. Presumably, juveniles occupy similar terrestrial habitats as adults. According to Petranka (1998) efts generally resemble adults, but unlike adults have a dull orange dorsal background color, rougher skin, and a rounder tail.
E. Adult Habitat. Adults sometimes are found at considerable distances (to > 700 m) from the nearest breeding pond (Dodd, 1996). Adults require shelter from the harsh conditions (heat, cold, and drought) that are present in their environment. Presumably, they stay under cover in subterranean refugia. Occasionally, striped newts are found under logs. The original sandhills vegetation was longleaf pine (Pinus palustris) savanna with a rich groundcover of grasses and forbs. A turkey oak (Quercus laevis) midstory was suppressed by frequent ground fires in the early lightning season, April–July.
Based on captures at drift fences, Johnson (1999) estimated that 18% of the population of newts at one breeding pond dispersed in excess of 500 m from the pond. Adults require shelter from the harsh environmental conditions (heat, cold, and drought) that are present in their environment. Presumably, they stay under cover in subterranean refugia.
F. Home Range Size. Nothing known.
G. Territories. It is unlikely that adults possess defended terrestrial territories. Adult males vie for females during the aquatic breeding season and attempt to maneuver them in the direction of their spermatophores, but defended territories are unknown.
H. Aestivation/Avoiding Dessication. Nothing known. However, striped newts are active year-round as long as conditions are appropriate (Dodd, 1993b; Means and Means, 1997; Johnson, 2001, 2002). Dodd (1993b) found that the least activity was in August, one of the hottest months throughout the range of striped newts. However, Johnson (2001, 2002) caught hundreds of efts leaving a pond in August 1998.
I. Seasonal Migrations. After breeding, adults return to terrestrial refugia. The timing of return migrations varies depending on weather and pond conditions. Usually, newts leave the ponds as water levels fall. This occurs from late spring to early summer, depending on rainfall. There is a great degree of variation as to when emigration occurs, however.
J. Torpor (Hibernation). See "Aestivation/Avoiding Dessication" above.
K. Interspecific Associations/Exclusions. In panhandle Florida and occasionally elsewhere, striped newts are syntopic with eastern newts (Notophthalmus viridescens), mole salamanders (Ambystoma talpoideum), and dwarf salamanders (Eurycea quadridigitata; Means et al., 1994; Means, 1996b; Means and Means, in press). The nature of the interaction between striped newts, eastern newts, and dwarf salamanders is unknown, but predation on striped newts by mole salamanders is highly likely (D.B.M., unpublished data). Striped newts do not breed in ponds inhabited by predatory fish.
L. Age/Size at Reproductive Maturity. The smallest reproductively mature striped newts entering breeding ponds are 28–29 mm SVL. Sexual size dimorphism is not apparent in size at first reproduction, although in general, males are slightly smaller and weigh less than females (Dodd, 1993b). Petranka (1998) suggests that striped newts require 8–24 mo to reach sexual maturity, the same as eastern newts (Johnson, 2001, 2002). Attempts to age striped newts using skeletochronology have proven unsuccessful (G. Zug, personal communication).
M. Longevity. Grogan and P.G. Bystrak (1973) reported that a striped newt lived at least 11 yr, 2 mo in captivity, but given the large size of the specimen (105 mm TL) and the fact that it was purchased in Maryland (well out of the range of striped newts), we question their species identification. Other Notophthalmus live 12–15 yr in the wild (Forester and Likens, 1991). Dodd (1993b) speculated that striped newts lived a long time because of the great variation in reproductive uncertainty due to stochastic environmental conditions.
N. Feeding Behavior. Metamorphosed striped newts are opportunistic feeders taking a wide variety of prey, including frog eggs, worms, snails, fairy shrimp, spiders, and insects (larvae and adults). In Florida, the greatest number of prey items were benthic dipteran larvae (Christman and Franz, 1973). Christman and Franz (1973) suggested that striped newts were not solely visually oriented predators, but probably used smell to direct their attention toward certain potential food sources (such as frog eggs). These observations were made on aquatic adults in breeding ponds, but nothing is known about food habits during the long terrestrial stage.
O. Predators. Because of toxic skin secretions, probably few predators molest adult striped newts. Larvae undoubtedly fall prey to a host of aquatic predators because of their small size.
P. Anti-Predator Mechanisms. The anti-predator mechanisms of striped newts have not been investigated. Other members of the genus Notophthalmus have skin glands that produce a potent neurotoxin called tarichatoxin; presumably striped newts do likewise. Toxins may be present in larvae, efts, and aquatic/terrestrial adults to various degrees. Of course, toxins may function not only in defense against predators, but also against external parasites. When molested, adults occasionally assume an “unken” posture, although it is not as intense as in eastern newts.
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. Although striped newts are not protected by Federal statutes, the U.S. Fish and Wildlife Service is concerned about their biological status and considers the species as Under Review. Striped newts are listed as Rare in Georgia because of the small number of known localities within the state (Jensen, 1999b). The Florida Natural Areas Inventory considers striped newts as Imperiled in Florida, and the Florida Committee on Rare and Endangered Plants and Animals lists the species as Rare. Although Cox and Kautz (2000) discussed the status and biological requirements of the striped newt in Florida, they are not protected in the state and have no legal protected status. Striped newts have declined substantially throughout their range because of direct habitat loss and habitat degradation (e.g., fire suppression, silvicultural practices, pond drainage, and fish introductions; Dodd and LaClaire, 1995; Franz and Smith, 1995; S.A.J., unpublished data). Presently, they persist at about 15 isolated locations throughout their range, and the majority of these locations are on public property.
Johnson (2001), Dodd and LaClaire (1995), Means (2001), Christman and Means (1992), and Means and Means (in press) provided suggestions for conserving striped newts. In general, the most effective conservation and management plan is one that will closely mimic historical conditions, and therefore facilitate striped newt metapopulation function on a landscape scale (Means and Means, in press). Breeding ponds must be protected, and a large area of suitable upland core habitat should be protected and managed around the ponds, thus maintaining connectivity among the breeding sites. The best upland habitats are longleaf pine forest with native groundcover. Silvicultural forests of slash, loblolly, and sand pines are not suitable (Means and Means, in press). Prescribed fire is essential to proper management of uplands and wetlands. Furthermore, mechanical disturbance to native ground cover and soils, which is associated with most silvicultural practices, must be avoided. Striped newts should be regularly monitored at sites where they persist and surveys should be conducted in an attempt to locate additional breeding ponds. Sites on private property should be acquired by state or federal agencies or private conservation organizations, or protected through conservation easements that guarantee permission to manage the sites for striped newts (i.e., conduct prescribed burning).
1C. Kenneth Dodd Jr.
2D. Bruce Means
3Steve A. Johnson
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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