day or at night, or during a rainfall(Twitty, 1966). Stomach content analysisof terrestrial and aquatic adults revealedthat the diet consists of terrestrial organ-isms only, predominantly insects. Adultsapparently do not feed during their aquaticphase, though they will resume feedingif forced back onto land by winter floods(Packer, 1961). Aquatic adults maintainedin the lab also do not feed (Licht andBrown, 1967).

O. Predators. No predators have beenspecifically reported for red-bellied newts.However, Twitty (1966) reported that athis field station in Sonoma County, gartersnakes “brazenly stole” newts from stor-age containers as he and his assistantslooked on. Both red-bellied and rough-skinned newts occurred at the field sta-tion, but most of Twitty’s work there wason red-bellied newts, so presumably thisis the species to which he was referring.He did not identify the garter snakes tospecies, but most likely they were com-mon garter snakes (Thamnophis sirtalis),which are known to feed on rough-skinnednewts (see rough-skinned newt speciesaccount for references).

P. Anti-Predator Mechanisms. The anti-predator mechanisms of red-bellied newtsare similar to those described for rough-skinned newts: toxicity, aposematic col-oration, and defensive posturing. Ovarianeggs and embryos of red-bellied newtscontain high levels of tetrodotoxin (Mosheret al., 1964); all three species of Tarichashow similar levels of toxicity in this re-gard (Twitty, 1937; Brodie et al., 1974b).The skin of adult red-bellied newts alsocontains tetrodotoxin. The toxicity of theback skin of adult female red-bellied newtsis similar to that of California newts, butadult rough-skinned newts are consider-ably more toxic. Brodie et al. (1974b) esti-mated that 1,200–2,500 mice could bekilled by the skin of red-bellied newts (ascompared to approximately 25,000 micefor rough-skinned newts). Ovarian eggsand adult skin of red-bellied newts havesimilar toxicity levels. These high levels oftetrodotoxin render newts inedible tonearly all predators (Brodie, 1977). Ani-mals are dark-colored dorsally and brighttomato-red ventrally. The dark dorsum iscryptic against the forest floor. The defen-sive posture exposes the aposematic col-oration of the ventral surface. During theunken reflex, the tail and head are ele-vated vertically, revealing the bright redunderside of the chin and tail; at the sametime, toxic skin secretions are released.The defensive display varies somewhat de-pending on the state of the salamander orwith the intensity of stimulation: the lowintensity response is a U-shaped postureinvolving a vertical elevation of head andtail such that both point skyward. With ahigh intensity response, the head tips fur-ther back and the pelvis and hindlimbsare lifted off the substrate such that the

tip of the snout and the base of the tailalmost come into contact. The unken re-flex display is generally similar in allspecies of Taricha, but red-bellied newtsshow one striking variation in posture. In-stead of elevating the tail, sometimes thepelvis and hindlimbs remain in contactwith the ground, while the head, fore-limbs, and body are together lifted fromthe substrate; this variation in posturemay be a result of the longer tail of red-bellied newts counterbalancing the body(Brodie, 1977).

Q. Diseases. None reported.R. Parasites. None reported.

4. Conservation.The conservation status of red-belliednewts is uncertain, because no ecologicalstudies have been conducted on thisspecies for the last 35 yr or so. However,this species has a limited and somewhatspotty geographic distribution, and humanpopulation pressure has intensified con-siderably over much of its range. Specifi-cally, conversion of native forests andgrasslands to vineyards and subdivisionslikely poses a serious threat to red-belliednewts. For example, this change in landuse has led to the large-scale removal oftrees, resulting in the alteration of temper-ature, sediment load, and physical struc-ture of rivers and streams, such that theyare less hospitable to native anadromoussalmonid fishes (Giusti and Merenlender,2002). It is likely that this degradationof aquatic habitat has also negativelyimpacted aquatic-breeding salamanders,such as red-bellied newts. Removal oftrees also affects the microclimate of ter-restrial habitats, perhaps rendering themless suitable for terrestrial newts. Finally,increased vehicular traffic associated withhousing subdivisions undoubtedly has re-sulted in increased mortality of terrestrialnewts.

Taricha torosa Rathke, 1833CALI FOR N IA N EWT

Shawn R. Kuchta

1. Historical versus Current Distribution.Riemer (1958) conducted the first compre-hensive investigation of the distributionand systematics of the genus Tarichaand recognized 2 allopatric subspecies of T. torosa (California newts; Riemer, 1958):T. t. torosa (Coast Range newts) and T. t.sierrae (Sierra newts). Coast Range newtsare distributed from central MendocinoCounty in northwestern California souththrough the Coast Ranges to BoulderCreek on the western slope of the penin-sular ranges in San Diego County (Steb-bins, 1985). Coast Range newts are foundfrom sea level to at least 1,280 m on Mt.Hamilton, Santa Clara County, California(Stebbins, 1959). The southernmost lo-calities in San Diego County compose a

geographic isolate (Stebbins, 1985; Jen-nings and Hayes, 1994a), and were oncerecognized as a distinct subspecies (T. t.klauberi : Wolterstorff, 1935; Stejneger andBarbour, 1943) or species (T. klauberi:Bishop, 1943; Smith and Taylor, 1948).They are genetically distinct (Tan, 1993;Tan and Wake, 1995; Kuchta, 2002) anddistinguishable based on morphometric(Riemer, 1958) and osteological (Herre,1939; Tan, 1993) grounds. However, theinitial description was based on patho-logical animals, and T. klauberi was syn-onymized with T. torosa (Myers, 1942b;Twitty, 1942; Stebbins, 1951; Brattstromand Warren, 1953; see “Parasites” below).Specimens have been reported from north-western Baja California (Slevin, 1928;Smith and Taylor, 1948), but these recordsrequire verification.

Sierra newts occur at elevations belowabout 2,000 m and range along the west-ern slopes of the Sierra Nevada from ShastaCounty (Gorman, 1951) south to KernCounty (Stebbins, 1985). Many sources re-port a gap in the distribution betweensouthern Shasta and northern Butte coun-ties, but this may not exist, as Tan (1993)collected specimens in this area (also D.B.Wake, personal communication). Somesources consider Sierra newts to be deserv-ing of specific status (Twitty, 1942; Collins,1991; Tan, 1993; Kuchta, 2002), but othersdisagree (Stebbins, 1951; Riemer, 1958;Frost et al., 1992; Montanucci, 1992; VanDevender et al., 1992).

Tan and Wake (1995) outlined the his-torical biogeography of California newts.Based primarily on mitochondrial DNAevidence, they propose that Coast Rangenewts and Sierra newts differentiatedabout 8 million yr ago (mya), when Sierranewts existed in the uplifting centralSierra Nevada, and Coast Range newts in-habited the present day San Diego area.Roughly 5 mya, Coast Range newts ex-panded their distribution north to Mon-terey, while Sierra newts spread north andsouth in the Sierra Nevada. Coastal popu-lations of Coast Range newts invaded thesouthern Sierra Nevada and differenti-ated morphologically roughly 2 mya; Tan(1993) and Kuchta (2002) suggest thesepopulations are sufficiently divergent towarrant species status. Only relatively re-cently, after the central California inlandsea subsided, did Coast Range newts ex-pand north of Monterey to their currentdistribution. Early workers have sug-gested, based on differences in larval pig-mentation (Twitty, 1942) and preliminarygenetic data (Coates, 1967; Hedgecockand Ayala, 1974; Hedgecock, 1976), thatCoast Range newts are further divisibleinto northern and southern “races” lo-cated on either side of the Salinas Valley inMonterey County. While a genetic breakexists, it is not large relative to other ge-netic disjunctions in the species (Tan,1993; Kuchta, 2002).

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2. Historical versus Current Abundance.Historically, California newts were abun-dant throughout much of their range, ex-cept in the Santa Ynez Mountains of SantaBarbara County, where populations mayhave always been small (S. Sweet, personalcommunication, reported in Jennings andHayes, 1994a). In southern California,suitable habitat is patchy ( Jennings andHayes, 1994a); however, at appropriatesites California newts were historically“common” on the Pacific slope (Klauber,1928, 1930; Bogert, 1930; Pequegnat, 1945;Dixon, 1967; Brattstrom, 1988).

3. Life History Features.Some of the best documentation of Cali-fornia newt life history features is by Ritter(1897) and Storer (1925), both of whomworked in the northern part of the range.Unfortunately, both California newts andrough-skinned newts (T. granulosa) occurthere, and rough-skinned newts were notrecognized as a distinct species until thework of Twitty (1935). However, Califor-nia newts are the more abundant speciesin this area, and below I cite these authorswhere I feel the information applies toCalifornia newts.

A. Breeding. Reproduction is aquatic.i. Breeding migrations. Coast Range

newts migrate to ponds from December–early May, depending on locality, weatherconditions, and breeding habitat. Millerand Robbins (1954) state that the migra-tion of Coast Range newts to breedingponds requires 6–8 wk, but this has not

been rigorously studied. Mating at anyone site lasts from 3–12 wk (Miller andRobbins, 1954; De Lisle et al., 1986; Gam-radt et al., 1997), and in all situationsmales arrive before females and remainat the breeding site longer (Ritter, 1897;Smith, 1941; Stebbins, 1951; Miller andRobbins, 1954; Riemer, 1958). In thevicinity of Palo Alto and Berkeley, migra-tions of pond breeding populations occurfrom late December to early February(Storer, 1925; Twitty, 1942; Stebbins, 1951;Miller and Robbins, 1954; Riemer, 1958).However, in the same area, stream breed-ing populations migrate in March andApril after spring flooding subsides (Storer,1925; Twitty, 1942; Stebbins, 1951; Millerand Robbins, 1954; Riemer, 1958). South-ern Coast Range newts also migrate inMarch and April (Storer, 1925; Brame,1968; Kats et al., 1992), probably becausethey too breed most commonly in streams.Sierra newts migrate to breeding sites inJanuary and February, and breed fromMarch to early May (Stebbins, 1951; Riemer,1958).

Brown (S.C.) and P.S. Brown (1980) in-vestigated water balance in Californianewts and suggest that they possess somefeatures analogous to terrestrial anurans,such as toads in the family Bufonidae.They discovered that the urinary bladdercould store fluids in excess of 50% of thetotal body weight, and that water could beresorbed from the bladder. They alsofound that water is pulled from the ven-tral to the dorsal surface of the body,

probably via capillary action acting on thewarty skin of terrestrial individuals (seealso Lillywhite and Licht, 1974).

ii. Breeding habitat. Coast Range newtsbreed in ponds, reservoirs, and streams(Storer, 1925; Twitty, 1942; Riemer, 1958).Gamradt and Kats (1997) document thatstream-breeding newts in southern Cali-fornia commonly lay eggs in deep, slowpools, occasionally in runs, and almostnever in riffles. Egg masses are attached toaquatic vegetation, branches, and theouter surfaces of rocks (Ritter, 1897; Storer,1925; Twitty, 1942). In the central andnorthern portions of their range, CoastRange newt egg masses are not laid underrocks (Twitty, 1942); but in southern Cali-fornia, egg masses are commonly laidunder rocks in quiet stream pools (Gam-radt and Kats, 1996, 1997).

Sierra newts are more stream adaptedthan Coast Range newts. Relative toCoast Range newts, and analogous tothe stream-breeding red-bellied newts (T. rivularis), breeding Sierra newt malespossess a reduced tail fin, and females layeggs that are larger and commonly placedon the undersides of rocks in runningwater (Twitty, 1942). Sierra newts will,however, breed in ditches and otherbodies of water with little or no current(Twitty, 1942).

B. Eggs.i. Egg deposition sites. Storer (1925)

observed that eggs are most frequentlyfound from 7.5–10 cm deep, and whenwater levels rise to 30 cm or more the eggsdie. Mosher et al. (1964) reports findingeggs from a few centimeters to �1.5 mdeep.

ii. Clutch size. California newts layeggs in masses ranging from about 7–47eggs (Ritter, 1897; Storer, 1925; Twitty,1942; Brame, 1956, 1968; Mosher et al.,1964). Data are sparse, but it seems females lay from 3–6 masses each (Ritter,1897; Brame, 1968). Miller and Robbins(1954) report for a sample of newts fromcentral coastal California that the aver-age Coast Range newt ovary contains130–160 ova.

C. Larvae/Metamorphosis.i. Length of larval stage. The larval stage

lasts several months, with metamorphicanimals leaving the water in summer orfall, depending on conditions. Ritter(1897) observed that the average larvalperiod runs from March–October nearBerkeley, California. He estimated the av-erage size at metamorphosis to be 47 mmTL. Bishop (1943) noted that metamor-phosis for Coast Range newts begins inearly September and continues for somemonths; he estimates average size atmetamorphosis at 50 mm TL, with largeindividuals measuring 60 mm. Twitty(1935) estimates the size at metamor-phosis as approximately 45–55 mm TL.In 1998, at a vernal pool in SonomaCounty, I found the average size of 13

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metamorphic animals to be 43.8 � 2.0mm TL (24.6 � 1.2 mm SVL). The averageweight of 14 metamorphic animals was0.45 � 0.1 g. Metamorphosis began on 22July and ended on 3 August, after thepool dried completely. Metamorphosis inSierra newts does not seem to have beenmonitored. Bishop (1943) notes that lar-vae collected in late August range from55–62 mm TL.

Kaplan (1985) examined the effects ofegg size and food availability on larval de-velopment. Larvae from large eggs, whengiven an abundance of food, grew biggerand metamorphosed sooner than larvaefrom small eggs. Average time to meta-morphosis from the feeding stage rangedfrom about 75–92 d; size ranged from23.5–27 mm SVL. Conversely, under foodstress, larvae from large eggs, though stillmetamorphosing at a larger size, tookmuch longer to reach metamorphosisthan larvae from small eggs. Average timeto metamorphosis from the feeding stageranged from roughly 105–190 d; size atmetamorphosis was 21–23.75 mm SVL.This study suggests, among other things,that larger eggs may not be advantageouswhen food is limited and there is thethreat of habitat desiccation.

Riemer (1958) suggests that only rough-skinned newts are known to overwinter aslarvae, yet Storer (1925) collected fourCalifornia newt larvae in Bailey Canyon,Los Angeles County, in April and May1909, measuring 52–63 mm that werenearing completion of metamorphosis.Nevertheless, it seems that overwinteringby California newt larvae is uncommon.

ii. Larval Requirements.a. Food. California newt larvae eat small

invertebrates, but their diet has not beenrigorously studied. Ritter (1897) observedthat larvae will eat decomposing organicmatter, and perhaps conspecifics. Storer(1925) reports them feeding on mosquitolarvae in captivity.

b. Cover. Adult Coast Range newtsare cannibalistic (Ritter, 1897; Kats et al.,1992; Hanson et al., 1994; L. Kats, unpub-lished data, as cited in Elliot et al., 1993).Accordingly, Elliott et al. (1993) showedthat lab-reared Coast Range newt larvae(14–17 mm TL) from the Santa MonicaMountains use cover more when providedchemical cues from adult newts. In thesame study, chemical cues from odonatenaiads and belostomatids (Hemiptera)—both known predators of larvae—did notresult in substantially more cover use thancontrols, although the use of cover in-creased qualitatively.

In a second study, Kats et al. (1994)found that younger larvae use cover sig-nificantly more than older larvae. Thebehavior does not seem to be size depend-ent, and the authors suggest that the re-duced use of cover is a product of reducedpredation, as adult newts typically leave thestreams by July.

iii. Larval polymorphisms. Albino larvaehave occasionally been found (Riemer,1958; Wells, 1963; Dyrkacz, 1981).

iv. Features of metamorphosis. Similar tomany amphibians, California newt larvaeare induced to metamorphose by ponddrying (personal observations). At breed-ing sites with permanent water, the fac-tors influencing metamorphosis remainunstudied. The most detailed descriptionof metamorphosis is by Ritter (1897). Thefirst sign is the development of a duskycolor on the dorsum and a tinge of yellowon the venter. Subsequently, the colorsdeepen rapidly, the tail fin is absorbedfrom anterior to posterior, and the gills areabsorbed. When metamorphic animalsleave the water they possess adult col-oration (though the larval pigment pat-tern is visible underneath), the skin isgranular, and the gills are reduced to darkstubs. In the lab, this process requires over2 wk (Ritter, 1897). If newly metamor-phosed animals are kept in water, theywill drown (Ritter, 1897).

v. Post-metamorphic migrations. Californianewts leave the aquatic habitat after meta-morphosis, and do not return until theybreed. Dispersal into the terrestrial land-scape—where and how far they travel, theenvironmental clues employed in disper-sal, and the length of the juvenile stage—is in need of study. Trenham (1998)recaptured marked juveniles up to 3,500m from their natal ponds.

vi. Neoteny. Neoteny is unreported, butin permanent bodies of water Californianewt adults can remain aquatic year-round,and in this situation males retain theirsecondary sexual characters (Miller andRobbins, 1954). For example, on land adja-cent to the University of California’s Hast-ings Natural History Reserve, in MontereyCounty, a pond was deepened such that inthe summers it no longer dried; the follow-ing summer a large population of adultstook up permanent residence in the pond(P. Trenham, personal communication).

D. Juvenile Habitat. Unstudied.E. Adult Habitat. The terrestrial ecol-

ogy of California newts is incompletelystudied, hampering conservation efforts( Jennings and Hayes, 1994a). In centralCalifornia, Coast Range newts are foundin mountainous or rolling woodland andgrassland (Riemer, 1958; personal obser-vations). In southern California, CoastRange newts inhabit a drier zone of chap-arral, oak woodland, or grassland (Riemer,1958). Sierra newts are found in mixedSierran Forest.

F. Home Range Size. Unknown.G. Territories. Unknown.H. Aestivation/Avoiding Desiccation.

California newts leave the aquatic habitatwithin a few weeks of breeding, and aesti-vate terrestrially during the dry summer.Mesic microclimates, such as deep leaf lit-ter and animal burrows, are used as aesti-vation sites, and some individuals migrate

considerable distances to them (see “Sea-sonal Migrations” below; Trenham, 1998).Not all aestivation sites are distant fromwater, however, as Stebbins (1951) reportsunearthing 14 aestivating adults 1.5 mfrom a stream in Los Angeles County. Theaestivation site was under a boulder, in ahole partly filled with “slightly damp,coarse sand” (p. 25).

I. Seasonal Migrations. Following meta-morphosis, California newts emigrate fromthe breeding site and spend the next fewyears growing to sexual maturity (see“Age/Size at Reproductive Maturity” below).When sexually mature, they migrate to abreeding site during winter or spring rainsto mate (see “Breeding migrations” above).Following mating, they typically returnto the terrestrial environment. Miller andRobbins (1954) found that about half ofmales and females of breeding size had im-mature gonads. If California newt breed-ing resembles red-bellied newt breeding,males typically breed annually while females skip 1, 2, or more years betweenreproductive events (Twitty, 1966).

California newts can migrate large dis-tances between breeding and aestivationsites. For example, Trenham (1998) recap-tured adult newts up to 3,200 m from thebreeding pond where they were marked.However, when suitable aestivation sitesare nearer, migrations may not be so long(P. Trenham, personal communication;see “Aestivation/Avoiding Desiccation”above). California newts typically returnto the same breeding site repeatedly(but see Trenham, 1998). Endler (1970)demonstrated experimentally that Cali-fornia newts exhibit a kinesthetic, or bodyposition, sense in their homing behav-ior, and observed that migrating newtscorrect for movements around objectssuch that a straight course is maintained.Twitty (1966) established the importanceof olfaction in the navigation of red-bellied newts, and Landreth and Fergu-son (1967a,b) demonstrated the use ofcelestial cues in the navigation systemof rough-skinned newts. None of theseexperiments have been replicated on Cal-ifornia newts.

J. Torpor (Hibernation). Not known toexist.

K. Interspecific Associations/Exclusions.Aside from the recent work of L. Kats andcolleagues, little is known about the com-munity ecology of California newts (see“Conservation” below for a discussion ofintroduced predators). In southern Cali-fornia and the Sierra Nevada, Californianewts are the only stream-breeding sala-mander.

L. Age/Size at Reproductive Maturity.Riemer (1958) found the smallest sexuallymature animals to be around 50 mm, butthere is variation. Both Ritter (1897) andMcCurdy (1931) estimate the age of repro-ductive maturity to be reached after 3 yr;however, neither followed marked animals

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in the field. Work on experimentally re-leased rivularis-torosa and rivularis-sierraehybrids suggests that reproductive matu-rity requires 7–8 yr or longer (Twitty,1961b, 1966). Unfortunately, these recap-ture data were never clearly summarizedbefore Twitty’s untimely death, and it isunclear how relevant hybrid data are toCalifornia newt sexual maturity.

M. Longevity. The longevity of Cali-fornia newts is unknown, although theanimals are certainly long-lived. If red-bellied newts are any indication (Twitty,1966), many California newts live to be �20 yr old.

N. Feeding Behavior. Adult Californianewts feed terrestrially with a highly de-veloped tongue-projection system, in-cluding substantial anterior movement ofthe ceratohyal (Findeis and Bemis, 1990).Conversely, aquatic feeding by adults isgape-and-suck, and further specializationof the feeding apparatus is probably con-strained by trade-offs imposed by feedingboth terrestrially and aquatically (Findeisand Bemis, 1990).

There has been no systematic study ofthe diet of terrestrial California newts, butRitter (1897) reports that newts feed ontheir own sloughed-off skin, earthworms,insect adults and larvae, sowbugs, smallsnails and slugs, and other small inverte-brates. Adults in the aquatic environmenthave been observed to feed on coleopter-ans, lepidopterans, and plecopterans (Han-son et al., 1994), ephemeropterans and theoligochaete Eisenia rosea (Kerby and Kats,1998), and probably on the egg masses ofCalifornia red-legged frogs (Rana draytonii;Rathbun, 1998; newts not identified tospecies). Furthermore, several workershave documented predation by adults onconspecific egg masses, both during andafter oviposition (Ritter, 1897; Pequegnat,1945; Kaplan and Sherman, 1980; Mar-shall et at, 1990; Kats et al., 1992), and onconspecific larvae (Ritter, 1897; Kats et al.,1992; L. Kats, unpublished data, as citedin Elliott et al., 1993, and Kats et al., 1994;Hanson et al., 1994). Hanson et al. (1994)found a nestling bird (0.3 g), probablyAnna’s hummingbird (Calypte anna), inthe stomach of a small female newt insouthern California.

O. Predators. The egg masses, em-bryos, and adults of California newtspossess tetrodotoxin (TTX), a potent neu-rotoxin, and are thus generally unpalat-able (see “Anti-Predator Mechanisms”below). Only common garter snakes(Thamnophis sirtalis) have been systemati-cally shown to possess resistance to TTX(Brodie and Brodie, 1970). However, Cali-fornia newt larvae are not poisonous (see“Anti-Predator Mechanisms” below), andindividuals in this life history stage maybe an important food resource for new-born individuals of some garter snakes(Fitch, 1940, 1941; Fox, 1951), includingFederally Endangered San Francisco garter

snakes (T. s. infernalis; S. Barry, personalcommunication, as cited by Jennings andHayes, 1994a). I examined the stomachcontents of 23 live Pacific Coast aquaticgarter snakes (T. atratus) in Sonoma County,California, and found five with one ormore California newt larvae in their stom-ach. Fox (1951) reports finding Califor-nia newt adults in the stomach ofPacific Coast aquatic garter snakes. Jen-nings and Cook (1998) found that intro-duced American bullfrogs (Rana catesbeiana)in Sonoma and Riverside counties notonly eat larval California newts, but sur-prisingly also adults. Kats et al. (1998), inLos Angeles County, discovered a ring-necked snake (Diadophis punctatus) eatingan adult newt, but the snake was lethargic,and in the lab regurgitated the deadnewt. Also in southern California, twointroduced predators, crayfish and mos-quitofish, are causing serious declines (see“Conservation” below) via predation onegg masses and larvae. For a discussion ofcannibalism of egg masses, see “FeedingBehavior” above.

P. Anti-Predator Mechanisms. Adults andP. Anti-Predator Mechanisms. Adults andembryos of California newts containthe potent neurotoxin TTX (Twitty andJohnson, 1934; Twitty, 1937; Wakely et al.,1966; Brodie et al., 1974b). This is the sametoxin as found in the ovaries of pufferfish (family Tetraodontidae; Buchwald et al., 1964), as well as in a variety of other taxa, including other amphibians (Daly etal., 1987), echinoderms (Maruyama et al.,1984), cephalopods (Sheumack et al., 1978),and bacteria (Noguchi et al., 1986; Thue-sen and Kogure, 1989). It is possible thatthis neurotoxin is produced by symbioticgut bacteria (Mosher and Fuhrman, 1984;Noguchi et al., 1986, 1987; Thuesen andKogure, 1989), but the situation is com-plex and it is not clear how newts acquireTTX (Mosher and Fuhrman, 1984; Daly etal., 1987). TTX is found in the skin, ovariesand ova, muscle, and blood of adult newts;the liver, viscera, and testes contain onlyminute amounts (Wakely et al., 1966). Em-bryos possess TTX throughout their body,but larvae lose their toxicity shortly afterthe yolk is absorbed (Twitty and Johnson,1934; Twitty, 1937), suggesting that em-bryos obtain their poison maternally.

Rough-skinned newts are the mosttoxic salamanders in the world, and Cali-fornia newts are reported to be about1/10 as toxic (Brodie et al., 1974b). To putthis in perspective, Brodie et al. (1974b)estimated that the skin of adult rough-skinned newts from Benton County, Ore-gon, could potentially kill 25,000 20-gmice, whereas the skin of adult Californianewts could kill 1,200–2,500 20-g mice.More recent work has uncovered substan-tial geographic variation in the toxicity ofrough-skinned newts (Hanifin et al., 1999).Variation in California newt toxicity is inneed of examination.

California newts have a cryptic browndorsum and an aposematic yellow-to-orange venter. When harassed, Californianewts assume a defensive posture calledthe unken reflex, which exposes the ventralaposematic coloration: the belly is presseddown against the substrate, the throatraised up with eyes closed and depressed,the limbs stiffly extended outward, andthe tail raised straight over the body (Steb-bins, 1951; Riemer, 1958; Johnson andBrodie, 1972, 1975; Brodie, 1977; rough-skinned newts curl their tail tip; Riemer,1958). Toxicity, aposematic coloration, anddefensive posturing form a co-adaptiveunit ( Johnson and Brodie, 1972, 1975;Brodie, 1977). Naylor (1978) has suggestedthat the frontosquamosal arch of newts isan anti-predator adaptation designed toadd structural support to the skull and pro-tect retracted eyes. California newts pro-duce a repertoire of sounds (Davis andBrattstrom, 1975), and Brodie (1978) sug-gests that predators may associate somesounds with toxic skin secretions.

Q. Diseases. Unknown. Some animalsin San Diego County exhibit extreme warti-ness now recognized as pathological (see“Historical versus Current Distribution,”above and “Parasites,” below).

R. Parasites. Ingles (1936), Lehmann(1954), and Goldberg et al. (1998c) doc-umented the presence of parasites inCalifornia newts. Goldberg et al. (1998c)found that in 68 Coast Range newts fromOrange and Los Angeles counties, 52 wereinfected with at least one nematode. Fournematode species were discovered (aver-age number of nematode species/infectednewt � 1.3 � 0.5), and they concludedthat the parasite infracommunities of Cal-ifornia newts are depauperate relative toother vertebrates. There are no data on theeffect of parasite loads on the fitness orecology of California newts. Some ani-mals in San Diego County exhibiting ex-treme wartiness were once recognized as adistinct taxon, but it was later determinedthat the warty phenotype was pathologi-cal (see “Historical versus Current Distrib-ution” above).

4. Conservation.California newt populations are impactedby breeding site degradation ( Jenningsand Hayes, 1994a), destruction of sum-mer aestivation sites and migration routes( Jennings and Hayes, 1994a; see alsoSemlitsch, 1998), road kills (Storer, 1925;R.C. Stebbins, personal communication; P.Trenham, personal communication), large-scale commercial exploitation ( Jenningsand Hayes, 1994a), altered sedimentationdynamics in stream pools resulting fromwildfires (Gamradt and Kats, 1997; Kerbyand Kats, 1998), and riparian habitat degra-dation (Faber et al., 1989; Jennings andHayes, 1994a).

Furthermore, in the Santa MonicaMountains of Los Angeles County, two

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introduced predators, crayfish (Procam-barus clarkii) and mosquitofish (Gambusiaaffinis), have caused serious declines andexterminated some populations (Gamradtand Kats, 1996; Gamradt et al., 1997).Crayfish are sold as bait, and mosquitofishare distributed broadly for mosquito con-trol, so both are widespread (Gamradtand Kats, 1996). Also in the Santa MonicaMountains, Anzalone et al. (1998) showedthat solar UV-B causes high rates of em-bryonic mortality in California newt eggmasses (see also Blaustein et al., 1998).The genetically distinct San Diego Countypopulations in the Cuyamaca Mountains(see “Historical versus Current Distribu-tion” above) are currently restricted to theBoulder, Ceder, and Conejos Creek sys-tems, where populations persist in small,isolated pockets (from about 15–20 breed-ing adults; E. Ervin, USGS, personal com-munication). Exotic predators such ascrayfish, green sunfish (Lepomis cyanellus),and rainbow trout (Oncorhynchus mykiss)occur in the perennial reaches of streamsoriginating in the Cuyamaca Mountainsof San Diego County. Because these preda-tors and California newts do not co-occur,they may be excluding newts (E. Ervin,USGS, personal communication). Finally,Fisher and Shaffer (1996) document a de-cline of California newts in the centralvalley of California, where these animalsare peripherally present.

California newt populations south ofthe Salinas River in Monterey Countyare considered by the California Depart-ment of Fish and Game to be Species ofSpecial Concern ( Jennings and Hayes,1994a). While this designation carriesno legal weight, it is a helpful manage-ment tool highlighting concerns aboutthe species’ status. Moreover, a large por-tion of verified populations in San DiegoCounty are extinct ( Jennings and Hayes,1994a), and because of the distinctive-ness of the animals in this area (see“Historical versus Current Distribution”above) the status of these populationswarrants further investigation.

Family SirenidaePseudobranchus axanthus Netting and Goin, 1942(b)SOUTH E R N DWAR F SI R E N

Paul E. Moler

1. Historical versus Current Distribution.Southern dwarf sirens (Pseudobranchus ax-anthus) are restricted to peninsular Florida;their northern boundary includes Alachua,Clay, Duval, Levy, and Putnam counties.Two subspecies, narrow-striped dwarf sirens(P. a. axanthus) and Everglades dwarf sirens(P. a. belli), are recognized (Moler andKezer, 1993; Crother et al., 2000). Thecurrent distribution of southern dwarfsirens is undoubtedly reduced compared

with their historical distribution, as wet-lands in peninsular Florida have been re-duced through drainage of surface watersassociated with residential, agricultural,and silvicultural development.

D. Juvenile Habitat. Same as adulthabitat.

E. Adult Habitat. Southern dwarf sirensare most abundant in heavily vegetatedmarshes and shallow lakes (Carr, 1940a).

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2. Historical versus Current Abundance.Southern dwarf sirens are often commonin suitable habitat. Current numbers arereduced relative to historical abundancedue to the loss of wetland habitat.

3. Life History Features.A. Breeding. Reproduction is aquatic.i. Breeding migrations. Southern dwarf

sirens do not migrate. They breed andpermanently reside in the same aquatichabitats.

ii. Breeding habitat. Southern dwarf sirenslive and breed in heavily vegetated marshesand shallow lakes.

B. Eggs.i. Egg deposition sites. Eggs are laid singly

or in small bunches among aquatic vege-tation throughout the spring (Carr, 1940a;Netting and Goin, 1942b). According to Pe-tranka (1998) the oviposition period lastsfrom early November to March. Newly laideggs average 3 mm and are surrounded bythe vitelline membrane and three jelly en-velopes (Noble and Richards, 1932; seealso Petranka, 1998).

ii. Clutch size. Unknown.C. Larvae. Newly hatched larvae are

between 10–11.5 mm SVL, colored browndorsally with lighter stripes on the dorsalmidline and lateral portions of the bodyand head (Goin, 1947c; see also Petranka,1998). They have limb buds (Noble, 1927b).Ashton and Ashton (1988) indicate Pseudo-branchus larvae make take 2 yr to reachsexual maturity.

They may be abundant in floating matsof vegetation or in mucky shoreline de-posits.

F. Home Range Size. Unknown.G. Territories. Unknown.H. Aestivation/Avoiding Desiccation.

Southern dwarf sirens burrow into bottomsediments and form a protective cocoonwhen wetlands dry. Individuals may re-main buried for several months until theirwetland refills (Freeman, 1958; Etheridge,1990a).

I. Seasonal Migrations. None.J. Torpor (Hibernation). Carr (1940a) re-

ported that southern dwarf sirens “havebeen found hibernating in deep mud.”Nevertheless, although they may becomeinactive during prolonged periods of coldweather, they may be collected throughoutthe winter, especially in southern Florida.

K. Interspecific Associations/Exclusions.Southern dwarf sirens occur sympatrically,but only occasionally syntopically, withnorthern dwarf sirens (P. striatus) in north-ern peninsular Florida. In areas of sympa-try, northern dwarf sirens are typicallyfound in more acidic habitats than aresouthern dwarf sirens, but they are knownto occur syntopically at a few sites (Molerand Kezer, 1993).

L. Age/Size at Reproductive Maturity.Unknown.

M. Longevity. Unknown.N. Feeding Behavior. Reported foods

include amphipods, chironomid lar-vae, aquatic oligochaetes, and ostracods

Southern Dwarf Siren (Pseudobranchus axanthus)

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