Herpetofauna of the Hawaiian Islands!

DON H UNSAKER 112 and PAUL BREESE3

THIS STUDY was undertaken to determine thechanges that have occurred in the herpetofaunaof the H awaiian Islands since the work in theearly forties by Oliver and Shaw ( 1953). Thework is a result of a field survey of most of theislands conducted by the authors dur ing thesummer of 1962. Since the purpose of the sur­vey was to observe gecko vocalization, moredata are available on this group than on theothers. The islands afford a unique opportunityto observe a dynamic fauna since there are con­stant introductions from foreign sources. Peri­odical surveys have been made which furn ishan investigator a well annotated history.Changes have been observed dur ing each of themajor surveys, made by Stejneger ( 1899), Sny­der ( 1917), and Oliver and Shaw ( 1953).

In an accurate analysis of the faunal charac­teristics of the islands during 1943 when theirstudy was conducted, Oliver and Shaw (1953) ,listed 8 species of amphib ians and 15 species ofreptiles. Since that time the house gecko, H emi­dactyl«: [renatus, has been introduced. Twoiguanid lizards, the Cuban anole, Anolis por­cains, and the horned lizard, Phrynosoma cor­ntttnm, have become established and are nowconsidered to be permanent residents of theislands. Anolis was established by 1951 (Shawand Breese, 1951) and Pbrynosoma since thattime. H awaii's laws prohib it introduction of anysnakes, but occasional specimens have been col­lected. Gopher snakes, Pituopbis catenijer, andgarter snakes, Thamnoph is elegans, have beencollected on Oahu, but are not considered to beestablished. These probably represent pets thathave escaped and at the present time do notconstitute a significant part of the fauna.

! Thi s research was suppo rted in part by the N a­tional Inst itut es of Health , Grant N o. M-4996. Man­uscript received April 18, 1966.

2 San D iego State College, San Diego, Californi a.3 Formerly Di rector of Kapiolani Park Zoo, Hono­

lulu , H awaii.

REPTILIASERPENTES (SNAKES )

Blind Snake (Typhlops braminus )

About 1930 this species was accidentally in­troduced on the island of Oahu with a shipmentof palm trees from the Philippines which wereplanted around the new Kamehameha Schoolsin Kapalama, Honolulu. It became establishedquickly in the vicinity of the schools, and dur ­ing the following decade spread into the resi­dent ial areas of Honolulu . By 1947, it had beencollected in an area several miles from theoriginal locality ( Fisher, 1948 ) , and it nowappears to occupy the lowland area over theenti re island . It is unkn own on the highermountains, but this may be due to inadequatecollecting efforts. The large amounts of top soilthat are transported from one part of the islandto another probab ly are responsible for thespread of this fossorial animal. Recently, T yph­lops braminus has been collected in Kahului,the major port city of the island of Maui. Whilethere are some restrictions on the transportationof soil around vegetation or domestic plantsbetween the islands, certain people manage toevade them. Such shifting of top soil, pottedplants, etc., as well as large-scale freight ship­ping by sea, probably is responsible for the in­troduction of the blind snake on Maui . Itsestablishment on the other islands is to be ex­pected.

SAURIA ( LIZARDS)GEKKONIDAE

M Ol/l'lling Gecko (Lepidodactylus lugubris)

The first Hawaiians probably introduced thisspecies during early population invasions ap­proximately 1,000 years ago. The eggs arehighly adhesive and can be seen clinging tomats and other household articles such as earlyimmigrants probably brought with them. Theyhave been recorded in the Panama Canal Zone

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by Smith and Grant (1961), undoubtedly in­troduced by this method of egg transport. Todaythe species is found throughout the islands,from remote forests to the downtown areas ofthe largest cities. It is the most frequently ob­served lizard and is well represented in collec­tions because of its gregarious habits, little fearof humans, and population concentration inareas inhabited by people. This common geckoapparently has adapted itself with great successto living in close association with hum ans. It isa common observation that these geckos occurin greater numbers in well populated areas thanin more remote sections. Of a series of 21 indi ­viduals collected in a transect from an uninhab­ited area into a city, 10 were collected in a pop­ulous section, 5 from the fringe area, and 6from the uninhabited area. In making this tran ­sect an attempt was made to maintain a con­stant unit of effort in each of the three habitatsduring the collections. The great number ofnumerous species of nocturnal insects att ractedby the electric lights of the city probably is re­sponsible, in large part, for the large geckopopulati on in the city. This does not explain ,however, the abund ance of geckos in or nearman-made structures that were remote from anylighted areas. In nonurban areas, they are defi­nitely associated with open forests rather thanwith densely forested areas.

Observations of several individuals indicatethat L. IlIgllbris is rather sedentary and that thehome range usually does not exceed an area of6 or 8 ft in diameter. H owever, these lizardsperiodically migrate from one area to another.These movements are not a coordin ated groupeffort, but appear to be a simultaneous evacua­tion of the normal home ranges of many indi ­viduals . During these periods, individual geckoshave been seen moving across walls, down treetrunks , over sidewalks, etc. Such periods of ex­cessive activity have not been correlated withseason, rainfall, temperature, or other factors.

L. IlIgllbris is active from shortly before darkuntil sunri se. Although highly gregari ous, theyshow some aggression toward each other. Achirping noise is utili zed in social behavior anda squeakin g occurs during painful or aggressiveencounters. T ail-waving has been observed insocial interactions. The females are slightl ylarger than the males. The mean snout-vent

PACIFIC SCIENCE, Vol. XXI, July 1967

length of 26 females was 41.69 mm, rangingfrom 33.0 to 46.7 mm. The mean snout-ventlength of 7 males was 35.96 mm, ranging from32.2 to 42.4 mm.

T ree Gecko (Hemiphyllodactylus typus typus)

N o significant changes have appeared in thedensity and distribution of this species since1943; it remains rather rare. Of 161 geckoscollected in Kailua on Oahu, only 5 were of thisspecies; 4 of them were collected on th e sidesof buildings in the city and 1 from under thebark on a tree. They are extremely agile andwary lizards and it is much easier to collectthem from the sides of buildings than fromtree trunks. Hence we do not believe that ourlarger collection fr om the city buildings neces­sarily implies a larger population there .

H. typllS typlls is not a gregarious species;only 1 individual was collected from a well­lighted building which supp orted over 80 othergeckos. On a darkened building about 30 ftaway, 2 other individuals were collected about10ft apart. The only lizard found in closeassociation with the tree gecko was the housegecko.

H ouse Gecko (Hemidactylus frenatus)

This species is the latest addition to the her­petofauna of the Hawaiian Islands (Hunsaker,1966) . It was first observed in June 1951 inthe city of Kailua, about 20 miles north ofHonolulu . It is well established at the presenttime and appears to be rapidly replacing bothHemidactylns garnoti and Lepidodactylus Il/glI­bris in the cities on Oahu. H . t rella/tiS can beidentified easily by the series of enlarged scaleswhich encircle the tail , exhibiting concentriccircles of short spines (Fig. 1) . These circlesare separated by normal scales. This species hasa cylindrical tail and lacks the lateral folds andloose femoral skin of H . garnoti. H . [renatus isvery similar to the fox gecko in size and color,but it is much more aggressive. N ot uncom­monly it attempted to bite the collector.

Mixed colonies of H. gamoti and H . [renatnsare rare. Apparently the new immigrant is muchmore successful a competitor than are the otherspecies of geckos. This factor, and its greateraggressiveness, apparently are responsible for itsrapid replacement of the fox gecko in urban

H erpetofauna of Hawaii-HuNSAKER AND BREESE 425

FIG. 1. Hemidactylus [renatus.

areas. H. [renatus has not been collected inareas removed from hum an habitation. In atransect which extended from an uninhabitedarea into the city of Kailua, 5 H . gamoti werecollected in the uninhabited area and only 1 inthe city proper. Conversely, 40 H. [renatns werecollected in the city and none in the periph eralareas. Very few mourning geckos were foundto be associated with H . [renains. In KualaLumpur, Malaya, H . [renatas is quite commonin the inhabited areas and L. 11lgllbris is muchmore difficult to collect in the fringe areas. Inthe past, the well-lighted resident ial areas ofHonolulu have been occupied by L. lttg1lbrisand the invasion of this habitat corresponds withfindings of Church and Lim (1961 ) , who statedthat in Bandu ng, Java, H. [renatns preferredresident ial areas which were well-lighted anddamp. In an area that has been under observa­tion for the past few years, the disappearance ofthe fox gecko and the mourn ing gecko popula-

tion coincided with the appearance of th is spe­cies. These large geckos appear to have a homerange of an area about 12- 15 ft in diameter.They are highly vocal and a distinctive series offive or six call notes can be heard up to 100 f taway. Aggressive or painful situations may pro­voke a prolonged squeak. This species occurredin close association with the stump-toed gecko(Peropus 1711Itilatlls). H. frenatlls were observedin Kailua, in many parts of Honolulu , aroundthe International Airport, and in the wharfarea. Four ind ividuals of this species were col­lected only in the harbor areas of Kahului onMaui, while H. gamo ti and L. Il/g1lbris werecollected in other sections of the city. This dis­tribution indicates that H . frenatttS has arrivedonly recently on Maui , N one of these lizardshas been collected on any other island . This isa large species; the largest individual collectedwas a male 58 mm in snout-vent length.

The current distributi on of H . [renntus indi -

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cates that it is quite successful in establishingitself in new areas. The species is very wide­spread in the Orient and in the Malay States.Grant (19 57) recorded it from Acapulco, Mex­ico; Tanner on Saipan in 1948; in 1950 it wasrecorded from Morotai; Church and Lim( 1961) recorded it in Java; Larry Richards col­lected it from Guam in 1947. In all probabilityrepresentatives of the Mexico population weretransported by early traders, and the recentrange expansion is due to equipment and ma­terial shipped during W orld War II.

Fox Gecko (Hemidactylus garnoti)

The futu re of this species in the islands willbe interesting to follow. At the present time itis uncertain whether H. frenatus is replacingthis species in unpopulated areas. If the foxgecko is better adapted to living in forestedareas, it will probably continue its existence inthis habitat. If the house gecko is as efficientin displacing the fox gecko in remote areas asit is in the cities, the futu re of this long-termresident is questionable. The fox geckos havebeen established for many years and probablyare one of the earliest inhabitants of the islands.In Malaya, there are areas where both H . gar­noti and H . frenatus live in close association,and so it is possible that the two species willcontinue to be sympatric in Hawaii's fauna.

Of 12 eggs from the island of Hawaiiwhich were laid durin g the last week of June,the largest was 17.0 X 8.9 mm, the smallest9.4 X 8.7 mm. These measurements comparewell with those of eggs of the same species re­corded by Cagle ( 1946) for eggs from a popu­lation on Tinian (which had a mean of 12 X 7mm) . Measurements made 2 weeks later didnot indicate a significant change in size. Ofthe 12 eggs 7 hatched, and the mean snout­vent length of the newborn lizards was 24.08mm, the mean total length , 48.0 mm. Therange of snout-vent length was 26.0-22.5 mm;the range of total length was 51.0-45 .5 mm.These measurements are well within the rangequoted by Snyder ( 1917) for Hawaiian popu­lations: 39.5-56.0 mm total length .

The maximum incubation period for eggslaid in Hawaii and hatched at room tempera­ture (74° F) was 64 days. Cagle ( 1946)

PACIFIC SCIENCE, Vol. XXI, July 1967

hatched a series of eggs of this species III a45-day incubation period.

Stu mp -T oed Gecko (Pe ropus mut ilatus)

There appears to be no significant changein the distribution of this gecko. It occurs inrather dense populations in some areas and isscarce in others. It is found away from thecity of Honolulu in the back country and isquite common at the International Airport onOahu. Females are slightly larger than the males.In a series of 17 females measured, the meansnout-vent length was 45.60 mm, with a rangeof 39.5- 55.5 mm; for 34 males, the meansnout- vent length was 43.65 mm, with a rangeof 29.0- 57.5 mm.

IGUAN IDAE

Gray Cuban Anole (Anolis porcatus)

This species is well established on Oahu atthe present time. Both large adults and im­mature forms are commonly seen in Honolulu.The original site of collection was in the Kai­muki section of H onolulu . It has spread toother nearby sections of the city and to ManoaValley, and is presently established on the northside of the island, at Kailua. The first intro­ductions were probably imported pet lizardswhich escaped. W e can consider this speciesto be a permanent member of the fauna ofOahu. It has not been collected from the otherislands.

T exas H om ed Lizard ( Phynosoma cornutum)

An increasing number of reports and ofspecimens collected indicate that this speciesis probably established as a permanent residentof the Hawaiian fauna on the island of Oahu.These animals undoubtedly originated fromescaped pets . They have been found from theslopes of Diamond Head throughout Honoluluto the xeric areas above Pearl Harbor. N o con­crete evidence has been obtained to indicatethat a reproducing colony has been established,with eggs and hatchling lizards. Probably thislizard is reproducing, since immature speci­mens have been obtained from the islands, andthe 10 or 15 reported is an unusually high

Herpetofauna of Hawaii-HuNSAKER AND BREESE 427

number to be accounted for by the escape ofpet lizards.

SCINCIDAE

Snake-Eyed Skink (Ablepharusboutoni poecilopleurus)

N o important changes have occurred in thepopulati on of this species. It is still rather com­mon in some of the more arid sections, butit occurs in definitely localized populations. Insome areas it is absent, although the environ­ment is similar to that of other areas wherethe skink is common.

M oth Skink (Lygosoma noctua noctua)

At the present time, the moth skink is foundonly in a small area on the northern coast ofOahu , near Kahuku Point. There seems to belittle doubt that the rapid expansion of Lygo­soma metallicum is responsible for the decreasein the once large populations of the moth skink.The area in which it now occurs is similar tolarge areas of Oahu which are now occupiedby the metallic skink and at one time wereoccupied by L. noctua. The increase in amountof land under cultivation has not been greatenough to account for the reduction that hasbeen observed. N o data are available for popu­lations once observed on Hawaii, Kauai, andMaui .

Metallic Skink ( Lygosoma metallicum)

Few animals have been so successfully intro­duced as was the metallic skink on the islandof Oahu. Its rapid multiplication on this islandhas produced remarkable numbers in the lowerareas. It is agg ressive with individuals of themoth skink, and it is certainly unafraid ofhumans . The success of the species probablyis due in part to its apparent lack of fear ofhumans . It is easy to approach these lizards,and they can be found close to human habi­tations. The species is still known only fromOahu.

AMPHIBIA

Gold and Black Poison Frog(Dendrobates auratus)

This frog has been limited in its distribu­tion only to the sites where it was released.

It was originally introduced in upper ManoaValley in 1932. This site now has a well-estab­lished population of frogs which extends tolower parts of the valley during the rainyseason. Additional plantings with subsequentestablishment have been made in WaiaholeValley, and the population has been observedto fluctuate in size at this locality, again accord­ing to the amount of water available.

Bull Frog (R ana catesbeiana )

This frog is extremely prolific and is wellestablished on all major islands. N o majorchanges in the populations have appeared sincethe 1940s.

Green Frog (Rana clamitans)

Since its introduction on Oahu in 1935, nogreat expansion of the population has beenevident. It is not common anywhere on Oahuand has not been repor ted on other islands.

Wrinkl ed Frog (Rana rugosa)

This species is well established and is quitecommon in some areas. The population sizevaries with the amount of rainfall available.During 1962 the populations of most amphib­ians were reduced to half the numbers foundin 1961, when surface water was much moreplentiful.

M arine Toad (Bufo marinus)

This species is found on all the major islandsand is the commonest species of amphibian.

SUMMARY

A survey of the herpetofaun a of the Ha­waiian Islands was conducted during 1962 todetermine any changes that might have oc­curred in the previ ous 20 years. New faunalspecies which have become established areAnolis porcatus, int roduced in the late 1940s;Pbrynosoma coronutum, introduced about 1955;and H emidactylllS [renatns, first observed inJuly 1961.

Other species have extended or contractedtheir ranges, but no other significant changeswere observed. It was noted that populationalvariations in amphibian s could be attributedto annua l changes in available surface moisture.

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The house gecko, H emldactylus [renatus, israpidly increasing in numbers and is appar­ently being introduced into the other islandsfrom Oahu . The most important means of intro­duction appears to be by the movement of boatcargoes from one harb or to another.

REFERENCES

CAGLE, FRED. 1946 . A lizard population onTinian. Copeia 1946 :4-9.

CHURCH, G., and L. C. LIM. 1961. The distri­bution of three species of house gecko inBandung (Java). Herpetologica 17 :199­201.

FISHER, H . 1948 . Locality records of Pacificisland reptiles and amphibi ans. Copeia 1948 :69.

GRANT, C. 1957. The gecko H emidactylus

PACIFIC SCIENCE, Vol. XXI, July 1967

[renatus in Acapulco, Mexico. Herpetologica13:153.

HUNSAKER, D . 1966. Population expans ion ofthe house gecko, H emidactylus [renatus.Philippine J . Sci. 95.

OLIVER, J., and C. SHAW. 1953. The amphib­ians and reptiles of the Hawaiian Islands .Zoologica 38 :65- 95.

SHAW, c., and P. BREEZE. 1951. An additio nto the herpetofauna of Hawaii. Herpeto­logica 7 :68.

SMITH, H. M. , and C. GRANT. 1961. Themourning gecko in the Americas. Herpeto­logica 17 :68.

SNYDER, J . O. 1917. Notes on H awaiian liz­ards. Proc. U. S. Natl. Mus. 54 :19-25.

STE]NEGER, L. 1899. The land repti les ofHawaiian Islands. Proc. U. S. N atl. Mus .21 :783- 813.