bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grasshopper biodiversity and bioindicators in Australian tropical savannas: Responses to disturbance in Kakadu National Park
Authors: Andersen Alan N. , Ludwig J. A. , Lowe Lyn M. , Rentz D. C. F. 
Published: March 2003

AbstractGrasshoppers are a dominant group of herbivorous insects throughout the world, and their high diversity, functional importance, sensitivity to disturbance and ease of sampling makes them potentially useful bioindicators for land management. In Australia, however, the dynamics of grasshopper assemblages are extremely poorly understood. Here we describe the responses of grasshopper (Acridoidea, Eumastacoidea and Tettigonioidea) assemblages in the Kakadu region of the Northern Territory, Australia to disturbance associated with mining. Three questions were addressed in this study: (i) do local grasshopper assemblages show consistent responses to disturbance?; (ii) can particular species or functional groups be identified that are reliable indicators of ecological disturbance?; and (iii) to what extent do the responses of grasshopper assemblages merely reflect those of vegetation? Grasshoppers were sampled at 26 sites located in and around the Ranger uranium mine, representing three habitat types with respect to degree of disturbance: (i) ‘natural’ (10 sites representing a range of ‘undisturbed’ savanna habitats); (ii) ‘disturbed’ (10 sites representing a range of disturbances, but with soil intact); and (iii) ‘waste rock’ (six sites undergoing rehabilitation on a constructed landform). A total of 56 grasshopper species in 46 genera was recorded during the study, with site species richness ranging from five to 20. There were no significant differences between habitat types in site species diversity, but multivariate analysis demonstrated a strong correspondence between grasshopper species composition and degree of habitat disturbance. Using Indicator Species Analysis, six species and one functional group were identified as significant indicators of habitat type in relation to disturbance. Grasshopper responses were correlated with that of vegetation, but grasshopper assemblages showed apparently meaningful differentiation among disturbed sites that was not evident on the basis of floristic data. Our results demonstrate that grasshopper assemblages respond to disturbances associated with human land use and that these responses do not simply reflect those of plants. Grasshoppers are therefore potentially useful bioindicators of ecological disturbance in Australia, but further work is required on the extent to which their responses reflect general ecological change.
Mate selection in Litoria chloris and Litoria xanthomera: Females prefer smaller males
Authors: Morrison Clare , Hero Jean‐Marc , Smith William P. 
Published: March 2003

AbstractIt is generally accepted that high quality males are those that succeed in male–male competition: in either aggression or rivalry to attract and be selected by females. Previous studies of amphibians have suggested that the main characters influencing male mating success include variation in call characteristics (e.g. call rate, call intensity), calling behaviour, body condition, age and chorus tenure. In the present paper, several of the characters influencing female mate choice (male body size, body condition, call rate, call frequency and chorus tenure) are investigated in two closely related, explosive breeding frog species Litoria chloris and Litoria xanthomera. Smaller males of both species are shown to be more successful than larger males and this success is attributed to the increased chorus tenure of smaller males in L. xanthomera. This increased chorus tenure was attributed to the lower total energy used per call by a small male calling at a higher frequency. Whether increased chorus tenure explains female mate choice in L. chloris is uncertain but is highly probable given the strong similarity between the two species in both ecology and call characteristics.
Opinion Practical and ethical considerations for students conducting ecological research involving wildlife
Authors: Monamy Vaughan , Gott Miranda 
Published: March 2003

AbstractThis commentary outlines relevant changes to the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes for ecologists and students active in field‐based wildlife research. All field‐based activities that require the approval of an Animal Ethics Committee (AEC) have now been detailed within the revised Code of Practice. Researchers and their students are required to give explicit consideration to the humane principles of replacement, reduction and refinement within their experimental protocols as a part of the AEC permission procedure. University‐based researchers also have obligations to train graduate students in the ethical as well as the practical components of wildlife research. In promoting this educational aim, a summary of ethical considerations in wildlife research is offered as a basis for discussion: the regulatory framework of research animal welfare (including an introduction to the Code of Practice, the AEC process and some thoughts on experimental design); and the humane principles on which the Code of Practice is based. Some practical considerations for field work relevant to students’ research training are also described.
Seed hoarding by rodents of the Monte Desert, Argentina
Authors: Giannoni Stella M. , Dacar Mariana , Taraborelli Paula , Borghi Carlos E. 
Published: March 2003

AbstractFood storage is an important adaptation of several animal species to the temporally variable or unpredictable food supplies that are typical of desert environments. In the present study, whether Eligmodontia typus and Graomys griseoflavus inhabiting sand dunes in the Monte desert displayed scatter‐hoarding was investigated. Both rodent species prepared surface caches by digging small holes (1–3 cm deep) in the soil. Caches were partially covered with sand and dry leaves, which meant that all of the cache sites at each station could be found. Most caches were found below shrubs, that is, in a sheltered microhabitat rather than near the food source. The mean distance between caches and seed sources was significantly higher than the mean distance from food sources to shrubs. The proportion of caches was significantly higher in shrubs with high safety cover. The adaptive significance of this foraging behaviour could be a competitive tactic for the rapid sequestering of food from a rich and ephemeral source. Such behaviour would reflect predation risk, which constitutes an important foraging cost in deserts, and could also influence plant community dynamics.
Changes in wolf spider (Araneae) assemblages across woodland–pasture boundaries in the central wheat‐belt of New South Wales, Australia
Authors: Martin Timothy J. , Major Richard E. 
Published: March 2003

AbstractThe abundance of wolf spiders (Lycosidae) was measured across woodland–pasture boundaries in the wheat‐belt of New South Wales, Australia, to determine the nature and magnitude of any edge effect. Spiders were collected by spotlighting along sample plots in woodlands located at distances of 5, 20, 35 and 200 m from the edge, and along sample plots in paddocks located at distances of 5 and 20 m from the edge. The wolf spider assemblage changed significantly across the edge, but the difference could be accounted for only by a change between the woodland and the paddock and not by any changes within the woodland at different distances from the edge. Ground cover (wolf spider microhabitat) changed significantly between the paddock and the woodland, but there were no consistent differences in microhabitat with distance from edge within either paddocks or woodlands. There was a significant correlation between an ordination of sites based on spider species abundance and an ordination based on microhabitat variables, suggesting that the wolf spider assemblage was responding to differences in microhabitat. Fine‐scale selection of microhabitat by most wolf spider species was non‐random, with most species preferring locations with grass cover, rather than more open locations. The present study indicates that wolf spiders are mostly unaffected by edge conditions at the woodland–paddock boundary. Accordingly, small and/or linear remnants with high edge‐to‐area ratios may constitute suitable faunal habitat for wolf spiders and perhaps other terrestrial arthropod species, despite the fact that this configuration is unsuitable for many vertebrate species.
Density, home range, seasonal movements and habitat use of the mountain pygmy‐possumBurramys parvus(Marsupialia: Burramyidae) at Mount Blue Cow, Kosciuszko National Park
Authors: Broome Linda S. 
Published: March 2003

AbstractA population of mountain pygmy‐possumsBurramys parvuswas studied at the Mount Blue Cow ski resort in Kosciuszko National Park between 1986 and 1989. Forty‐eight individuals were radiotracked during the snow‐free months and 21 individuals were tracked during winter over the 3 years of study. Trapping and radiotracking showed that the density, population structure, movements and home range sizes ofB. parvuson Mount Blue Cow were strongly correlated with elevation and changed with the season. Female densities were greatest in habitats characterized by deep boulderfields, at high elevations with an abundance of Bogong moths. Males visited the areas where females were located to breed in November–December and then by February, the majority migrated to lower elevations or north and westerly aspects. Females that nested at lower elevations also visited high‐elevation habitats to access the high concentrations of Bogong moths, which were the main food source in summer. A high proportion of the juvenile males and some juvenile females dispersed to lower elevations in March and April. The resulting sexual segregation during autumn and winter may be a result of female aggression or scramble competition, but is also explainable by differences in energy requirements, seed availability and hibernation strategies between the sexes. The extraordinarily large nightly and seasonal movements between habitat patches of up to 2 km for females and 3 km for males, sexual segregation and the use of different hibernation sites have important implications for the management of this species. These include the need for movement and dispersal corridors and the conservation of boulder‐heath habitats outside the main boulderfields.
Assessing the disturbance impact on vegetation and lizard communities of fluoride pollution interacting with fire and mining in eastern Australia
Authors: Taylor Jennifer E. , Fox Barry J. 
Published: March 2003

AbstractThe effects of atmospheric fluoride pollution on the lizard fauna of the open forest of coastal dunes in New South Wales, Australia were examined. Lizards were pitfall‐trapped at sites with background fluoride levels (< 0.25 μmol F.g–1), or subject to low (1.85–3.4 μmol F.g–1) or high (8.00–13.2 μmol F.g–1) levels of fluoride pollution. Sites had been disturbed by fire or mineral sand‐mining 4 or 8 years prior to the study. Fluoride pollution resulted in significant changes to canopy cover, understorey vegetation density and ground cover. Where fluoride levels were low in unmined forest, there was significantly higher species richness, total lizard abundance and abundance of the most common species, Lampropholis guichenoti and Lampropholis delicata (Scincidae), compared with areas of high or background fluoride levels. Both the present and previous studies show that fluoride pollution is significantly correlated with increased abundance of the most common lizard species in sand‐mined areas, Ctenotus robustus, Ctenotus taeniolatus (Scincidae) and Amphibolurus muricatus (Agamidae). A discriminant function model of background‐fluoride mined sites was used to predict lizard abundances based on vegetation density, leaf litter density and soil hardness. The model was verified by using it to predict similarities between background‐fluoride sites and fluoride‐affected sites. The sites within each predicted group were more similar in lizard species composition than when grouping of sites was done by time since mining or fire. With this analysis, a close relationship between vegetation variables and the lizard fauna, irrespective of the type of disturbance or time since disturbance, is demonstrated. Discriminant function analysis suggested that Ctenotus would be unlikely to use unmined forest sites that had been burned within 12 months previously. Thus it seems unlikely that the original open forest of these coastal dunes would have supported populations of either C. robustus or C. taeniolatus. In conclusion, the original source of Ctenotus that colonized sand‐mined areas is more likely to have been the relatively small areas of heath vegetation in the area. Therefore, sand‐mining and atmospheric fluoride pollution result in landscape‐scale changes to the relative abundance of lizard species, with forest species becoming less common and lizard species from open areas becoming more common.
Seed supply as a limiting factor for granivorous bird assemblages in the Monte Desert, Argentina
Authors: Blendinger Pedro G. , Ojeda Ricardo A. 
Published: March 2003

AbstractSeed availability may limit the size of granivorous bird populations, particularly in desert environments. Seasonal and annual fluctuations in the abundance of granivorous birds were studied at three sites in the Northern Monte Desert, Argentina. The way in which these changes were related to seed supply was also studied. Granivore abundance and biomass, as well as seed abundance, were greater in winter. Changes in total granivore abundance were mostly because of variations in numbers of the most mobile bird species, all of which were found to have similar patterns of variation in their abundance. Evidence suggests that during the non‐breeding season, the most mobile species are able to track patches of high seed availability over long distances, whereas the abundance of less vagile species largely depends on the local ecological conditions. Seed supply is a proximate factor that limits the abundance of granivorous birds in the Monte Desert during the winter, but does not limit species richness. Granivore abundance was not correlated with seed supply in spring.
Nutrient accessions in a mixed conifer–angiosperm forest in northern New Zealand
Authors: Enright N. J. 
Published: March 2003

AbstractNutrient accessions in litterfall are described for a mixed conifer (mostly Agathis australis D.Don (Lindl.), New Zealand kauri) and angiosperm temperate forest in northern New Zealand to determine the relative contributions to nutrient cycling of the conifer and angiosperm components of the forest. Concentrations for many nutrients were significantly lower in conifer litterfall fractions than for equivalent angiosperm fractions. Angiosperm leaves had concentrations of N and P twice those found in conifer leaf fall. Despite a large contribution to litterfall from weight, conifer reproductive parts (mostly cone scales) were very low in nutrients (especially N, P and Ca). Whereas angiosperm litterfall constituted < 45% of total litterfall by weight, nutrient accessions from the angiosperm component accounted for 45–60% of total nutrient accessions and the conifer fraction for only 30–45%, almost the exact reverse of their contributions to litterfall by weight. Of the macronutrients, P (3 kg ha–1 year–1) showed the lowest rate of accession in litterfall while Ca (84 kg ha–1 year–1) showed the highest. Faunal detritus, although < 1% of total litterfall by weight, contributed 10% of total P and 4% of total N reaching the forest floor via the litterfall pathway each year. The C:N and C:P ratios in litterfall and litterstore were all well above the levels at which mineralization is likely to occur. Based on the estimated residence times, long‐term immobilization was more likely for N than for P. The annual pattern of nutrient accessions differed for the two components, with angiosperm accessions highest in spring and summer, and conifer accessions highest in autumn, due largely to a peak in litterfall of reproductive parts at that time of year. It is argued that differences in litter quality, decomposition rates and spatial and temporal patterns of litterfall for angiosperm versus conifer components of the forest, in conjunction with long‐term disturbance regimes, may contribute to conifer–angiosperm coexistence.
Insect damage in Eucalyptus: A review of plantations in Chile
Authors: Lanfranco D. , Dungey H. S. 
Published: March 2003

AbstractChile has more than 330 000 ha of eucalypt plantations, predominantly in the eighth to the tenth region (approximately 34 to 41°S). Eucalyptus globulus ssp. globulus is the principal eucalypt planted, but Eucalyptus nitens, Eucalyptus camaldulensis, Eucalyptus delegatensis and Eucalyptus viminalis are also grown. There are four main insect pests that have been detected attacking these eucalypts in Chile: the defoliator Gonipterus scutellatus, the bark borers Phoracantha semipunctata and Phoracantha recurva and the native wood borer Chilecomadia valdiviana. More recently, Thyrinteina arnobia and Ctenarytaina eucalypti have been detected. Gonipterus scutellatus and P. recurva have been discovered in Chile within the last 2 years and it is hoped they may still be eliminated using a combination of biological control and chemical control of local populations. Phoracantha recurva and P. semipunctata are not considered a problem because attack only occurs in areas of water deficit, away from current eucalypt plantations. Chilecomadia valdiviana can damage plantations of E. nitens but rarely attacks other eucalypts.◊Chilecomadia valdiviana may cause future problems through further host shifts. Thyrinteina arnobia has only been detected during quarantine surveillance in the port of Valparaiso. Ctenarytaina eucalypti, recently detected in August 1999, had an initial limited distribution in the first region. However, since then, this insect has expanded its distribution south up to the tenth region. None of the insects recorded on eucalypts in Chile to date currently presents a threat to the eucalypt industry. It is also essential that additional resources are made available for their continued monitoring and control, particularly given that the 44% of plantations are held by small to medium property owners that would otherwise be unable to control a serious outbreak because of economic restrictions.
Insect herbivory and ontogeny: How do growth and development influence feeding behaviour, morphology and host use?
Authors: Hochuli Dieter F. 
Published: March 2003

AbstractHerbivorous insects exploit many different plants and plant parts and often adopt different feeding strategies throughout their life cycle. The conceptual framework for investigating insect–plant interactions relies heavily on explanations invoking plant chemistry, neglecting a suite of competing and interacting pressures that may also limit herbivory. In the present paper, the methods by which ontogeny, feeding strategies and morphological characters inhibit herbivory by mandibulate holometabolous insects are examined. The emphasis on mechanical disruption of plant cells in the insect digestive strategy changes the relative importance of plant ‘defences’, increasing the importance of leaf structure in inhibiting herbivory. Coupled with the implications of substantial morphological and behavioural changes in ontogeny, herbivores adopt a range of approaches to herbivory that are independent of plant chemistry alone. Many insect herbivores exhibit substantial ontogenetic character displacement in mandibular morphology. This is tightly correlated with changes in feeding strategy, with changes to the cutting edges of mandibles increasing the efficiency of feeding. The changes in feeding strategy are also characterized by changes in feeding behaviour, with many larvae feeding gregariously in early instars. Non‐nutritive hypotheses considering the importance of natural enemies, shelter‐building and thermoregulation may also be invoked to explain the ontogenetic consequences of changes to feeding behaviour. There is a need to integrate these factors into a framework considering the gamut of potential explanations of insect herbivory, recognizing that ontogenetic constraints are not only viable explanations but a logical starting point. The interrelations between ontogeny, size, morphology and behaviour highlight the complexity of insect–plant relationships. Given the many methods used by insect herbivores to overcome the challenges of consuming foliage, the need for species‐specific and stage‐ specific research investigating ontogeny and host use by insect herbivores is critical for developing general theories of insect–plant interactions.
Pollination and fruit‐set of Grevillea robusta in western Kenya
Authors: Kalinganire A. , Harwood C. E. , Slee M. U. , Simons A. J. 
Published: March 2003

AbstractThe floral visitors of silky oak, Grevillea robusta A. Cunn. ex R.Br., their foraging behaviour and their effects on fruit‐set were studied at Malava, western Kenya. Grevillea robusta is a popular tree for farm plantings in the eastern and central African highlands. Yield of seed has been disappointingly low in some areas and a lack of appropriate pollinators has been suggested as a possible cause. Investigations involved the monitoring of visitors on active inflorescences, assessment of the rewards available to potential pollinators, and exclusion experiments to establish the effects of various visitors on fruit‐set. The flowers are visited mainly by birds and insects. The likely pollinators of G. robusta are sunbirds (Nectarinia amethystina, N. cyanolaema, N. olivacea, N. superba and N. venusta) and white‐eyes (Zosterops kikuyuensis and Z. senegalensis). Very little aggressive behaviour between birds was recorded. No nocturnal pollinators were observed. Nectar was the major floral reward for pollinators, but is likely depleted by ants and honey bees, the foraging behaviour of which confirmed them to be nectar‐robbers. These insects hardly ever touched stigmas during their visits. Eighty‐nine per cent of bird visits were in the morning (07.00–10.00 hours) when nectar volume was highest. Inflorescences bagged to exclude birds set no fruits, and unmanipulated flowers and flowers bagged with self‐pollen set no fruits, indicating a self‐incompatibility mechanism. Control cross‐pollinated flowers displayed greatly increased fruit‐set (25.1%) compared with natural open‐pollination (0.9%). All these findings confirm the importance of cross‐pollen transfer to flowers and the necessity of pollinators for fruit‐set. Effective seed production requires activity of pollinators for self‐pollen removal and cross‐pollen deposition. Seed production stands for G. robusta should be established where flowering is prolific and bird pollinators are abundant.
Colonization of eucalypts in New Zealand by Australian insects
Authors: Withers T. M. 
Published: March 2003

AbstractSince the 1860s, Australian insects have steadily colonized eucalypts in New Zealand. The rate of colonization has increased markedly over the last two decades. This increase may be related to increasing trade between the two countries. Currently there are 26 specialist eucalypt insect species and approximately 31 polyphagous insect species that can feed on Eucalyptus in New Zealand. The specialist eucalypt insects endemic to Australia have generally caused more damage than polyphagous or native insects. Eucalypt‐specific insects are dominated by sap sucking bugs, particularly psyllids, and defoliating Coleoptera and Lepidoptera. In some cases the major insect pest species have been those that are only occasional pests in Australia, for example Gonipterus scutellatus, Ctenarytaina eucalypti, Eriococcus coriaceus and Phylacteophaga froggatti. Some important insect pests have been rare, or even not described from Australia, prior to their appearance as a pest in New Zealand, for example Paropsis charybdis and Ophelimus eucalypti. Invading eucalypt insects are more likely to establish in the Auckland region than anywhere else in New Zealand.