Pacific Science (1979), vol. 33, no. 2© 1980 by The University Press of Hawaii. All rights reserved

The Rainbow Skink, Lampropholis delicata, in Hawaii 1

JAMES K. BAKER 2

ABSTRACT: The rainbow skink, Lampropholis delicata, arrived in Hawaiias an accidental import from Australia sometime about 1900, but its trueidentity went unknown until recently. Previously, L. delicata in Hawaii hadbeen identified as Lipinia noctua, Leiolopisma hawaiiensis, and Lygosomametallicum (the latter apparently does not occur in Hawaii). Lampropholisdelicata establishes high-altitude records for reptiles in Hawaii at 1130 and1220 m elevation on the islands of Hawaii and Kauai, respectively. Variationsin body size and numbers of eggs produced in populations on Hawaii, Kauai,and Oahu suggest that competition for space and food may be lowering re­productive capacity, and inhibiting growth in the relatively dense populationson Oahu.

TAXONOMY AND DISTRIBUTION

THE RAINBOW, penny, or garden skink, Lam­propholis (Leiolopisma) delicata De Vis 1888,arrived in Hawaii from Australia as an acci­dental import sometime about 1900 (Oliverand Shaw 1953, as reported for Lygosomametallicum) , but its true identity went un­known until recently. The earliest knowncollection of Lampropholis delicata in Hawaiiis a previously unreported specimen in thecollections of the Bernice P. Bishop Museum,Honolulu (BBM 899 = old BBM 219), taken onthe island of Oahu in Moanalua Valley in1909 by J. F. G. Stokes. The specimen wasidentified at that time as a moth skink, Lipinia(Leiolopisma) noctua Lesson 1830, apparentlybecause of the general similarity of the speci­men with the moth skink already known inHawaii. But it was later reclassified as a metal­lic skink, Lygosoma metallicum (O'Shaugh­nessy) 1874, following the taxonomic worksof Brongersma (1942) and Oliver and Shaw(1953).

The second'known Hawaiian specimen wascollected by W. C. van Heurn in Honolulu in1919, and was deposited in the Rijkmuseumvan Natuurlijke Histoire, Leiden, The

I Manuscript accepted 16 November 1978.2 Hawaii Field Research Center, Hawaii Volcanoes

National Park, Hawaii 96718.

Netherlands (CAT. NO. 4866). It was classifiedas Lygosoma metallicum and reported on assuch by Brongersma (1942), who was un­aware of the paper written 4 years earlier byLoveridge (1939). Loveridge had examined asmall series of Lampropholis delicata fromOahu in the collections of the Museum ofComparative Zoology, Harvard University(CAT. NOS. 44,234-44,237), and had con­cluded that they represented a new speciesendemic to the Hawaiian Islands. He namedthe skink Leiolopisma hawaiiensis, distin­guishing it from the moth skink.

When Oliver and Shaw (1953) beganworking up the collections they had made in1944, they were not yet aware of Bron­gersma's 1942 paper calling the species inHawaii Lygosoma metallicum. Independentof Brongersma, they arrived at the same con­clusion that he had, after which Loveridgereexamined his type material and concurredthat Leiolopisma hawaiiensis was, indeed,synonymous with Lygosoma metallicum.Other researchers since (Baker 1976, Brown1953, Couzyn 1973, Hunsaker and Breese1967) followed this lead and also used thename Lygosoma metallicum, for what is inreality Lampropholis delicata. As far as I amaware, Lygosoma metallicum does not occurin Hawaii, but three additional skink speciesare present: the moth skink; the snake-eyedskink, Cryptoblepharus (Ablepharus) boutonipoecilopleurus (Wiegmann) 1835; and the

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azure-tailed skink, Emoia cyanura (Lesson)1830.

In 1972, a skink that had been captured bya pet housecat in the community of Volcanoon the island of Hawaii at 1130 m (3700 ft)elevation was given to me for identification.This specimen was of interest because reptileshad not previously been known to occur inthis area, or at that altitude anywhere in theHawaiian Islands. In using the existing litera­ture on Hawaiian reptiles, the skink keyedout to Lygosoma metallicwn, which is com­mon on Oahu but until this time unknownelsewhere in Hawaii. Additional specimenswere collected for study from Volcano in1972, 1976, and 1977 (BBM 5822-5840).

In 1976, while examining the collections ofthe Bernice P. Bishop Museum, I found anadditional unreported collection of theseskinks taken by K. J. Frogner in 1963 fromthe head of Kalalau Valley at 1220 m (4000 ft)elevation on the island of Kauai (BBM 2729­2734). Subsequently, in 1977, I collectedothers from Kalalau Valley, as well as fromthe adjacent Waimea Canyon from 1120 m(3675 ft) down to 304 m (1000 ft) elevation(uncatalogued specimens in The AustralianMuseum, Sydney).

A letter was sent to Harold Cogger,Curator of Amphibians and Reptiles at TheAustralian Museum, requesting informationon Lygosoma metallicum in that country.Cogger's response brought up the question ofthe true identity of the Hawaiian forms. Hewrote (in 1976):

The identity of the introduced Hawaiian skink, whoseorigin has long been attributed to Australia, aroused myinterest several years ago. On a visit to the U.S. I saw acopy of the (then) newly released field guide of Cochranand Goin, in which they illustrate a specimen of Leiolo­pismo metallicum. As the specimen in the photograph wasclearly not L. merallicum, I subsequently borrowed acouple of preserved Hawaiian specimens from Dr.Sherwood Minton.

As expected, these were not L. metallicum but a beastclosely allied to Leiolopismo delicolo, a common easternAustralian species which has subsequently been shownto encompass a species-complex with several undescribedforms. As the Hawaiian specimens were not from anypopulation with which I am familiar, I sent the specimenson to Mr. Peter Rawlinson at La Trobe University, whois an authority on this group of skinks. We subsequentlyconfirmed that the specimens from Hawaii were a formof L. delicolo, and that's where the matter rested.

PACIFIC SCIENCE, Volume 33, April 1979

While Cogger and Rawlinson did notpursue the matter further, each had deter­mined the identity of this particular skink asLeiolopisma delicata. Since that time, how­ever, Greer (1974) has placed Leiolopismadelicata in the genus Lampropholis (all thetaxonomy used herein follows Greer), a genuscommon to eastern and southeastern Aus­tralia, including northern Tasmania.

The matter of the identity of the Hawaiianskink was personally taken up with Greer,who is also a Curator of Amphibians andReptiles at The Australian Museum. Hereexamined the type material of Leiolopismahawaiiensis at Harvard, and studied collec­tions of skinks I sent from the islands ofHawaii, Oahu, and Kauai (uncataloguedspecimens in The Australian Museum, Syd­ney). Greer replied that "there is nothing inthe type series of L. hawaiiensis that wouldexclude this name from the synonymy ofLampropholis delicata," and that "the biolog­ical identity of the Hawaiian animals isclear enough ... in my opinion they representthe southeastern Queensland population ofwhat is known here as Lampropholis de­licata. "

The foregoing should now clarify the con­fused taxonomy of the rainbow skink inHawaii and establish Lampropholis delicataas the proper name for this Australian import.Of the vernacular names "rainbow skink,""penny skink," or "garden skink" used inAustralia (Greer, personal communication1977), the common name "rainbow skink"would seem appropriate in Hawaii becauseof the colorful irridescent hues of the scalesand the rainforest distribution of manyHawaiian L. delicata.

Lampropholis delicata is of importance inHawaiian zoogeography because the speciesestablishes known high-altitude records forHawaiian reptiles at 1130 mon Hawaii and1220 m on Kauai. [A skink was observed butnot captured at 1760 m (5800 ft) on the extinctvolcano Mauna Kea on the island of Hawaiiby Frederick R. Warshauer in 1977. A verbaldescription of the skink indicates that it wasprobably L. delicafa.] All other reptiles inHawaii are lowland forms usually rangingonly to about 600 m (2000 ft) elevation (Hun­saker and Breese 1967, Oliver and Shaw

The Rainbow Skink in Hawaii-BAKER

1953), with specimens of the snake-eyedskink having been taken at 975 m (3200 ft) inthe Kau Desert area of the southeastern partof the island of Hawaii (Fisher 1948).

The fact that Lampropholis delicata occursand thrives at significantly higher (and wet­ter) elevations in Hawaii than do other locallizard species is of interest in view of Greer's(personal communication 1977) commentsthat L. delicata in Australia is a "partlymountainous species generally found in wet,to dry sclerophyll forest." This would tend toexplain the dry lowland through wet uplanddistribution of the rainbow skink in Hawaii.

It is believed that Lampropholis delicatafirst arrived in Hawaii on Oahu by accidentaltransport in shipments of lumber or plantmaterials (Oliver and Shaw 1953, as reportedfor Leiolopisma metallicum). It is not sur­prising, then, that these lizards could eventu­ally reach other islands in Hawaii, and theywould be expected to. In the case of the islandof Hawaii population, it is suspected thatresidents commuting between Honolulu,Oahu, and seasonal homes in Volcano in­advertently transported the rainbow skink inpotted plant materials and/or cargoes ofhousehold items. One Volcano resident re­ported finding a skink inside the familyautomobile. For similar reasons, the rainbowskink will eventually spread to other parts ofthe island, and to other islands and locationsin Hawaii, if it has not already done so.

The Volcano population may be less than10 years old, as none of these skinks had beenreported before 1972 by any of the localresidents. The Kauai skinks were first col­lected in 1963. Both populations, therefore,are very likely more recent than the Oahuintroduction.

While population densities have not beendetermined for any of the populations, it wasstated by Oliver and Shaw (1953) that therainbow skink is abundant on Oahu, and thatits rapid multiplication on that island hadproduced "remarkable" numbers of skinks.In this I can concur. Oliver and Shaw (1953)reported 44 skinks beneath a single banyantree, and I saw an estimated 300-400 in asmall area of about 100 m2 beneath threelarge mango trees in Nuuanu Park, Honolulu,where they were apparently feeding on insects

209

attracted to the many rotting mango fruits.I captured 91 skinks in a few hours, and theywere so abundant that several at one timecould be seen scurrying through the grass andleaves. I found several eggs under leaves anddebris.

Observations in Volcano indicate that therainbow skink is only sparsely distributedaround a small area of scattered residencescovering approximately 100 ha (about 240acres). There it is commensal with humansaround lawns and gardens, and along road~

sides, where the skinks venture out into opensunlight in clearings, on rock and wood piles,and around buildings. More and more resi­dents are finding them, and some report themmore common now (1978) than when firstobserved in 1972.

In comparison to its relative scarcity inVolcano, the rainbow skink is much moreabundant on Kauai, where it is commonalong trails, roadsides, and in relatively openareas of fcrests, but nowhere did I find it onKauai quite as abundant as I observed it insome areas on Oahu. Numbers on Kauaiseem to diminish in the denser, heavily shadedareas of forest, and it appears that theseshinks are probably dispersing through for­ests by moving primarily along roadsides andtrails.

It is suspected that the Hawaii Islandpopulation will disperse similarly, and it isprobable that the rainbow skink will even­tually become widespread and common overlarge areas of the island, including the HawaiiVolcanoes National Park, adjacent to Vol­cano, where nonnative animals are undesir­able in any large numbers.

BODY SIZE AND EGG PRODUCTION

Among the three populations of Lam­propholis delicata on Hawaii, Kauai, andOahu, variations occur in mean body (snout­vent) length and in the numbers of eggsproduced. Sexually mature females on Kauaiand Hawaii are larger than females on Oahu(see Table I). Measurements I took of adultfemales from Oahu averaged 38.6 mm in bodylength (maximum of 42 mm), while thosefrom Hawaii and Kauai averaged 41.2 mm

210 PACIFIC SCIENCE, Volume 33, April 1979

TABLE 1

A VERAGE BODY (SNOUT-VENT) LENGTH AND CLUTCH SIZE (± I STANDARD DEVIATION) OF 64 FEMALE

Lampropholis delicata FROM THREE ISLAND POPULATIONS IN HAWALL

POPULATION AVERAGE BODY AVERAGE CLUTCH

LOCATION N LENGTH (mm) CLUTCH SIZE RANGE

Oahu 45 38.6 ± 1.7 3.5 ± 1.8 1-5Kauai 9 41.8 ± 3.5 4.1 ± 1.0 3-6Hawaii 10 41.2 ± 2.8 4.7 ± 1.3 3-7

NOTE: See text for statistical significance between means.

and 41.8 mm, respectively (maximum lengthof 46 mm oIl both islands). These averagesare 2.6 mm and 3.2 mm more than that ofOahu females. Fifteen females from Oahumeasured by Oliver and Shaw (1953) averaged39.8 mm (maximum of 44 mm), 2 mm lessthan the average of the present Kauai femalesample.

Statistical t-tests showed there was a sig­nificant difference between the mean bodylengths of Hawaii Island and Oahu females(£53 = 3.85, P < 0.01); and between Kauaiand Oahu females (t52 = -4.31, P < 0.01);but not between Hawaii Island and Kauaifemales (t 17 = -.48, P > 0.01).

The apparent selection for small body sizeof Oahu fenulles is due most likely to the highpopulation densities, causing competitionamong individuals for available space andfood. Competition with other species, as withthe snake-eyed and moth skinks may alsoplay a role. Such inter- and intraspecificcompetition, reducing body size, would alsocause reduced egg production, and it happensthat the mean number ofeggs per female fromOahu is lower than the mean numbers of eggson Kauai and Hawaii (see Table I).

The average number of eggs reported byOliver and Shaw (1953) for 15 Oahu femaleswas 2.9, and none carried more than 4 eggs.Sevetal had only I egg, but Oliver and Shawqualify these figures by stating that theirskinks had previously been opened forpreservation purposes, and it was possiblethat some of the eggs could have been lostprior to counting. All eggs counted in thelresent study were obtained from females

newly captured, or from preserved specimensat had not been previously opened.In a series of 45 freshly opened females

from Oahu that I had taken in 1977, theaverage number ofeggs was 3.5, ranging fromI to 5 (see Table I). Numbers of eggs for10 Hawaii Island females averaged 4.7,ranging from 3 to 7. Numbers of eggs for 9Kauai females averaged 4.1, ranging from3 to 6. None of the Hawaii Island or Kauaifemales had fewer than 3 eggs each, though anumber of the Oahu females had only I or 2eggs each. The Hawaii Island populationaveraged 1.2 (34 percent) more eggs perfemale, and the Kauai population averaged0.6 (17 percent) more eggs per female, thanOahu females.

Statistical t-tests showed there was sig­nificance in the mean numbers of eggsbetween Hawaii and Oahu females (£53 =2.81, P < 0.01), but not in the mean numbersof eggs between Kauai and Oahu females(£52 = 1.41, P > 0.01).

In an oviparous species, the number ofeggs produced varies to some extent withindividual body size. Larger individuals withmore internal body capacity lay more eggsthan do smaller individuals of the samespecies. This phenomenon is summarized byLack (1954, pp. 45-52), whose summary alsoshows that egg production increases with theage of females if the older females are larger.It was observed that larger females of therainbow skink did, indeed, tend to carrymore eggs (see Figure I). An analysis of theregression slope showed that body size versusclutch size was significant at the 0.025 percentlevel (F, 4 = 12.2, P < 0.025), and it ap­proached' significance at the 0.01 percentlevel.

In the case of the Hawaii Island females, Ifound that as numbers of eggs increased from3 to 7, the average body length increased

The Rainbow Skink in Hawaii-BAKER

46

ill45

44

E 43 ;;.5 42If-

" 41z/~

40f-Z

/'"' 39>I

f-38" /'0z N,,14

Ul 37

/' N-2136

35

34N'6 N"16

4 6

NUMBERS OF EGGS

FIGURE 1. Combined snout-vent lengths versusclutch sizes of 60 female Lamprophofis defieata frompopulations on Hawaii, Kauai, and Oahu. Otherspecimens containing as few as I, or as many as 7eggs, were not included in the data because of smallsample size. Horizontal lines represent means; ver­tical lines represent ranges of snout-vent lengths;boxes on either side of the mean represent I standarddeviation; N = sample size. The regression line equationis Y = 34.5487 + 1.27619(X). The mean of the Yaxisis 39.48 mm; the mean of the X axis is 3.78 eggs.

about 1.5 mm for each additional egg. Bycomparing egg volume with body length itwas calculated that an increase in bodylength of at least 1.2 mm would be required toaccommodate each additional egg. Thismeasurement falls within the actual 1.5 mmincrease measured.

In animals, a correlation between repro­ductive capacity and food availability is alsogenerally accepted (Lack 1954, pp. 45-52).An animal that eats only enough food tomaintain itself without reproducing caneither reproduce and starve, or it can ceasereproducing and survive. If, however, food isin excess of nonreproductive nutritionalneeds, and other factors are not limitingreproduction, then the reproductive capacityof individuals can be expected to reach itsmaximum potential. All of the rainbow skinkstaken on Hawaii and Kauai in this study werecollected near midday, and stomachs ap­peared full, indicating each was able tocapture whatever food was wanted within

211

the first half-day of foraging. It appears,therefore, that sufficient food is available tothese populations for optimum growth andreproductive effort. Stomach contentsob­served in the Oahu skinks, which werecollected in midafternoon, seemed less en­gorged, but no precise, comparative measure­ments were made of any of the lizards forvolumes of food consumed.

An analysis of the kinds of food eaten wasmade on a collection of rainbow skinks fromVolcano. The foods were principally variousColeoptera, Corrodentia, Diptera, Embiop­tera, Homoptera, Hymenoptera, and Lepi­doptera. Besides these insects, invertebratessuch as annelids, arachnids, and symphillids,were also taken.

The probable limited food and space inthe dense Oahu populations, and competitionwith other species, may well be the limitingfactors to body growth and reproduction. Itseems significant to me that none of the Oahuskinks had the maximum of 6 to 7 eggs asobserved in the Kauai and Hawaii popula­tions, although 24 (53 percent) of my 45 Oahufemales, as well as a number of those 15 Oahufemales observed by Oliver and Shaw (1953),did have body sizes large enough to carry 6or 7 eggs. The relatively low maximum eggnumber in Oahu Lampropholis delicata (5eggs) seems to indicate that limiting factorsare in force which are inhibiting femalegrowth and reproductive potential on thisisland.

No comparative data are available on bodylengths and egg production of Lampropholisdelicata in Australia (Greer and Cogger,personal communications), but it could prob­ably be shown that the populations on Hawaiiand Kauai show significantly higher measure­ments in both parameters than do theAustralian populations.

In summary, the present investigationregarding the arrival, establishment, inter­island spread, and selected ecological aspectsof Lampropholis delicata in Hawaii adds toexisting knowledge of how certain alienspecies can become established in new is"land habitats and niches, and can flourishin the absence of coevolved ecological re­straints.

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ADDENDUM

Subsequent to completion of this manu­script, the following new data were obtainedon the distribution of the rainbow skink inHawaii from Sean McKeown (personal com­munication 1978). All observations and col­lections were made since September 1975.Oahu-common many localities; Kauai­common many localities; Hawaii-collectedfrom Hilo and Volcano; Molokai-collectedin the vicinity of Hotel Molokai; Maui­common around Kahului and Hana; Lanai­common in many localities including LanaiCity at 457 m (1500 ft)and high fern forestlocations at 838 m (2750 ft). These data addthree new islands (Molokai, Maui, and Lanai)to the statewide distribution of Lampropholisdelicata, which rounds out its range in Hawaiito all the major inhabited islands. McKeownalso suggests that the widespread abundanceof the rainbow skink in Hawaii is a cause forthe present rarityofmoth skinks, and possiblythe azure~tailed skink. The belief that therapid expansion of rainbow skinks in Hawaiiwas replacing moth skinks was also suggestedby Hunsaker and Breese (1967, as reportedfor Lygosoma inetallicum).

ACKNOWLEDGMENTS

I wish to thank Mrs. LaVieve Forbes ofVolcano for showing me the first skink(reptile) collected from that community, andVolcano residents William P. Mull, Terry T.Parman, Clifton J. Davis, and Frederick R.Warshauer for information on the occurrenceof rainbow skinks around private homes. Ialso wish to thank Len Anderson of the U.S.Geological Survey, Hawaiian Volcano Obser­vatory, for mathematical computations ofegg and body volumes ; Harold Cogger andAllen Greer, Jr., of The Australian Museumfor assistance in determining the propernomenclature of Lampropholis delicata; Clif­ton J. Davis of Volcano and the Bernice P.Bishop Museum for determining invertebrate

PACIFIC SCIENCE, Volume 33, April 1979

foods in stomach contents; Alan Ziegler ofthe Bernice P. Bishop Museum for assistancewith the reptile collections; and Alan Ziegler,Allen Greer, and Sean McKeown, the latterof the Honolulu Zoo, for critical reviews ofthe manuscript.

LITERATURE CITED

.BAKER, K. 1976. The occurrence and ecolog­ical significance of metallic skinks on theislands of Hawaii and Kauai. Proc. 1stConf. Nat. Sci., Haw. Vo!. Nat!. Pk.;Coop. Nat!. Pk. Res. Studies Unit, Depart­ment of Botany, University of Hawaii,Honolulu, pp. 11-17.

BRONGERSMA, L. D. 1942. Notes on scincidlizards. Zoo!. Med. 24(1-2): 125-152.

BROWN, W. C. 1953. The distribution ofterrestrial reptiles in the islands of thePacific basin. Proc. 8th Pac. Sci. Congr.;Vo!. lIlA, Oceanography and Zoology;Nat. Res. Council of the Philippines,University of the Philippines, Quezon City,pp. 1479-1491.

COUZYN, D. 1973. Key to Hawaiian skinks.Div. Vert. Zoo!., Bernice P. Bishop Mus.,Honolulu. Typescript. I p.

FISHER, H. I. 1948. Locality records of Pacificisland reptiles and amphibians. Copeia I(Apr. 15): 69.

GREER, A. E., JR. 1974. The generic relation­ships ofthescincid lizard genus Leiolopismaand its relatives. Aust. J. Zoo!., Suppl. Ser.31: 1-67.

HUNSAKER, D., and P. BREESE. 1967. Herpeto­fauna of the Hawaiian Islands. Pac. Sci.21 (3): 423-430.

LACK, D. 1954. The natural regulation ofanimal numbers. Oxford University Press,London. 343 pp.

LOVERIDGE, A. 1939. A new skink (Leiolo­pisma hawaiiensis) from Honolulu. Proc.BioI. Soc. Wash. 52(Feb. 4):1-2.

OLIVER, J. A., and C. E. SHAW. 1953. Theamphibians and reptiles of the HawaiianIslands. Zoologica 38(2, no. 5): 65-95.