scholarly journals The impacts of an introduced mammalian predator (Mus musculus) on tree weta (Hemideina trewicki) and skinks (Oligosoma polychroma, Oligosoma infrapunctatum and Oligosoma lineoocellatum) in Cape Sanctuary, Hawkes Bay

2021 ◽  
Author(s):  
◽  
Emma Dent
Keyword(s):  
Native Species ◽  
Conservation Management ◽  
Limiting Factor ◽  
Pitfall Traps ◽  
Mark Recapture ◽  
Introduced Predators ◽  
Native Populations ◽  
Mammalian Predator ◽  
Tree Weta ◽  
The Impact

<p>The introduction of exotic species, particularly predators, into new ecosystems is one of the biggest causes of loss of biodiversity across the globe. Understanding the impacts that introduced species have on native species is crucial in conservation management, particularly for those species that are conservation-reliant. I examined the impact that an introduced mammalian predator (Mus muscularus) had on native prey populations of common (Oligosoma polychroma), speckled (Oligosoma infrapunctatum) and spotted (Oligosoma lineoocellatum) skinks and Hawkes Bay tree weta (Hemideina trewicki). I conducted a mark-recapture study using pitfall traps to examine the impact of mice on skink populations. I conducted a mark-recapture study through manual counts to examine the impact of mice on tree weta. I also examined occupancy of weta refuges while in the presence of mice. There were no captures of spotted skinks, and very low captures of common skinks. There was no significant change in capture numbers for speckled skink, however observed numbers did decline from November 2013 to November 2014. There was a significant decline in capture rates for tree weta over the course of my study. It was difficult to establish mice as the sole cause of any observed changes, however it is likely that they are a limiting factor for skink and weta populations, and have the potential to be a major factor in the observed decline in the tree weta population. My results highlight the importance of monitoring native populations, particularly those that are small and are in the presence of introduced predators. By monitoring native populations conservation management can make better informed decisions to work towards populations not being ‘conservation-reliant’.</p>

scholarly journals The impacts of an introduced mammalian predator (Mus musculus) on tree weta (Hemideina trewicki) and skinks (Oligosoma polychroma, Oligosoma infrapunctatum and Oligosoma lineoocellatum) in Cape Sanctuary, Hawkes Bay

2021 ◽  
Author(s):  
◽  
Emma Dent
Keyword(s):  
Native Species ◽  
Conservation Management ◽  
Limiting Factor ◽  
Pitfall Traps ◽  
Mark Recapture ◽  
Introduced Predators ◽  
Native Populations ◽  
Mammalian Predator ◽  
Tree Weta ◽  
The Impact

<p>The introduction of exotic species, particularly predators, into new ecosystems is one of the biggest causes of loss of biodiversity across the globe. Understanding the impacts that introduced species have on native species is crucial in conservation management, particularly for those species that are conservation-reliant. I examined the impact that an introduced mammalian predator (Mus muscularus) had on native prey populations of common (Oligosoma polychroma), speckled (Oligosoma infrapunctatum) and spotted (Oligosoma lineoocellatum) skinks and Hawkes Bay tree weta (Hemideina trewicki). I conducted a mark-recapture study using pitfall traps to examine the impact of mice on skink populations. I conducted a mark-recapture study through manual counts to examine the impact of mice on tree weta. I also examined occupancy of weta refuges while in the presence of mice. There were no captures of spotted skinks, and very low captures of common skinks. There was no significant change in capture numbers for speckled skink, however observed numbers did decline from November 2013 to November 2014. There was a significant decline in capture rates for tree weta over the course of my study. It was difficult to establish mice as the sole cause of any observed changes, however it is likely that they are a limiting factor for skink and weta populations, and have the potential to be a major factor in the observed decline in the tree weta population. My results highlight the importance of monitoring native populations, particularly those that are small and are in the presence of introduced predators. By monitoring native populations conservation management can make better informed decisions to work towards populations not being ‘conservation-reliant’.</p>

The effect of increased ground-level habitat complexity on mouse population dynamics

2003 ◽  
Vol 30 (6) ◽  
pp. 565 ◽  
Author(s):  
A. D. Arthur ◽  
R. P. Pech ◽  
A. Drew ◽  
E. Gifford ◽  
S. Henry ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Native Species ◽  
Habitat Complexity ◽  
Habitat Structure ◽  
Ground Level ◽  
Low Complexity ◽  
Mouse Population ◽  
Introduced Predators ◽  
The Impact

We investigated experimentally the influence of habitat structure on the population dynamics of house mice. Three habitat types were used. In one, dense stands of regenerating cypress pine were felled and left in situ to cover at least 40% of experimental plots, providing high complexity at ground level; in another, dense stands of regenerating pine were left intact, providing low complexity at ground level; in the third, open grassland adjacent to dense stands of regenerating pine also provided low complexity at ground level. Mouse populations occurred at higher densities in felled pine plots compared with both the standing pine and grassland plots, consistent with the hypothesis that the presence of increased habitat complexity at ground level reduced the impact of predation. Even though populations responded to the felled pine, they dropped to very low densities over winter, suggesting that the habitat was still marginal for the persistence of mice, probably due to a lack of food. The results are discussed with reference to their implications for the influence that habitat structure may have on the impact of introduced predators on native species.

Density estimates of cane toads from native populations based on mark-recapture data

1996 ◽  
Vol 23 (3) ◽  
pp. 305 ◽  
Author(s):  
M Lampo ◽  
P Bayliss
Keyword(s):  
Air Temperature ◽  
Native Species ◽  
Population Estimates ◽  
Cane Toad ◽  
Potential Threat ◽  
Density Estimates ◽  
Mark Recapture ◽  
Climate Conditions ◽  
Wide Range ◽  
Native Populations

The cane toad (Bufo marinus) has received considerable attention because of its rapid spread in Australia and the potential threat it may represent to native species. Although the introduction of pathogens from native populations is now being considered to control this species, population estimates based on comparable methods that demonstrate that native populations are in fact less dense than the introduced ones are not available. Accurate population estimates are necessary to evaluate potential techniques for the control of the cane toad. We estimated population densities of cane toads over a wide range of habitat types and climate conditions by means of mark-recapture data. The capture history and location of toads each night were analysed to explore the validity of some of the assumptions of mark-recapture models. Because migrations, deaths and recruitment over three nights appear to be unimportant, populations may be legitimately regarded as closed for that period. However, cane toads seem highly sensitive to disturbance effects due to trapping andlor handling. Consequently, density estimates based on removal methods seem the most reliable because they are not sensitive to handling and trapping effects. Similarly, analyses of residuals of regressions between 1-night counts and density estimates suggested that toad nightly activity is affected by the air temperature during sampling. However, only 60% of the variation in estimated densities can be predicted by 1-night counts and air temperature. Estimates of population density over a wide range of habitats in South America were one order of magnitude lower than estimates in Australia. We speculate on the possible factors that may account for the lower densities in populations in the native range of the species.

The impact of mammalian insectivores Rattus rattus (Rat), Mus musculus (Mouse) & Erinaceus europeus (Hedgehog) on the size and abundance of mainland Coleoptera and Orthoptera

2021 ◽  
Author(s):  
◽  
Thomas Hewitt
Keyword(s):  
Mus Musculus ◽  
Rattus Rattus ◽  
Temporal Analysis ◽  
Invertebrate Communities ◽  
Introduced Predators ◽  
Mammalian Predators ◽  
Study Sites ◽  
Tree Weta ◽  
Occupancy Rates ◽  
The Impact

<p>The impact of introduced mammalian predators on indigenous vertebrates is relatively well documented, however the general responses of indigenous invertebrate communities is less well known. Many indigenous invertebrates, particularly the large flightless species such as those in the genus Deinacrida (Orthoptera) and Anagotus (Curculionidae) have been extirpated from much of their range due largely to the impacts of introduced predators. Despite these well-known examples very little is known about the general impact of introduced predators on invertebrate communities. Beginning in 2012 pitfall traps and artificial wētā motels were established across seven study sites in the Aorangi and Remutaka ranges east of Wellington alternately baited with squid and monitored two to three times annually. Mammal tracking took place in the form of tracking tunnels giving three mammal indexes for rats (Rattus rattus), mice (Mus musculus) and hedgehogs (Erinaceus europeus). Cavity dwelling wētā in wētā motels were measured and counted in situ whilst pitfall trapped Coleoptera and Orthoptera were transported to the lab for measuring and identification. Linear mixed effects model, type 3 ANOVAS and generalised linear mixed models were used to examine whether mammal index had any impact on the size and the catch or occupancy of invertebrates. Increased rat and mouse tracking was associated with reduced coleoptera catch whilst increased hedgehog tracking was correlated with increases in Coleoptera catch. Pitfall trapped wētā (Hemiandrus spp) showed strong negative responses to increased rat tracking, neutral responses to mice and positive responses to hedgehogs. Tree wētā (Hemideina crassidens) occupancy rates declined in response to increased mouse abundance whilst the mean size of tree wētā residing in wētā motels showed an increase in response to rats and mice. These results show the complexity of understanding mammal invertebrate interactions which cannot be expected to be the same in all environments or across all taxa. Environmental factors typically impact far more strongly on invertebrate populations than they do on vertebrates and can obscure the impacts of top down predation in such studies. The results reported in this study only became apparent after 5+ years of sampling, demonstrating the importance of long-term temporal analysis of invertebrate communities in response to mammals before trends start to emerge. More research is required into the basic ecology and population dynamics of invertebrate communities before more general trends can be discerned.</p>

scholarly journals The impact of mammalian insectivores Rattus rattus (Rat), Mus musculus (Mouse) & Erinaceus europeus (Hedgehog) on the size and abundance of mainland Coleoptera and Orthoptera

2021 ◽  
Author(s):  
◽  
Thomas Hewitt
Keyword(s):  
Mus Musculus ◽  
Rattus Rattus ◽  
Temporal Analysis ◽  
Invertebrate Communities ◽  
Introduced Predators ◽  
Mammalian Predators ◽  
Study Sites ◽  
Tree Weta ◽  
Occupancy Rates ◽  
The Impact

<p>The impact of introduced mammalian predators on indigenous vertebrates is relatively well documented, however the general responses of indigenous invertebrate communities is less well known. Many indigenous invertebrates, particularly the large flightless species such as those in the genus Deinacrida (Orthoptera) and Anagotus (Curculionidae) have been extirpated from much of their range due largely to the impacts of introduced predators. Despite these well-known examples very little is known about the general impact of introduced predators on invertebrate communities. Beginning in 2012 pitfall traps and artificial wētā motels were established across seven study sites in the Aorangi and Remutaka ranges east of Wellington alternately baited with squid and monitored two to three times annually. Mammal tracking took place in the form of tracking tunnels giving three mammal indexes for rats (Rattus rattus), mice (Mus musculus) and hedgehogs (Erinaceus europeus). Cavity dwelling wētā in wētā motels were measured and counted in situ whilst pitfall trapped Coleoptera and Orthoptera were transported to the lab for measuring and identification. Linear mixed effects model, type 3 ANOVAS and generalised linear mixed models were used to examine whether mammal index had any impact on the size and the catch or occupancy of invertebrates. Increased rat and mouse tracking was associated with reduced coleoptera catch whilst increased hedgehog tracking was correlated with increases in Coleoptera catch. Pitfall trapped wētā (Hemiandrus spp) showed strong negative responses to increased rat tracking, neutral responses to mice and positive responses to hedgehogs. Tree wētā (Hemideina crassidens) occupancy rates declined in response to increased mouse abundance whilst the mean size of tree wētā residing in wētā motels showed an increase in response to rats and mice. These results show the complexity of understanding mammal invertebrate interactions which cannot be expected to be the same in all environments or across all taxa. Environmental factors typically impact far more strongly on invertebrate populations than they do on vertebrates and can obscure the impacts of top down predation in such studies. The results reported in this study only became apparent after 5+ years of sampling, demonstrating the importance of long-term temporal analysis of invertebrate communities in response to mammals before trends start to emerge. More research is required into the basic ecology and population dynamics of invertebrate communities before more general trends can be discerned.</p>

scholarly journals Long-term changes in the plant ecology of an African savanna landscape and the implications for ecosystem theory and conservation management

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
David Western ◽  
Victor N. Mose ◽  
David Maitumo ◽  
Caroline Mburu
Keyword(s):  
Human Impact ◽  
National Parks ◽  
Conservation Management ◽  
Plant Ecology ◽  
Ecological Resilience ◽  
Pasture Production ◽  
Ecosystem Theory ◽  
The Impact

Abstract Background Studies of the African savannas have used national parks to test ecological theories of natural ecosystems, including equilibrium, non-equilibrium, complex adaptive systems, and the role of top-down and bottom-up physical and biotic forces. Most such studies have excluded the impact of pastoralists in shaping grassland ecosystems and, over the last half century, the growing human impact on the world’s rangelands. The mounting human impact calls for selecting indicators and integrated monitoring methods able to track ecosystem changes and the role of natural and human agencies. Our study draws on five decades of monitoring the Amboseli landscape in southern Kenya to document the declining role of natural agencies in shaping plant ecology with rising human impact. Results We show that plant diversity and productivity have declined, biomass turnover has increased in response to a downsizing of mean plant size, and that ecological resilience has declined with the rising probability of extreme shortfalls in pasture production. The signature of rainfall and physical agencies in driving ecosystem properties has decreased sharply with growing human impact. We compare the Amboseli findings to the long-term studies of Kruger and Serengeti national parks to show that the human influence, whether by design or default, is increasingly shaping the ecology of savanna ecosystems. We look at the findings in the larger perspective of human impact on African grasslands and the world rangelands, in general, and discuss the implications for ecosystem theory and conservation policy and management. Conclusions The Amboseli study shows the value of using long-term integrated ecological monitoring to track the spatial and temporal changes in the species composition, structure, and function of rangeland ecosystems and the role of natural and human agencies in the process of change. The study echoes the widespread changes underway across African savannas and world’s rangelands, concluding that some level of ecosystem management is needed to prevent land degradation and the erosion of ecological function, services, and resilience. Despite the weak application of ecological theory to conservation management, a plant trait-based approach is shown to be useful in explaining the macroecological changes underway.

Galapagos Tortoises and Sea Turtles in Gold Rush-Era California

2014 ◽  
Vol 91 (2) ◽  
pp. 20-39 ◽  
Author(s):  
Cyler Conrad ◽  
Allen Pastron
Keyword(s):  
San Francisco ◽  
Native Species ◽  
Sea Turtles ◽  
Rare Event ◽  
Legal Protection ◽  
Sea Turtle ◽  
Gold Rush ◽  
Late Nineteenth Century ◽  
Scientific Curiosity ◽  
Native Populations

Spotting a sea turtle or Galapagos tortoise on the early wharfs and streets of San Francisco or Sacramento, California during the Gold Rush (1848-1855) would not have been a rare event. Massive population influx into the San Francisco Bay region during this time resulted in substantial impacts to native species and habitats of all taxa, but the demand for food resulted in many resources, turtles and tortoises included, being imported into the cities. Providing a fresh and delectable food source, these terrapin were brought to San Francisco and Sacramento to feed the hungry Gold Rush populous. Their taste, popularity and demand also resulted in small numbers being imported into gold mining towns in the San Joaquin Valley and foothills of the Sierra Nevada’s. Remarkable as this process was, the consumption and importation of both sea turtles and Galapagos tortoises during the Gold Rush pushed native populations of these species to the brink of extinction during the mid to late-nineteenth century. Declining numbers of terrapin and increased scientific curiosity, with a desire to safeguard these creatures for future generations, resulted in their eventually legal protection and conservation. In many ways the impacts of the decimation of terrapin in the eastern Pacific during the Gold Rush are still felt today, as conservation and breeding efforts continue in an attempt to return native turtle and tortoise populations to pre-Euro-American contact levels. This research describes the historical, and new archaeofaunal, evidence of the terrapin import market in San Francisco, Sacramento and beyond during the dynamic period of the California Gold Rush.

scholarly journals Diet composition of the invasive red-whiskered bulbul Pycnonotus jocosus in Mauritius

2010 ◽  
Vol 26 (3) ◽  
pp. 347-350 ◽  
Author(s):  
Jannie Fries Linnebjerg ◽  
Dennis M. Hansen ◽  
Nancy Bunbury ◽  
Jens M. Olesen
Keyword(s):  
Invasive Species ◽  
Introduced Species ◽  
Native Species ◽  
Diet Composition ◽  
Ecological Perspective ◽  
Positive Interactions ◽  
Invasional Meltdown ◽  
Ecological Processes ◽  
Successful Establishment ◽  
The Impact

Disruption of ecosystems is one of the biggest threats posed by invasive species (Mack et al. 2000). Thus, one of the most important challenges is to understand the impact of exotic species on native species and habitats (e.g. Jones 2008). The probability that entire ‘invasive communities’ will develop increases as more species establish in new areas (Bourgeois et al. 2005). For example, introduced species may act in concert, facilitating one another's invasion, and increasing the likelihood of successful establishment, spread and impact. Simberloff & Von Holle (1999) introduced the term ‘invasional meltdown’ for this process, which has received widespread attention since (e.g. O'Dowd 2003, Richardson et al. 2000, Simberloff 2006). Positive interactions among introduced species are relatively common, but few have been studied in detail (Traveset & Richardson 2006). Examples include introduced insects and birds that pollinate and disperse exotic plants, thereby facilitating the spread of these species into non-invaded habitats (Goulson 2003, Mandon-Dalger et al. 2004, Simberloff & Von Holle 1999). From a more general ecological perspective, the study of interactions involving introduced and invasive species can contribute to our knowledge of ecological processes – for example, community assembly and indirect interactions.

Population genetic structure and dispersal of Pinus occidentalis in the Dominican Republic by chloroplastic SSR with implications for its conservation, management, and reforestation

2021 ◽  
Author(s):  
Luis E. Rodríguez de Francisco ◽  
Rosanna Carreras-De León ◽  
Rafael M. Navarro Cerrillo ◽  
Liz A. Paulino-Gervacio ◽  
María-Dolores Rey ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Dominican Republic ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Conservation Management ◽  
Natural Populations ◽  
Limited Information ◽  
High Genetic Diversity ◽  
The Impact ◽  
Pinus Occidentalis

<i>Pinus occidentalis</i> is the dominant species of forest ecosystems in the Dominican Republic, located between 200 and 3000 meters above sea level, with extensive and overexploited natural populations. However, over the years, various restoration plans have been performed, which could affect the genetic structure of <i>P. occidentalis</i>. Despite being the species with the highest occurrence in the Dominican forests, there is no existing information on genetic structure and molecular characterization among natural populations with limited information on both phenological and productive characterization. In this study, the genetic structure, diversity, and gene flow of the five <i>P. occidentalis</i> natural populations of the Dominican Republic were determined using microsatellite markers. A total of 145 individuals were genotyped with eight polymorphic chloroplastic microsatellites, producing an average of 41 haplotypes with high genetic diversity across populations (H<sub>E</sub> = 0.90). Significant population genetic structure was found between populations (F<sub>ST</sub> = 0.123). These results reflect the impact of reforestation programs on natural populations and diluting the natural genetic signature. Analysis of population genetic data is, therefore, crucial for the breeding and conservation programs of <i>P. occidentalis</i> in the country.

Social Theory and the Study of Christian Missions in Africa

Africa ◽  
1974 ◽  
Vol 44 (3) ◽  
pp. 235-249 ◽  
Author(s):  
T. O. Beidelman
Keyword(s):  
Social Theory ◽  
Pacific Islanders ◽  
Theoretical Interest ◽  
Relevant Research ◽  
Broad Area ◽  
Christian Missions ◽  
The Past ◽  
Native Populations ◽  
Opening Paragraph ◽  
The Impact

Opening ParagraphIn the past anthropology was concerned with alien, exotic societies such as Indians, Africans, and Pacific Islanders. Today it is in vogue to do the anthropology of modern societies. Abroad this is termed the study of nation-building and development; at home it becomes the study of various sub-cultures with attention towards ethnic minorities and deviant groups rather than upon the more powerful and prominent segments of our society. Anthropologists tend to neglect those groups nearest themselves, and in the scurry to conduct relevant research, a broad area of great theoretical interest has been passed by. Almost no attention was ever paid by anthropologists to the study of colonial groups such as administrators, missionaries, or traders. Today we can read anthropological studies of the impact of such groups upon native populations, but the focus of such work dims with the colour line. Thus, an anthropologist has studied the machinations of the members of a Nigerian emirate but not the tactics of the British Resident and his staff. Another applied potted Weberian bureaucratic theory to Soga local government but neglected to discuss the British district officers in the same chiefdom. Another asked how Christian Tswana behaved, but not about those missionaries who had converted them. Anthropologists may have spoken about studying total societies, but they did not seem to consider their compatriots as subjects for wonder and analysis.* In the studies of Christianity in Africa, consideration was mainly in terms of the relations of the convert to his traditional society, to the process of social change, or sometimes to the development of native separatist churches. It never included the missionaries who had made the conversions or described everyday affairs at the mission station, clinic, or school.

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