Proceedings of the New Zealand Society for Parasitology

Abstract

Publication of these abstracts does not preclude publication of the full papers elsewhere. Information regarding the work described should be sought directly from authors.     

The population ecology of Rattus exulans on Tiritiri Matangi Island,and a model of comparative population dynamics in New Zealand

Abstract

On Tiritiri, a small predator-free island in northern New Zealand, kiore (Rattus exulans) were live and snap trapped in grassland and forest. In both habitats, kiore abundance peaked in late summer/autumn. The increase followed a 3 month breeding season during which females produced two to three litters, each averaging 7 young. During the population decline in autumn and winter, animals lost weight. Few bred in the breeding season of their birth and none lived to breed in a second breeding season, so the population consisted of distinct age cohorts. These patterns may relate to a highly seasonal food supply.

Kiore elsewhere in New Zealand show seasonal breeding, but the length of breeding, sexual maturation, and litter size vary. Other studies of kiore in the Pacific show less marked seasonal fluctuations, longer breeding seasons, and smaller litters. We propose a model to explain the variation in rodent demography in New Zealand. The model is based on the seasonal availability of food, along with the modifying influences of predation and dispersal.     

Response of a Tree Weta Population (Hemideina crassidens) After Eradication of the Polynesian Rat from a New Zealand Island

Abstract A population of Hemideina crassidens (the Wellington tree weta) was monitored over a 4‐year period after the eradication of Rattus exulans (the Polynesian rat kiore) and Gallirallus australis australis (the South Island weka) from Nukuwaiata (Chetwode Islands), Pelorus Sound, New Zealand. A novel survey technique (entrance scores) was used in combination with a conventional technique (random searches for active weta) to measure changes in weta population parameters after the removal of predation pressure and to investigate impacts of exotic predators on tree weta. Tree weta density did not increase markedly over the 4‐year period, but the proportion of active adults did increase. Weta were observed to move into larger and more crowded galleries (refuges), to occupy galleries closer to the ground, and to spend less time sitting in gallery entrances. It was concluded that endemic tree weta are well adapted to withstand some introduced vertebrate predators but are able to live a more “relaxed” lifestyle in the absence of this predation. The most significant change detected was in weta age structure, with adults increasing their proportion of the population.     

The breeding biology of the gadfly petrels Pterodroma spp. of the Pitcairn Islands: characteristics, population sizes and controls

This paper reports the breeding biology and nesting seasons of the gadfly petrels which nest on the four islands of the Pitcairn group, Pitcairn, Henderson, Oeno and Ducie. The species currently breeding are Murphy's petrel Pterodroma ultima , Kermadec petrel P. neglecta , Herald petrel P. heraldica and Henderson petrel P. atrata. Of these, Murphy's petrel is the most numerous; an estimated 250000 pairs bred on Ducie, which is probably the major breeding station of the species. Novel basic breeding data for Murphy's petrel are presented. Incubation spells, averaging 19.3 days, are exceptionally long for a petrel. Phoenix petrel P. alba appears to have ceased to breed on the Pitcairn Islands since the 1922 surveys of the Whitney Expedition. Nesting success was low on Henderson Island during the study. For all four breeding species, less than 20% of eggs laid yielded fledglings. Failure occurred at the early chick stage and observations indicated that it was due to predation by Pacific rats Rattus exulans. Although rats are present on Ducie, predation was apparently less severe there. The situation on Oeno may be intermediate. I consider how the populations of Henderson are maintained in the face of this intense predation. The Murphy's petrel population may be sustained by immigration from Ducie while the Herald and Henderson petrel populations could be undergoing a long-term decline on Henderson. It is not clear how the Kermadec petrel population is maintained. The conservation implications of these findings are discussed.     

Rodents and their predators in the eastern Bay of Islands

Abstract

Traps were set for rodents and mustelids on five islands (Motukiekie, Moturua, Okahu, Urupukapuka, and Waewaetorea) in the eastern Bay of Islands in March 1984. Kiore (Rattus exulans) were caught on Moturua Island and Norway rats (R. norvegicus) on all five islands, but no mustelids were caught or seen. Kiore on Moturua Island were very scarce compared with other northern offshore islands, perhaps because of competition from Norway rats and the presence of stoats and cats. Kiore were breeding and young matured in the season of their birth. Norway rats were scarce and found mainly near the shoreline on four of the islands. On Waewaetorea Island they were plentiful and widespread despite the possible presence of stoats. About a third of the mature females were visibly pregnant. Average litter size was 6.9 embryos, and 44% of the parous females had borne two or three litters. Females first ovulated at 180 ± 5 g weight and 356 ± 5 mm total length on average. Males first produced sperm at 189 ± 7 g weight and 364 ± 4 mm total length. Most rats matured before reaching a tooth-wear age index of 5.     

Effects of alpha-chlorohydrin on the male reproductive tissues of the Polynesian rat,Rattus exulans

Abstract

Doses of α-chlorohydrin (‘Epibloc’) were administered by gavage to mature male Polynesian rats (Rattus exulans) at 100, 200, and 300 mg per kg body weight. Animals that survived were sacrificed either 1 day or 7 days later for assessment of epididymal and testicular cytology and sperm viability. Two of 10 animals died 6 days after treatment with 100 mg/kg; 1/6 died within 24 h of treatment with 200 mg/kg, though 6/10 died when left for 7 days; 300 mg/kg was lethal to all 3 rats tested. After 1 day, microscopic lesions were observed in the Initial Segment of the epididymis of 4/6 rats dosed with 100 mg/kg and in all 5 of the 200 mg/kg group; however, in only one animal at the higher dose level was the damage severe enough to cause epithelial exfoliation and potential blockage of the lumen. In all the animals that survived for 7 days testicular and epididymal cytology were normal, and viable spermatozoa were present at all levels of the tract. Autopsies revealed no evidence of gross epididymal lesions in any of the animals that died from the drug. We conclude that although α-chlorohydrin causes minor lesions in the epididymis of this feral species, the damage appears to be reversible in animals that survive an acute dose, and the drug cannot be considered an effective chemosterilant, as distinct from a poison.     

Some aspects of the biology of the hedgehog (Erinaceus europaeus L.) in the Manawatu,New Zealand

In a study area of 16.3 ha of dairy pasture and pine plantations in the Manawatu region of the southern North Island, 150 hedgehogs were marked and 356 recaptures recorded between 1 January 1970 and 24 June 1971. Population density was estimated at between 1.1/ha in winter and 2.5/ha in summer and autumn. Only 11 females and 5 males were considered to be residents, and these used overlapping feeding ranges of similar extent. Concentrations of food organisms became foci of hedgehog activity. During winter, when an estimated 20% of the population died, movement was restricted to the vicinity of the nest site; the hedgehogs hibernated fitfully during July‐October. The breeding season as such extended at least from November to March; some breeding activity was observed in most months, however. The average life span of adults was 1.97 years. The causes of 6 natural deaths and the incidence of abscesses and external parasites were noted.     

The foraging of New Zealand honeyeaters

Abstract

New Zealand has three species of honeyeaters, all of which feed on nectar, fruit, and ‘insects’. There is disagreement between published data and those becoming available from long-term studies on the relative proportion of these items in the diet. The effect of factors such as body size, dominance status, degree of movement, and time of year on diet and foraging behaviour are outlined, and predictions of differences between species and between sexes are made. A brief comparison of foraging in relation to the flora is made between New Zealand and Australian species.     

Panbiogeography and conservation science in New Zealand

Abstract

New Zealand’s official conservation science framework, the Protected Natural Areas Programme (PNA), is evaluated in relation to current biogeographic/systematic methods and principles with reference to philosophy, taxonomy, information content, and historical geological/biological relations. The PNA Programme and its parent International Union for Conservation of Nature and Natural Resources (IUCN) framework is based on a phenetic system of classification that does not reflect process (phylogenetic) characters of ecological systems. The PNA philosophy of conservation science is shown to be essentialist, rooted in traditional medieval Western metaphysics, and out of step with current developments in biogeography, systematics, and ecology. Panbiogeography is an appropriate global perspective for developing a conservation science because it meets the requirements of homology, monophyly, increased information content, and empirical testability whereas the PNA programme does not. Establishment of a Panbiogeographic Track Atlas is proposed as a suitable conservation framework for historical ecology and biogeography. The atlas could provide an empirical natural resource inventory to identify priority areas for conservation at an economically acceptable cost compared to the PNA Programme. Application of cladistic techniques to ecological and biogeographic patterns in relation to the Atlas can provide aphylogenetically sound hierarchical classification for conservation science. The potential benefits of the panbiogeographic approach for conservation education and tourism are discussed.     

Thermophilic anaerobic spirochetes in New Zealand hot springs

Abstract Electron and light microscopy revealed the presence of spirochetes in New Zealand thermal springs. The spirochete population in one spring studied (Kuirau Lake) was affected by fluctuations in temperature and/or pool level. A pure culture of the strictly anaerobic bacterium revealed that it grew optimally at a temperature of 45–50°C, with no growth occurring above 60°C, and a pH of 7.0–7.5 with no growth occurring at pH 5.5 or 8.5. Growth was inhibited by chloramphenicol, penicillin, streptomycin, tetracycline and neomycin but not by d -cycloserine, novobiocin or phosphomycin at 10 μg/ml. A wide range of carbohydrates were utilized but not organic acids. Acetate was the major end product of glucose fermentation with substantial amounts of ethanol and traces of lactate being produced.     

The Biocultural Context of Very High Fertility among the Bekaa Bedouin

This research report explores some of the biocultural dimensions of maximum or near maximum fertility among Bedouin tribes in the Bekaa Valley, Lebanon. The Bedouin case substantiates that very high fertility (completed family size [CFS] greater than 8.0) is found among peripheral peoples in frontier situations generated by major political-economic shifts. While the Bedouin maintained high fertility (CFS > 6.5) for approximately sixty years (1899–1960), very high fertility—linked to greater historical reliance on agriculture—was of shorter duration (1934–60). Comparisons with other very high fertility populations indicate that, at the proximate level, maximum fertility is associated with early weaning, low rates of primary sterility, and high rates of marital stability. Results also point to low subadult mortality in Bedouin society. Low mortality is best attributed to the availability of modern medical care facilities and high-quality weaning foods.