1,720,965 research outputs found
Ecological implications of habitat fragmentation and restoration for the gecko Hoplodactylus maculatus
No full textHabitat modification has created heterogeneous landscapes that either restrict animals to remnants of suitable habitat or challenges them to use live created matrices. To successfully predict effects of landscape change, such as habitat fragmentation and reforestation, it is important to understand the habitat choice and movement patterns of representative taxa. New Zealand geckos are functionally important parts of endemic ecosystems; however, much is unknown about their ecology and population biology. Furthermore, sampling difficulties have restricted their study. Here I compare the efficiency and reliability of common sampling methods for the New Zealand common gecko, Hoplodactylus maculatus, and determine its habitat choice in three vegetation types (grassland, young replanted forest, older remnant forest) on Mana Island and Stephens Island in Cook Strait, New Zealand. I then investigate gecko distributions in relation to habitat edges. Artificial cover objects (ACOs) prove to be a useful method to survey and monitor gecko populations, especially in younger forests. Hoplodactylus maculatus is abundant in young and older forests, however, mostly absent from grassland. Demographic proportions differ between sites, in that juveniles are more abundant in earlier successional vegetation than in remnant patches. Body condition is overall lower in replanted native vegetation and in grassland than in remnant forest, while more individuals are affected by external parasitism by mites (Neotrombicula spp.) in remnant forests. Geckos are predominantly found above ground in forest patches, and particularly at the edges. Demographic patterns differ between habitats. Adult geckos are found at similar abundances throughout forest patches while juveniles are most common at habitat patch edges. Significantly fewer geckos of all age classes were found in the grassland than in either of the forest habitats. Of the few geckos that were found in grassland, the majority were juveniles. This may imply density dependent natal dispersal into suboptimal habitat. This research shows that ACOs are a useful method for sampling Hoplodactylus maculatus. Gecko demographics and body condition are not randomly distributed and specific habitat preferences were identified. Geckos are mostly absent from grasslands and, as natal dispersal is directed towards habitat edges into this matrix, habitat fragmentation is predicted to affect this taxon negatively. Restoration of native forest will positively influence abundance of Hoplodactylus maculatus, while connectivity of native vegetation will aid dispersal and distribution
Foraging Interference and Fruit Palatability in Pteropus Scapulatus (Megachiroptera: Pteropodidae): Management Implications
No full textThe “residents and raiders” theory emphasizes the importance of conspecific feeding interference in seed dispersal by frugivorous megachiropterans. Agonistic interactions at fruiting trees frequently result in the “ejection” of one bat, which has often first obtained some fruit. The ejected bat then flies to an unoccupied tree, thus dispersing non-consumed seeds. For seeds too large to be swallowed this may be the sole method of dispersal. Raiding and subsequent seed spread only occur when bat populations are sufficiently large, relative to resources, to cause competition for food. If competition similarly affects nectarivorous bats and their floral resources, decline in a bat population could lead to reduced seed set and genetic diversity in their food-plant species. Pteropus scapulatus (Little Red Flying Fox) visit the flowers of dozens of Australian and New Guinean species and are believed to play an important role in the pollination of Eucalyptus and Melaleuca. Feeding-interference and raiding “success” by P. scapulatus eating fruit at Wellington Zoo (New Zealand) was studied to infer the importance of population size on cross-pollination. Decrease in population-to-resource ratio was correlated with decrease in raiding frequency, suggesting a decreased likelihood of cross pollination. These results highlight the value of management practices that promote the maintenance of large populations of nectarivorous megachiropterans. The effects of dominance and food preference on these behaviours were also evaluated. Dominance was inversely correlated to both dispersal and maturity. Contrary to many reports, females were not always subordinate to males. Fruit preference data may be useful for selecting “distracter” trees in orchards prone to damage by fruit bats and for ex situ husbandry concerns. Implications for population-, orchard-, and captive-management are discussed
Circadian and ontogenetic changes in activity and anti-predator responses of captive juvenile tuatara (Sphenodon spp.)
No full textBehaviour is a fundamental part of the ecology of any animal and is important for its survival and subsequent fitness. Knowledge of the behaviour of rare species can help scientists understand their population dynamics and persistence. This knowledge may then be applied to management procedures. In the wild, behavioural traits evolve in response to specific selection pressures, such as competition for resources, predation, and thermal requirements. However, in captivity selection pressures are relaxed, resulting in changes in behaviour, which may affect the survival of captive-reared individuals upon release into the wild. Tuatara (Sphenodon spp.) are rare reptiles, endemic to New Zealand. Head-starting is used as a tool for the conservation of tuatara, yet the effects of captive-rearing on the behaviour and subsequent post-release survival of tuatara are not known. I investigated circadian changes in emergence, activity, territoriality, and anti-predator responses in two- and three-year old S. guntheri and five-year old S. punctatus. I also re-analysed anti-predator response data available from another study on the same S. punctatus, tested at one, six, and 10 months of age.
Juvenile tuatara emerge predominantly at night, but are most active, that is, move around above ground, mainly during the day and around sunset. The level of territoriality was consistently high throughout the 24 h period, potentially due to its importance in resource acquisition. Juvenile tuatara were significantly more likely to flee from predator models than to freeze. The likelihood of fleeing was higher during day. A decrease in flight tendency was observed during the first 10 months of age, but increased from the age of 10 months to five years in S. punctatus, possibly as a result of the intense monitoring regime during the first 10 months.
Nocturnal emergence and crepuscular activity may be driven by the high abundance of resources (e.g., insects) after sunset and the lower likelihood of detection by visually-hunting predators. However, low nocturnal temperatures restrict locomotor ability, limiting movements and active anti-predator responses (i.e. flight) to day-time. Handling may affect behavioural responses of captive tuatara to predators. Anti-predator behaviour has consequences for the survival of released individuals and establishment of new populations founded on captive-reared animals. 1 recommend handling is kept to a minimum throughout head-starting. I also advise that a quantitative study on post-release tuatara is conducted to establish whether the survival of individuals is correlated with flight responses to predator models in captivity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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