War in the Pacific
Archelogy and History of Guam
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2. The Biological Settings Ecological Associations Flora and Fauna

Uncleared or more or less naturally revegetated portions of Guam are covered mostly with (1) typical beach growth along the coasts, the strand flora association of largely Indo-Malayan species with coconut palms predominating, with tall and small shrubs, and low vines, especially a blue-flowered morning-glory (presumably the goats-foot convolvulus, Ipomoea) with occasionally various trees of types mentioned below for other communities (the plant variously identified as Scaevola fanflower or beach magnolia, or Messerschmidia argentia, velvet leaf tree, which covers much of Wake Island occurs here, but not in abundance); (2) at fairly low elevations above the coasts and inland, stretches of mixed brush with a variety of trees, mostly small hardwoods; or of virtually pure stands of tangantanga (Lucaena glauca) an acacia-like small tree or tall shrub, or tangantanga interspersed with occasional breadfruit (Artocarpus) coconut palms, Casuarina (the "Australian pine" or "Polynesian ironwood"), etc.; and patches of bamboo thickets with little else between; (3) upland forest remnants or secondary forest growth, in the limestone plateau — surviving ifil trees (Intsia) and other tropical hardwoods, and dense tangles of second-growth jungle; and (4) the extensive grasslands on the red volcanic soil of the southern hills and slopes, consisting of swordgrass (Miscanthus) with patches of woods, including much Pandanus, along tops of ridges, or with scattered Casuarina trees (found also in the first and second types).

Other plant communities of more limited extent include occasional mangrove clumps in protected coastal locations, and the extremely interesting upper strand flora: "Vines, short coarse grass, and low shrubs, a treeless association occurring on thin rocky soils at the top of seaside cliffs within range of salt spray. Most highly developed along exposed eastern coasts." (Bowers, p. 211, in Freeman, ed., 1951).

On lower slopes of the high cliffs along the eastern coast of Guam, however, the biotic community appears more like (3) above, with ifil (Intsia), pu-ting (Barringtonia speciosa) the palomaria (Calophyllum of the mangosteen family, an extremely hard wood), chopag (Ochrocarpus a smallish tree with oval green leaves like the pu-ting; pinkish flowers, I am told, and no fruit or nut), and other tropical hardwoods; the fadang or "federico palm" (actually a cycad, Cycas circinalis a source of sago but not utilized therefor in Guam, though the nuts are used), banyans (Ficus), and various smaller plants.

Of 545 species of ferns and flowering plants on Guam, 314, or 85%, were introduced by man, according to Dr. E. D. Merrill; and the presence of 231, or 42%, is due to accidental distribution. Only 61 species, or 11% of the total, are endemic (locally developed significant variations). More than 80% are species found also in the Philippines. There are 47 species of ferns, according to Dr. L H. Bryan (Guam Recorder, XIII, 1937).

Several of the common food plants, such as yams, taro, the federico cycad, and the breadfruit tree, and probably the coconut palm, were no doubt brought in by the original settlers, or at least by pre-Spanish natives. Many other crop plants were introduced by the Spaniards, or specifically by the Jesuit missionaries, after 1668, notably from America — pineapples, sweet potatoes (probably not pre-Spanish here, as was the case in at least certain Pacific islands), corn (maize), manioc (cassava; tapioca), tomatoes, papayas, peppers (Capsicum), cacao (chocolate), as well as tobacco.

Other plants of special interest or importance include the nipa palm (Nypa fruticans introduced from the Philippines for its leaves, used as thatch, according to Safford), the kapok or cotton tree (Ceiba not a true cotton), betel-nut (Areca), the orangeberry or limonchine (Triphasia) the Polynesian arrowroot (Taccapin natifida not recognized or pointed out to me, but listed for the island), and the species of Pandanus, Wild bananas (Musa), papayas, mangoes, breadfruit, and other "feral" fruit trees, in addition to many coconut palms, occur.

There have been extensive changes in the vegetation of Guam in addition to those brought about by deliberate artificial clearing of land for living and farming purposes and, in recent years, for large military installations, highways, and new settlements, and cutting of wood (the tropical hardwood trees of the northern plateau are mostly gone). In a report of a geological survey report of Guam in 1937, Dr. H.T. Stearns remarks: "It is probable that forests were originally more widespread on the volcanics [the southern half of the island] than now. Continued burning and the cultivation of the areas underlain by these rocks have reduced the humus, soil fertility, and thickness of the soil to such a degree that little else but ordgrass can live."

The annual burning of the grassland hills continued into modern times: see the editorial deploring the practice in the Guam Recorder, VI, No. 3, June 1929. Probably the swordgrass (Miscanthus) cover is continuing to extend itself; a detailed study of surviving plant communities and of current ecological changes on Guam would be of very great interest.

The most valuable single reference on the foregoing would be Safford's Useful Plants for check-lists, see E. D. Merrill, "An Enumeration of the Plants of Guam," Philippine Journal of Science 9: Bot., 17-155, 1914 (not seen) and E. H. Bryan, Jr., "The Plants of Guam," Guam Recorder, XIII, 1936-37; for concise and meaningful interpretations, Neil Bowers' chapter in Freeman (ed.), Geography of the Pacific World, New York (MacMillan), 1946. Other important general references include E. D. Merrill, Bibliography of Polynesian Botany, 1773-1935, B. P. Bishop Museum Bulletin 144, Honolulu, 1937; H. Kanehira, Flora Micronesia, Tokyo, 1933 (not seen); L. Diels, "Beitrage zur Flora von Mikronesien und Polynesien," Botanische Jahrbuch 52-69, 1914-1938 (not seen). For other pertinent references, see: E. D. Merrill, A botanical bibliography of the islands of the Pacific, with A subject index by E. H. Walker, Contributions from the U. S. National Herbarium, Vol. 30, Part 1, U. S. National Museum, Washington, D.C., 1947.

The indigenous vertebrate fauna of Guam, other than a great variety of birds, was extremely limited, consisting only of two species of bats, [1] a little worm-like snake (Typhlops), a few very small lizards [2] (few in species, abundant in numbers, or at any rate quite common) and the large lizard (Varanus indicus, locally called "iguana," as I understand is the case also in the Philippine Islands — not an iguanid, but a monitor lizard; up to about four feet long, greenish with yellow spots — now scarce on Guam, but common on Rota).

Forty-five species of birds were listed by Dr. E. H. Bryan in 1936, including albatrosses, petrels, cormorants, frigate birds, herons and bitterns, ducks, megapodes (none left on Guam?), rails, snipes, plovers, gulls and terns, pigeons, cuckoos, swifts, kingfishers, warblers, flycatchers, starlings, crows, white-eyes, and honey-eaters. [3] There are no land- (tree-) dwelling birds of prey regularly resident on Guam. [4] Insects [5] and other small invertebrates [6] have undoubtedly been varied and numerous at all times, since before the arrival of people.

The first inhabitants brought no livestock, not even pigs, and apparently not even dogs — at least the Chamorros had no dogs in the sixteenth century. The same was true of the Palaus, apparently, as late as the eighteenth century (pp. 30-31, 300, An account of the Pelew Islands, composed from the journals and communications of Captain Henry Wilson and some of his officers who, in August 1783 were there shipwrecked in the Antelope, a packet belonging to the Honourable East India Company, by George Keate, Esq., F.R.S., London, Second Edition, 1788). Rats and mice perhaps may have accompanied the Chamorros to the Marianas; this point — pre-Spanish occurrence here of rats — appears to be uncertain.

The Spaniards brought pigs, horses, cattle, carabaos, goats, turkeys and chickens, dogs and cats, certainly also rats, and the Philippine spotted deer, Cervus mariannus Desm., or Cervus philippinus, [7] introduced by Governor Mariano Tobias in the 1770's.

The only new animals of American importation during the first half of the twentieth century would seem to be improved varieties of livestock, particularly dairy cattle. The honey bee, now occurring wild, was introduced from the Hawaiian Islands in 1907. Feral dogs, pigs, and particularly cats, are found, and already were on Guam by 1905 (Safford) and at least on Tinian about 1860 (Delacorte's memoirs, cited below).

Ring-necked pheasants (Phasianus colchicus were released by U. S. Navy personnel on Guam in 1945; the only one I saw in January-February 1952 was dead. Previously, the Painted quail (Coturnix chinensis lineata had been brought in from the Philippines, by a Spanish officer in 1894, it is reported. This introduction was successful; several Painted quail were recorded in 1945, and a few were seen on Guam in January-February 1952.

The large poisonous toads (Bufo marinus which are common in the southern Marianas were introduced to Guam in 1947, to keep down the insects; the monitor lizards are said to die from eating the toads.

In 1942-1944 the Japanese introduced into Micronesia the giant snail (Achatina fulica from East Africa, now a very serious agricultural pest. [8] These reached Guam only in 1946, it is stated; they are now extremely abundant there. The record Achatina shell to date, collected by Dr. Y. Yamashiro in January 1952, is 7-1/2 inches long.

At the end of the war, the birds were almost all gone; since 1944, however, they have been coming back gradually (a list of species tentatively or positively recognized in January-February 1952 is appended). [9] Monitor lizards are now scarce; only four were seen — briefly glimpsed — on Guam during this survey. There are comparatively few deer left; none was seen in the wild by us in January-February 1952 (a group of six deer is kept in captivity by a private individual on the beach drive north of Agana, not exploited or advertised but in full view).

Finally, the ocean about Guam, outside the fringing reef, is swarming with fishes of many kinds, [10] which were formerly utilized as an important source of food.


1. The flying fox or fanihi, a large fruit-eating bat, Pteropus mariannus (not markedly different from other species of Pteropus in the western Pacific); and a small insectivorous bat, Emballonura. SEE: T. D. Carter, J. E. Hill, and G. H. Tate, Mammals of the Pacific World, New York (MacMillan), 1945; and general references on Guam such as Safford's Useful Plants and Mrs. Thompson's Guam and Its People.

2. The little skink, Emoia cyanura, and four species of geckos, the commonest said to be Sapidodactylus lugubris. SEE: Arthur Loveridge, Reptiles of the Pacific World, New York (MacMillan), 1945, and general references on Guam (Safford's Useful Plants, Mrs. Thompson's Guam and Its People, etc.).

3. SEE: E. H. Bryan, "Birds of Guam," The Guam Recorder, May-October 1936; Ernst Mayr, Birds of the Southwest Pacific New York (MacMillan), 1945; T. M. Blackman, Birds of the Central Pacific, Honolulu (Tongg), 1944; Joe T. Marshall, "The endemic avifauna of Saipan, Tinian, Guam and Palau," Condor, 51:200-221, 1949; Rollin H. Baker, The avifauna of Micronesia its origin, evolution and distribution, University of Kansas Museum of Natural History Publications, Vol. 3, No. 1, Lawrence, 1951.

Incidentally, of the seven birds of the Pacific area among the animals listed by the 1949 technical conference, at Lake Success, of the International Union for the Protection of Nature, and designated for immediate attention as vanishing or seriously threatened species, two are endemic to the Marianas Islands — the Marianas mallard (Anas oustaleti) and the Marianas megapode (Megapodius laperouse). Both are now apparently extinct on Guam, the mallard being fairly secure on Saipan and Tinian (especially if Lake Susupe, on Saipan, is protected, as has been repeatedly recommended), but the megapode surviving only in the northern Marianas. SEE: Baker, 1951; Yoshimaro Yamashiro, "Notes on the Marianas Mallard," Pacific Science 2:121-122, April 1948; and Ernst Mayr, "Bird conservation problems in the southwest Pacific," Audubon Magazine, September-October 1945. The peculiar Guam rail, or "road chick" or "Guam quail," Rallus owstoni, concern for which has occasionally been expressed, is, however, abundant on the island at present.

4. Formerly, before the American period, the short-eared owl (Asio flammeus, syn. Asio occipitrinus) occurred on Guam, but none has been recorded in the twentieth century (Safford, 1906; Bryan, 1936; Baker, 1951). A few small hawks are among occasional or accidental visitors to the Marianas, however. Baker (1951, p. 217) cites a few records of the Asiatic sparrow-hawk (Accipiter virgatus gularis) on Guam, from 1887 to 1945; Dr. Bryan refers to the same bird (as the Variegated hawk, A. virgatus nisoides, a synonym according to Baker, 1951) as an occasional stray from East Asia, not collected on Guam since 1900. Baker notes that the Peregrine falcon (Falco peregrinus japonensis) was definitely observed on Guam in 1945. Each of these is a casual winter visitor to Micronesia (Baker, 1951). In addition, the Chinese goshawk (Accipiter soloensis) has been observed on Rota, as well as Yap, though not recorded for Guam itself (Baker, 1951, p. 104). Among the birds seen on Guam in January-February 1952, but not definitely identified, was one which, on brief and casual observation, distinctly resembled the accipitrine hawks, and presumably it was one of these. The large and well-known bird of prey, the Frigate-bird or Man-o'war bird (Fregattus was not observed.

5. SEE: O. H. Swezey and others, Insects of Guam, Vol. I and Vol. II, Bishop Museum Bulletins 172 (1942) and 189 (1946); for other pertinent references, see: B. H. Bryan, "Bibliography of Micronesian entomology," Pacific Science Board (mimeographed), Honolulu, 1946. Notable are the large and beautiful spiders, very common in the brush. The conspicuous and fairly common butterflies are not very different from species of the United States, including a swallowtail (Papilio xuthus) a Monarch (Danaus archippus), a Vanessa I believe, a handsome black species with blue spots (probably Hypolimnas?) and a small white one, very common, like our "cabbage" butterfly. Honey bees (feral, as mentioned in the text) and the black native bee (Lithugris guamensis) were encountered, possibly also leaf-cutter bees, Megachile spp.; Yellowjackets (Polistes macensis) and other, smaller wasps were seen. A moderate sized dragonfly is probably of the Pantala spp. reported as common; also recorded for Guam are large and colorful Anax spp. dragonflies. Mosquitoes (Culex sp.) are sufficiently numerous and blood-thirsty to be a nuisance.

6. No general reference on the various groups of invertebrates of Guam has been located or encountered. Technical papers or studies of particular groups include: E. H. Bryan, "Guam land shells," Guam Recorder, XIV, 1937 (about 50 species listed); and three citations not seen — R. Tucker Abbott, New syncerid Mollusks from the Marianas islands, Bishop Museum Occasional Papers, Vol. XIX, No, 15, 1949; J. C. Chamberlin, Three new species of false scorpions from the island of Guam, Bishop Museum Occasional Papers, Vol. XVIII, No. 20, 1947; R. V. Chamberlin, "A new milliped and two new centipeds from Guam," Proc. Biol. Soc. Wash. 59:161-163, 1946. Ant-lions, hermit crabs, and other miscellaneous small creatures appear similar to those in other parts of the world. The coconut crab (Birgus latro) is a particularly interesting — and rather delicious — land crustacean.

7. Cf. Sir Victor Brooke, F.Z.S., "On the deer of the Philippine islands, with the description of new species.," Proc. Zool. Soc. London, 1877 (pp. 51-60, Plates VIII-X). The genus or subgenus now used for the Philippine spotted deer (a small one, of the sambar type) is Rusa, but the general name Cervus still appears in general works, such as T. D. Carter, J. E. Hill and G. H. Tate, Mammals of the Pacific World, New York (MacMillan), 1945.

8. SEE the summary on pp. 7-8 of Economic Insects of Micronesia, Report of the Insect Control Committee for Micronesia 1947-48, compiled by E. H. Bryan, published by the National Research Council, Washington, 1949; and see technical papers by J. C. Bequaert and Albert R. Mead, published by the Museum of Comparative Zoology, Harvard (notably Bulletin, Vol. 105, 1-2, 1950).

9. Reef heron, Demiegretta (Ardea) sacra, white-tailed tropic-bird ("bos 'n bird"), Phaethon lepturus, White tern, Gygis alba, Guam rail, Rallus owstoni, *Wood sandpiper, Thinga glariola, Golden plover, Pluvialis dominica fulva, Edible-next swift, Collocalia inexpectata, Green fruit-dove, Ptilinopus roseicapilla, *White-throated dove, Gallicolumba xanthonura, *Crows, Corvus kubaryi, Dusky (Micronesian) starling, Aplonis opacus, Cardinal honey-eater, Myzomela cardinalis, *Kingfisher, Halcyon cinnamomeus, *Micronesian broadbill, Myiagra oceanica, Painted or Pygmy quail, Coturnix chinensis lineata (introduced), *Ring-necked pheasant, Phasianus colchicus (introduced)

*All these are quite, or fairly, common, except those asterisked; several unidentified birds, one each. Only one Ringnecked pheasant was noted, recently dead, in thick grass and vines. As to the crow, I am not even positive that I saw any, but at least one black bird glimpsed was definitely larger than the quite common Dusky starling (which is 9" long, while the Marianas Crow is listed at 15"). Only two Kingfishers were seen; one of them was in the wrong place — Marshall (1949) says that this species is not found in open shore habitats, but restricted to dense woodland and of secretive habits, while the conspicuous White-collared Kingfisher (Halcyon chloris of open habit and shore habitat is entirely lacking on Guam (but is seen on Rota; certain islands have only this latter, which still stays out of the woods; other islands have both) — but this was definitely a Micronesian Kingfisher, H. cinnamomeus, one of the few bird identifications on which I feel complete assurance, and he was sitting conspicuously on the fence at the Fr. Sanvitores shrine on Tumon Beach.

Not recognized were the Reed warbler, Acrocephalus luscinia, and the Bridled white-eye, Zosterops conspicilata, only reported for Guam but fairly common and important. The Chinese least bittern, Ixobrychus sinensis, was observed on Rota but not on Guam.

For many of these birds, or closely related forms, including the hawks, bitterns and herons, the painted quail, megapodes, rails, kingfishers, starlings, white-eyes, see also Jean Delacour and Ernst Mayr, Birds of the Philippines, New York (Macmillan), 1946.

10. SEE, among others, Henry W. Fowler, Fishes of Oceania, Bishop Museum Memoirs, Vol. X, 1928, and Supplements I, II and III Memoirs, Vol. XI, Nos. 5 (1931) and 6 (1931), and Vol. XII, No. 2 (1919); E. H. Bryan, "The fishes of Guam," The Guam Recorder, XV, 1938-1939.

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Last Updated: 14-Feb-2004