No abstract

No abstract

The results of terrestrial vertebrate collecting on the Krakatau Islands, Sunda Strait, during La Trobe University-L.I.P.I. expeditions in 1984, 1985 and 1986 are reported and previous records from the islands are consolidated and reviewed. Since the 1883 eruption of Krakatau, 15 species of terrestrial vertebrates (13 reptiles and 2 mammals) have been recorded from the Krakatau Group. Two of the species records ( Crocodylus porosus and Cosymbotus platyursare only incidental but the remaining thirteen species have at some stage established breeding populations on one or more islands. In the first 50 years up to 1933, ten species (eight reptiles and two mammals) reached the islands, eight of which ( Hemidactylus frenatus, Lepidodactylus lugubris, Emoia atrocostata, Mabuya multifasciata,Varanus salvator, Python reticulatus, Rattus rattus and Rattus tiomanicus ) had established breeding populations. Results of collections made over the period 1982-1986 showed that two of the species (L. lugubris and E. atrocostata) with breeding populations in 1933 had become extinct, whereas five new species ( Gekko gecko, Gekko monarchus, Hemiphyllodactylus typus, Chrysopelea paradisi and Ramphotyphlops braminus ) have reached the islands and established breeding populations. Therefore at the end of 100 years, eleven species of terrestrial vertebrates have extant breeding populations on one or more islands in the Krakatau group; two species have become extinct; and two species have incidental records. Significant ecological changes in the development of the present day terrestrial fauna are discussed. These include canopy closure of the forests and continual marine erosion of the coasts that together have eliminated most of the open habitats on Rakata, Sertung and Panjang; heavy ash falls from volcanic eruptions on Anak Krakatau that have periodically disrupted successional stages and habitats on Sertung, Panjang and Anak Krakatau. The dispersal of terrestrial vertebrates in the Sunda Strait is discussed in the light of the heavy boat traffic and the predominant southwest ocean currents. It is concluded that dispersal by human agency on boats is highly significant, seven of the 15 recorded species (46%) being most likely to have reached the islands in this way; and the prevailing southwest flow of water in Sunda Strait makes Sebesi and Sumatra the probable source areas for the eight species most likely to have dispersed on ocean currents by swimming or rafting. Anak Krakatau, the volcanic island that became permanent in Aug. 1930, has three species of terrestrial vertebrates ( H. frenatus, V. salvator . and C. paradisi ) all of which have established breeding populations on Rakata, Sertung and Panjang. The early arrival of H. frenatus and V. salvator and their present abundance on all four islands distinguishes them as the most successful terrestrial vertebrate colonizers of the Krakatau group.

The type species of the genus, ceri (Lucas-I J. Kinghom, 1929. is placed in synonymy. A-Pseudem w pa , is described for the genus which was gbt mono:>pic. The ecology and distribution of each species is discussed.

An examination of cases of turnover in animal species on the Krakataus since 1883, particularly vertebrates, supports the findings of plant ecologists that very little, if any, turnover is stochastic. Successional, rather than equilibrium turnover is still occurring in all animal groups for which analyses can be made; for no group of animals is there evidence that an equilibrium of species number has been achieved, although for resident land birds there are indications that this is now imminent. Approach to equilibrium is not uniform; the colonization curves for resident land birds, reptiles, cockroaches and nymphalid and hesperiid Lepidoptera, as examples, have flattened markedly in the past 50 years, whereas numbers of species of land molluscs and many other insect groups are still increasing at a rate similar to that in the first half century since 1883. The period of the beginning of forest formation (1908-21) was the time when immigration reached a peak, and the period of canopy closure (1921-33) was the time of highest extinction rates. Successful colonists, over a range of animal groups, appear to be species with wide distributions and broad ecological tolerances. There is indirect evidence that successional processes have precluded colonization by several animal groups present in the mainland pool because of unavailability of their preferred habitat, and it is suggested that the effective available pool, as opposed to the theoretical one, changes in size and species complement as succession proceeds on the target islands. We believe that the brief open-habitat phase was too short for the establishment of several animal groups that were available in the pool. Animals of mature forest are, in general, absent as the archipelago’s forests are still relatively impoverished and early successional. Anak Krakatau, in general terms, offers an analogy with the early decades of colonization after 1883. The role of animals in the first stages of forest diversification from casuarina woodland has been monitored on this island, and an ash-lava aeolian ecosystem based on an allochthonous energy source was identified, which parallels similar systems on volcanic substrates in Sicily, the Canaries and, particularly, the island of Hawaii.

ABSTRACTand a physically dynamic, ever-young spit on Sertung I, also held at an early successional stage, may provide (i) ecological refuges for some species whose optimal habitat on the older islands is being extirpated by vegetational succession and (u) ecological "windows" through which such species may still establish from the mainland, thus postponing their extinction on the archipelago.The 1883 eruption of Krakatau Island (Krakatoa) resulted in the loss of some two-thirds of the island and extirpated the flora and fauna of its 813-m-high remnant, Rakata (now 777 m), and the adjacent islands Sertung and Panjang (1) (Fig. 1). (6) and by us from 1984 to 1986, so that two good datum points (1951-1952 and 1984-1986) are now available for birds, in addition to those used by MacArthur and Wilson, and one more (1984-1986 for birds and bats, 1982-1986 for reptiles and rats), the first since 1933, for other vertebrates. It is now possible to reassess the course of recolonization by vertebrates, including the last half-century.In 1930 a new island, Anak Krakatau, emerged from the submarine caldera of Krakatau, and lava flows in the 1960s ensured its permanence. It is now 195 m high and still active. Successive eruptions since its appearance have set back biotic succession, and we believe the existence of Anak Krakatau has had a significant effect on the course of succession and species turnover on the archipelago as a whole.In our surveys ofthe archipelago in August and September, 1984-1986, we censused nonmigrant nonmarine birds by mist netting [21,677 (rain-free hours of daylight during which the nets were set) X (M2 of net)], broadcasting calls of expected species, recording calls and songs, 411 man-hours of visual survey, and 63 man-hours of spotlighting. Bats were detected by ultrasound (19 man-hours) and captured in mist nets [7675 (rain-free hours of night during which the nets were set) X (M2 of net)] and harp traps (34 trap-nights). Reptiles were caught 515The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Two species of scincid lizard, both hitherto identified as Leiolopisma pretiosum, occur syntopically on Mt Wellington, near Hobart, Tasmania. One of these is conspecific with the holotype of Mocoa pretiosa O'Shaughnessy, 1874. while the other is conspecific with the holotype of Mocoa microlepidota O'Shaughnessy, 1874, which has been regarded as a synonym of L. pretiosum since 1887. The two species are redescribed as members of an endemic Tasmanian subgroup within the Australian radiation of the genus Leiolopisma (sensu Greer 1982). Leiolopisma microlepidotum is confined to disjunct alpine populations in the south and west of Tasmania. It differs from L. pretiosum in colour pattern, larger size and more robust, less depressed head and body. Aspects of the biology and ecology of these and other Tasmanian endemic Leiolopisma species are also discussed.

Apart from feral pigs on Panjang, rats ( Rattus rattus and Rattus tiomanicus ) and bats (various families, genera and species) are the only mammals resident on the Krakatau Islands. The two species of rat occur on separate islands, R. rattus on Rakata and R. tiomanicus on Panjang and Sertung. Both occur on Java. Of the two genera of bats examined, species of Cynopterus were found on Java and all the Krakatau islands, whereas Myotis muricola muricola was detected only on Java and Rakata. The main faecal bacteria of these mammals were shown to be Escherichia coli and species of Klebsiella , Enterobacter and Citrobacter , with other bacteria (e.g. Proteus sp., Pseudomonas sp., Aeromonas sp., Serratia sp., Proteus/ Providenca sp., Morganella sp. and Streptococcus faecalis ) being present in only a minority of individuals Significant differences were noted between the faecal floras of the two rat species. E. coli was always present in R. rattus , but was less frequent in R. tiomanicus (p < 0.05), whereas species of Klebsiella and Citrobacter were less frequent in R. rattus than in R. tiomanicus (p < 0.05). Differences between the faecal floras of the two bat genera were less significant, with the four main faecal bacteria being present in each genus. However, some individual M. muricola muricola yielded S. faeclis, Morganella sp. and Proteus/Providencia sp. whereas species of Cynopterus did not ( p < 0.05). S. faecalis was detected in rats and the bat M. muricola muricola on Java, but not in mammals on the Krakataus. This may be related to the absence of humans and their domesticated animals on the Krakatau islands. Only on Java did rats carry tetracycline-resistant E. coli or tetracycline-resistant species of Klebsiella . This may be related to the widespread use of tetracycline by humans on Java, where tetracycline is available without medical supervision. Isolates of E. coli from rats on Panjang were more resistant to chloramphenicol than were E. coli isolated from rats on the other islands of the Krakatau group, and isolates of Klebsiella from bats on Panjang were more resistant to sulphamethoxazole than were Klebsiella species isolated from bats on Rakata. The reason for faecal bacteria from Panjang mammals being more antibiotic resistant than those from mammals on other islands of the group is unclear, but may be related to differences in diet and vegetation, or the presence of feral pigs on Panjang only.