scholarly journals Contact rates with nesting birds before and after invasive snake removal: estimating the effects of trap-based control

NeoBiota ◽  
2019 ◽  
Vol 49 ◽  
pp. 1-17 ◽  
Author(s):  
Amy A. Yackel Adams ◽  
Melia G. Nafus ◽  
Page E. Klug ◽  
Björn Lardner ◽  
M. J. Mazurek ◽  
...  
Keyword(s):  
Forest Birds ◽  
Native Forest ◽  
Prey Selectivity ◽  
Control Techniques ◽  
Brown Treesnake ◽  
Contact Rates ◽  
Invasive Predators ◽  
Invasive Predator ◽  
Before And After ◽  
Trapping Grid

Invasive predators are responsible for almost 60% of all vertebrate extinctions worldwide with the most vulnerable faunas occurring on islands. The brown treesnake (Boigairregularis) is a notorious invasive predator that caused the extirpation or extinction of most native forest birds on Guam. The success of avian reintroduction efforts on Guam will depend on whether snake-control techniques sufficiently reduce contact rates between brown treesnakes and reintroduced birds. Mouse-lure traps can successfully reduce brown treesnake populations at local scales. Over a 22-week period both with and without active snake removal, we evaluated snake-trap contact rates for mouse- and bird-lure traps. Bird-lure traps served as a proxy for reintroduced nesting birds. Overall, mouse-lure traps caught more snakes per trap night than did bird-lure traps. However, cameras revealed that bird-lure traps had a snake contact rate almost 15 times greater than the number of successfully captured snakes. Snakes that entered bird-lure traps tended to be larger and in better body condition and were mostly captured in bird-lure traps, despite numerous adjacent mouse-lure traps. Traps placed along grid edges caught more snakes than interior traps, suggesting continuous immigration into the trapping grid within which bird-lure traps were located. Contact between snakes and bird-lure traps was equivalent before and after snake removal, suggesting mouse-lure traps did not adequately reduce the density of snakes that posed a risk to birds, at least at the timescale of this project. This study provides evidence that some snakes exhibit prey selectivity for live birds over live mouse lures. Reliance on a single control tool and lure may be inadequate for support of avian reintroductions and could lead to unintended harvest-driven trait changes of this invasive predator.

scholarly journals Functional group-dependent responses of forest bird communities to invasive predator control and habitat fragmentation

2021 ◽  
Author(s):  
Shaun Morgan ◽  
Nigel A. Binks ◽  
Raphael K. Didham ◽  
Andrew D. Barnes
Keyword(s):  
Habitat Fragmentation ◽  
Bird Communities ◽  
Native Forest ◽  
Forest Fragments ◽  
Predator Control ◽  
Bird Abundance ◽  
Invasive Predators ◽  
Invasive Predator ◽  
Invasive Mammals ◽  
Native Birds

AbstractAimMounting global pressure on bird populations from invasive predators and habitat loss has driven a rapid growth in restorative and protective conservation action around the world, yet the efficacy of such actions is still not well understood. We investigated the relative effects of invasive predator control and habitat fragmentation on the abundance of native birds and invasive mammalian predators in native forest fragments.LocationWaikato region, New ZealandMethodsWe sampled invasive mammalian predator and native bird abundances using camera traps and bird counts at 26 sites in 15 forest fragments across New Zealand’s Waikato region. Fragment area, shape complexity, and surrounding land cover of exotic and native forest were determined in ArcMap. We further created two composite gradients reflecting predator control intensity and temporal distribution of control based on seven quantitative variables recorded in each of the five years preceding native bird data collection. Finally, we estimated the relative influence of these drivers on invasive mammals and functional groups of native birds using model averaging.ResultsOf the two invasive predator control variables, only control intensity significantly affected invasive predator abundance and was also a more important driver than landscape or fragment structure, but responses varied among invasive mammal species. In contrast, both invasive predator control intensity and fragment structure were similarly important drivers of native bird abundance, though bird community responses varied markedly between functional groups.Main conclusionsOur findings suggest that spatial extent of invasive mammal control is important for controlling mammal numbers and enhancing bird abundance, especially for small insectivorous species, and that habitat fragmentation is less important for invasive mammals but at least as important for native bird communities. Consequently, both drivers should be given strong consideration when undertaking landscape-scale conservation and restoration of bird communities in human-altered landscapes threatened by invasive predators.

Evolution or Extinction: Might Zooplankton Adaptively Respond to the Novel Invasive Predator Bythotrephes longimanus?

2018 ◽  
Author(s):  
Emma Bloomfield
Keyword(s):  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Prey Species ◽  
Rapid Evolution ◽  
Freshwater Ecosystems ◽  
Bythotrephes Longimanus ◽  
Economic Implications ◽  
Invasive Predators ◽  
Invasive Predator ◽  
Introduced Predators

Invasive predators are a large and growing threat to species diversity and human well-being. One of the reasons invasive predators have a negative impact is that native prey species do not possess appropriate anti-predator defenses. However, rapid evolution may allow prey species to respond adaptively to introduced predators. When this occurs the impacts of invasive predators are mitigated. An invasive predator that is of concern in North America is the spiny water flea, Bythotrephes longimanus. It disrupts freshwater ecosystems through voracious consumption of zooplankton. Declines in zooplankton abundance and richness reduce water quality and recreational fishing opportunities. However, a species of zooplankton, Daphnia mendotae has been found to adaptively respond to B. longimanus. This adaptation is diel vertical migration, the behavioral change of occupying a lower position in the water column during the day to reduce predation risk. Despite the ecological and economic implications of this behavior in response to B. longimanus, it has only been studied in a few lakes. This study investigated adaptive diel vertical migration in D. mendotae from multiple lakes. This was done by measuring the vertical position of D. mendotae in artificial water columns. It was hypothesized that D. mendotae from lakes that have been invaded by B. longimanus will exhibit diel vertical migration in the presence of B. longimanus. If this hypothesis is supported, rapid evolution of diel vertical migration can be established as a widespread response. This would strengthen understanding of rapid evolution and allow lakes more vulnerable to B.longimanus to be identified.

scholarly journals Anthropocene rockfalls travel farther than prehistoric predecessors

2016 ◽  
Vol 2 (9) ◽  
pp. e1600969 ◽  
Author(s):  
Josh Walter Borella ◽  
Mark Quigley ◽  
Louise Vick
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Anthropogenic Activity ◽  
Native Forest ◽  
Rockfall Hazard ◽  
Geologic Hazards ◽  
Human Modification ◽  
Before And After ◽  
European Colonization ◽  
And Behavior

Human modification of natural landscapes has influenced surface processes in many settings on Earth. Quantitative data comparing the distribution and behavior of geologic phenomena before and after human arrival are sparse but urgently required to evaluate possible anthropogenic influences on geologic hazards. We conduct field and imagery-based mapping, statistical analysis, and numerical modeling of rockfall boulders triggered by the fatal 2011 Christchurch earthquakes (n= 285) and newly identified prehistoric (Holocene and Pleistocene) boulders (n= 1049). Prehistoric and modern boulders are lithologically equivalent, derived from the same source cliff, and yield consistent power-law frequency-volume distributions. However, a significant population of modern boulders (n= 26) traveled farther downslope (>150 m) than their most-traveled prehistoric counterparts, causing extensive damage to residential dwellings at the foot of the hillslope. Replication of prehistoric boulder distributions using three-dimensional rigid-body numerical models that incorporate lidar-derived digital topography and realistic boulder trajectories and volumes requires the application of a drag coefficient, attributed to moderate to dense slope vegetation, to account for their spatial distribution. Incorporating a spatially variable native forest into the models successfully predicts prehistoric rockfall distributions. Radiocarbon dating provides evidence for 17th to early 20th century deforestation at the study site during Polynesian and European colonization and after emplacement of prehistoric rockfall. Anthropocene deforestation enabled modern rockfalls to exceed the limits of their prehistoric predecessors, highlighting a shift in the geologic expression of rockfalls due to anthropogenic activity. Reforestation of hillslopes by mature native vegetation could help reduce future rockfall hazard.

scholarly journals Population growth estimates of a threatened seabird indicate necessity for additional management following invasive predator eradications

2020 ◽  
Author(s):  
Johannes Fischer ◽  
GA Taylor ◽  
R Cole ◽  
I Debski ◽  
DP Armstrong ◽  
...  
Keyword(s):  
Population Growth ◽  
Native Species ◽  
Linear Models ◽  
Monitoring Methods ◽  
Apparent Lack ◽  
Zoological Society ◽  
Invasive Predators ◽  
Invasive Predator ◽  
Rate Of Increase ◽  
Log Linear

© 2019 The Zoological Society of London The eradication of invasive predators from islands is a successful technique to safeguard seabird populations, but adequate post-eradication monitoring of native species is often lacking. The Whenua Hou Diving Petrel (Pelecanoides whenuahouensis; WHDP) is a recently-described and ‘Critically Endangered’ seabird, restricted to Codfish Island (Whenua Hou), New Zealand. Invasive predators, considered the major threat to WHDP, were eradicated on Codfish Island in 2000. However, estimates of WHDP population size and trends remain unknown, hindering assessments of the success of the eradications. We collated intermittent burrow counts (n = 20 seasons) conducted between 1978 and 2018. To estimate the population growth rate (λ) before and after predator eradications, we used log-linear models in a Bayesian hierarchical framework while retrospectively accounting for differences in detection probabilities among burrow counts, due to differences in effort, marking and timing. The number of WHDP burrows was estimated at 40 (36–46) in 1978 and 100 (97–104) in 2018. The pre-eradication λ was estimated at 1.023 (0.959–1.088), while the post-eradications λ was estimated at 1.017 (1.006–1.029). The WHDP population appears to be increasing, yet the rate of increase is low compared to other Procellariiformes following predator eradications. The comparatively low post-eradication λ, combined with an apparent lack of change between pre- and post-eradication λ, indicates that additional threats might be limiting WHDP population growth and that further conservation management is required. The continuation of affordable and simple, albeit imperfect, monitoring methods with retrospective corrections facilitated the assessment of invasive predator eradications outcomes and should guide future management decisions. An abstract in Te Reo Māori (the Māori language) can be found in Appendix S1.

The Native Forest Birds of Guam

1983 ◽  
pp. ii-61 ◽  
Author(s):  
J. Mark Jenkins
Keyword(s):  
Forest Birds ◽  
Native Forest

Population recovery of common brushtail possums after local depopulation

2004 ◽  
Vol 31 (5) ◽  
pp. 543 ◽  
Author(s):  
Weihong Ji ◽  
Stephen D. Sarre ◽  
Piran C. L. White ◽  
Mick N. Clout
Keyword(s):  
Biological Control Agent ◽  
Integrated Control ◽  
Seasonal Fluctuation ◽  
Control Program ◽  
Control Agent ◽  
Native Forest ◽  
Population Recovery ◽  
Adult Males ◽  
Contact Rates ◽  
Reduced Density

Brushtail possums (Trichosurus vulpecula) were live-trapped for two years prior to and following depopulation in two ~6-ha areas of native forest in New Zealand. The populations had recovered to 55% of the original density at one site and 40% of the original density at the other site, two years after the depopulation. The post-removal populations responded to reduced density with a higher proportion of females breeding, higher survival rate of young, and less seasonal fluctuation in body condition. The initial recolonisation was probably mainly due to surrounding animals shifting their ranges into the depopulated area, rather than long-range dispersal, which resulted in an even sex ratio in the recovering populations. The greater proportion of adult males in the post-removal populations is likely to increase sexual contact rates for females. This would enhance the dissemination of a viral-vectored biological control agent through the population, when used as part of an integrated control program.

scholarly journals Reconstruction of the Switched Reluctance Motor Stator

2012 ◽  
Vol 63 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Eyhab El-Kharashi ◽  
Hany Hassanien
Keyword(s):  
Classical Method ◽  
Dynamic Performance ◽  
Switched Reluctance Motor ◽  
Stator Core ◽  
Switched Reluctance ◽  
Control Techniques ◽  
Pi Controllers ◽  
Reluctance Motor ◽  
Before And After ◽  
Artificial Neural Network Ann

Reconstruction of the Switched Reluctance Motor Stator The paper re-designs the conventional 6/8 switched reluctance motor (SRM) by a particular way to minimize the losses. The flux loops are shortened by making each two stator teeth incorporated in one magnetic circuit only. Subsequently the flux does not cross in some iron parts of the stator core backs. These unused iron sections are taken off consequently the iron losses decreased. Now the stator consists of three separated sections and they are fixed inside non-magnetic cylinder. The copper losses also are decreased because less copper windings are used to produce the same amount of the output torque as the flux paths become short then the flux density increases. The analysis and comparison of the 6/8 SRM before and after the re-design process are presented. A m files Matlab software is used to simulate the dynamic performance. Then the paper proceeds to examine different control techniques to the new design. The hysteresis and PI controllers are used as classical method to control the SRM. Then the artificial neural network (ANN) is used to test the new control techniques.

scholarly journals Population growth estimates of a threatened seabird indicate necessity for additional management following invasive predator eradications

2020 ◽  
Author(s):  
Johannes Fischer ◽  
GA Taylor ◽  
R Cole ◽  
I Debski ◽  
DP Armstrong ◽  
...  
Keyword(s):  
Population Growth ◽  
Native Species ◽  
Linear Models ◽  
Monitoring Methods ◽  
Apparent Lack ◽  
Zoological Society ◽  
Invasive Predators ◽  
Invasive Predator ◽  
Rate Of Increase ◽  
Log Linear

© 2019 The Zoological Society of London The eradication of invasive predators from islands is a successful technique to safeguard seabird populations, but adequate post-eradication monitoring of native species is often lacking. The Whenua Hou Diving Petrel (Pelecanoides whenuahouensis; WHDP) is a recently-described and ‘Critically Endangered’ seabird, restricted to Codfish Island (Whenua Hou), New Zealand. Invasive predators, considered the major threat to WHDP, were eradicated on Codfish Island in 2000. However, estimates of WHDP population size and trends remain unknown, hindering assessments of the success of the eradications. We collated intermittent burrow counts (n = 20 seasons) conducted between 1978 and 2018. To estimate the population growth rate (λ) before and after predator eradications, we used log-linear models in a Bayesian hierarchical framework while retrospectively accounting for differences in detection probabilities among burrow counts, due to differences in effort, marking and timing. The number of WHDP burrows was estimated at 40 (36–46) in 1978 and 100 (97–104) in 2018. The pre-eradication λ was estimated at 1.023 (0.959–1.088), while the post-eradications λ was estimated at 1.017 (1.006–1.029). The WHDP population appears to be increasing, yet the rate of increase is low compared to other Procellariiformes following predator eradications. The comparatively low post-eradication λ, combined with an apparent lack of change between pre- and post-eradication λ, indicates that additional threats might be limiting WHDP population growth and that further conservation management is required. The continuation of affordable and simple, albeit imperfect, monitoring methods with retrospective corrections facilitated the assessment of invasive predator eradications outcomes and should guide future management decisions. An abstract in Te Reo Māori (the Māori language) can be found in Appendix S1.

scholarly journals Applying the SEIR Model in Forecasting The COVID-19 Trend in Malaysia: A Preliminary Study

2020 ◽  
Author(s):  
Aidalina Mahmud ◽  
Poh Ying Lim
Keyword(s):  
Community Health ◽  
Movement Control ◽  
Senior Lecturer ◽  
Epidemic Curve ◽  
Contact Rates ◽  
Health Specialist ◽  
Before And After ◽  
Preliminary Study ◽  
Using Data ◽  
Control Order

AbstractOn March 18, 2020 the Malaysian government implemented a 14-day Movement Control Order (MCO) as part of the mitigation plan in controlling the COVID-19 epidemic in the country. The MCO aims to limit the contact rates among the population and hence prevent the surge of infected individuals. However, the trend of the epidemic before and after the MCO was not apparent. By applying the Susceptible, Exposed, Infectious and Removed (SEIR) mathematical model, we aimed to forecast the trend of COVID-19 epidemic in Malaysia using data from March 17 to 27, 2020. Based on several predetermined assumptions, the results of the analyses showed that after the implementation of the 14-day MCO from March 18 to 31, 2020, it is forecasted that the epidemic in Malaysia will peak approximately in the end of April 2020 and will subside by about the first week of July 2020. The MCO will “flatten the epidemic curve” but will prolong the duration of the epidemic. Decision to extend the duration of the MCO should depend on the consideration of socioeconomic factors as well.Author summaryDr. Aidalina Mahmud is a Public Health Specialist and a medical lecturer in the Department of Community Health, Universiti Putra Malaysia. Dr. Lim Poh Ying is a Biostatistician and is a senior lecturer in the Department of Community Health, Universiti Putra Malaysia.

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