The effect of survey method on the detection probabilities of frogs and tadpoles in large wetland complexes

2017 ◽  
Vol 68 (4) ◽  
pp. 686 ◽  
Author(s):  
Skye Wassens ◽  
Andrew Hall ◽  
Jennifer Spencer
Keyword(s):  
Survey Methods ◽  
Likelihood Estimation ◽  
Survey Method ◽  
Individual Species ◽  
Detection Probabilities ◽  
Poor Indicator ◽  
Frog Species ◽  
Species Combination ◽  
Bait Traps ◽  
Fyke Nets

Knowledge of the probability of detecting a species with a given survey effort is important when planning monitoring programs. The present paper compares detection probabilities for six survey methods: audio-visual transect surveys targeting adult frogs, and sweep netting, bait traps, small fyke nets, large fyke nets and seine netting targeting tadpoles. Data were drawn from repeat surveys of 16 wetlands over a 3-year period (2008–2011). Detection probabilities of each method and species combination were determined by maximum likelihood estimation. Audio-visual surveys targeting adults had a higher probability of detecting individual species than did methods targeting their tadpoles. However, the presence of adults was a reasonably poor indicator of the presence of their tadpoles on any given survey occasion. Of the methods employed to target tadpoles, large and small fyke nets had a significantly higher probability of detecting tadpoles of all species than did bait traps, seining or sweep nets. Differences in the detection probability of different methods demonstrated that the choice of survey method can bias towards particular groups of species and, in some cases, underestimate breeding activity by frog species in large waterbodies.

scholarly journals Estimating Detection Probability and Density from Point-Count Surveys: A Combination of Distance and Double-Observer Sampling

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 735-752 ◽  
Author(s):  
Michelle L. Kissling ◽  
Edward O. Garton
Keyword(s):  
Detection Probability ◽  
Survey Methods ◽  
Effective Area ◽  
Survey Method ◽  
Density Estimates ◽  
Point Count ◽  
Detection Probabilities ◽  
Fixed Radius ◽  
Count Surveys ◽  
Double Observer

Abstract Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, variable circular-plot (POVCP) technique to point-count surveys (n = 753) conducted in closed-canopy forests of southeast Alaska. Distance data were analyzed for each species to model a detection probability for each observer and calculate an estimate of density. We then multiplied each observer's density estimates by a correction factor to adjust for detection probabilities <1 at plot center. We compared analytical results from four survey methods: single-observer fixed-radius (50-m) plot; single-observer, variable circular-plot (SOVCP); double-observer fixed-radius (50-m) plot; and POVCP. We examined differences in detection probabilities at plot center, effective area surveyed, and densities for five bird species: Pacific-slope Flycatcher (Empidonax difficilis), Winter Wren (Troglodytes troglodytes), Golden-crowned Kinglet (Regulus satrapa), Hermit Thrush (Catharus guttatus), and Townsend's Warbler (Dendroica townsendi). Average detection probabilities for paired observers increased ≈8% (SE = 2.9) for all species once estimates were corrected for birds missed at plot center. Density estimators of fixed-radius survey methods were likely negatively biased, because the key assumption of perfect detection was not met. Density estimates generated using SOVCP and POVCP were similar, but standard errors were much lower for the POVCP survey method. We recommend using POVCP when study objectives require precise estimates of density. Failure to account for differences in detection probabilities and effective area surveyed results in biased population estimators and, therefore, faulty inferences about the population in question. Estimaciones de la Densidad y de las Probabilidades de Detección a Partir de Muestreos Utilizando Conteos en Puntos: Una Combinación de Muestreos de Distancia y de Doble Observador

Factors influencing detection probabilities of frogs in the monsoonal tropics of northern Australia: implications for the design of monitoring studies

2013 ◽  
Vol 40 (5) ◽  
pp. 393 ◽  
Author(s):  
P. L. Dostine ◽  
S. J. Reynolds ◽  
A. D. Griffiths ◽  
G. R. Gillespie
Keyword(s):  
Detection Probability ◽  
Individual Species ◽  
Sampling Effort ◽  
Northern Australia ◽  
Wet Season ◽  
Factors Influencing ◽  
Detection Probabilities ◽  
High Detection ◽  
Frog Species ◽  
A Site

Context Failure to acknowledge potential bias from imperfect detection of cryptic organisms such as frogs may compromise survey and monitoring programmes targeting these species. Aims The aims of the present study were to identify proximate factors influencing detection probabilities of a range of frog species in monsoonal northern Australia, and to estimate the number of repeat censuses required at a site to have confidence that non-detected species are absent. Methods Data on detection or non-detection of frog species based on calling individuals were recorded during 10 wet-season censuses of 29 survey sites in the Darwin region. Factors influencing detection probabilities were identified using occupancy models; model selection was based on the Akaike information criterion. Sampling effort for individual species was calculated using model predictions at different stages of the wet season. Key results The covariate water temperature featured in the best-supported models for 7 of the 14 frog species. Six of these species were more likely to be detected when water temperatures were below 30°C. Detection probabilities were also correlated with the number of days since the commencement of the wet season, time since last significant rainfall, air temperature and time after sunset. Required sampling effort for individual species varied throughout the wet season. For example, a minimum of two repeat censuses was required for detection of Litoria caerulea in the early wet season, but this number increased to 13 in the middle stage of the wet season. Conclusions Variability in environmental conditions throughout the wet season leads to variability in detection probabilities of frog species in northern Australia. Lower water temperatures, mediated by rainfall immediately before or during surveys, enhances detectability of a range of species. For most species, three repeat surveys under conditions resulting in a high detection probability are sufficient to determine presence at a site. Implications Survey and monitoring programmes for frogs in tropical northern Australia will benefit from the results of the present study by allowing targeting of conditions of high detection probability for individual species, and by incorporating sufficient repeat censuses to provide accurate assessment of the status of individual species at a site.

scholarly journals Estimating forest antelope population densities using distance sampling with camera traps

Oryx ◽  
2021 ◽  
pp. 1-7
Author(s):  
Rajan Amin ◽  
Hannah Klair ◽  
Tim Wacher ◽  
Constant Ndjassi ◽  
Andrew Fowler ◽  
...  
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Common Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Survey Tool ◽  
Terrestrial Mammals ◽  
Detection Probabilities ◽  
The Status

Abstract Traditional transect survey methods for forest antelopes often underestimate density for common species and do not provide sufficient data for rarer species. The use of camera trapping as a survey tool for medium and large terrestrial mammals has become increasingly common, especially in forest habitats. Here, we applied the distance sampling method to images generated from camera-trap surveys in Dja Faunal Reserve, Cameroon, and used an estimate of the proportion of time animals are active to correct for negative bias in the density estimates from the 24-hour camera-trap survey datasets. We also used multiple covariate distance sampling with body weight as a covariate to estimate detection probabilities and densities of rarer species. These methods provide an effective tool for monitoring the status of individual species or a community of forest antelope species, information urgently needed for conservation planning and action.

scholarly journals Design and Implementation of Android Applications as Mobile Payment Gateway Services in the Sistem Online Payment Point (SOPP) of PDAM Malang Regency

2015 ◽  
Vol 1 (1) ◽  
pp. 26-33
Author(s):  
Grifito yuan Maulidina
Keyword(s):  
User Satisfaction ◽  
Survey Methods ◽  
Survey Method ◽  
Point System ◽  
Payment Systems ◽  
Online Payment ◽  
Transaction Process ◽  
Inkjet Printers ◽  
Long Time ◽  
Speed Up

The development of online payment systems such as the online payment point system has greatly assisted the public in processing monthly transactions such as water bills. However, in its application, this system still uses large devices such as computers and inkjet printers so that the operation takes a long time and is less efficient. Therefore, in this study, a mobile application is designed to replace the role of computers in making water bill payment transactions in the online payment point system (SOPP) of PDAM Malang Regency. The application that is connected to a database server via the internet is also integrated with a compact wireless thermal printer that can be carried anywhere and does not require ink refills so that it can speed up the transaction process and be more efficient in time, paper and space. The research method used was experimental and survey methods. The experimental method is used to test the running of the application, test the application's compatibility with the device and measure the time it takes for the application to exchange data. The survey method is used to test user satisfaction with the application.

scholarly journals IMPLEMENTASI PROGRAM RENCANA PEMBANGUNAN JANGKA MENENGAH DAERAH (RPJMD) KABUPATEN KUTAI BARAT TAHUN 2011 - 2015

2019 ◽  
Vol 6 (2) ◽  
pp. 93
Author(s):  
Frans Christiyanto
Keyword(s):  
Data Analysis ◽  
Organizational Structure ◽  
Program Implementation ◽  
Quantitative Research ◽  
Qualitative Data ◽  
Survey Methods ◽  
Coefficient Of Determination ◽  
Survey Method ◽  
Analysis Tool ◽  
Independent Variables

The purpose of this paper is to analyze the effect of variable communication, resources, disposition and organizational structure for program implementation RPJMD West Kutai 2011-2015, either partially or simultaneously. Type of this research is quantitative research. The analysis tool used is multiple linear regression. In this study using survey methods explanation (explanatory survey method) is a survey that explains the variables under study and further analyze the influence between variables accompanied by hypothesis testing. This research was conducted by collecting qualitative data, which will then be presented in the form of numbers (quantified) to be tested in accordance with the design verification of data analysis. The results showed the coefficient of determination (R2) of 0.421. There is significant influence between independent variables namely communication, resources, disposition and organizational structure for program implementation RPJMD West Kutai 2011-2015.Keyword: Implementation RPJMD, Communication, Resources

Pits or pictures: a comparative study of camera traps and pitfall trapping to survey small mammals and reptiles

2019 ◽  
Vol 46 (2) ◽  
pp. 104 ◽  
Author(s):  
Shannon J. Dundas ◽  
Katinka X. Ruthrof ◽  
Giles E. St.J. Hardy ◽  
Patricia A. Fleming
Keyword(s):  
Community Composition ◽  
Small Mammals ◽  
Survey Methods ◽  
Infrared Camera ◽  
Camera Traps ◽  
Camera Trapping ◽  
Survey Method ◽  
Pitfall Traps ◽  
Pitfall Trapping ◽  
Trapping Methods

Context Camera trapping is a widely used monitoring tool for a broad range of species across most habitat types. Camera trapping has some major advantages over other trapping methods, such as pitfall traps, because cameras can be left in the field for extended periods of time. However, there is still a need to compare traditional trapping methods with newer techniques. Aims To compare trap rates, species richness and community composition of small mammals and reptiles by using passive, unbaited camera traps and pitfall traps. Methods We directly compared pitfall trapping (20-L buried buckets) with downward-facing infrared-camera traps (Reconyx) to survey small reptiles and mammals at 16 sites within a forested habitat in south-western Australia. We compared species captured using each method, as well as the costs associated with each. Key results Overall, we recorded 228 reptiles, 16 mammals and 1 frog across 640 pitfall trap-nights (38.3 animal captures per 100 trap-nights) compared to 271 reptiles and 265 mammals (for species likely to be captured in pitfall traps) across 2572 camera trap nights (20.8 animal captures per 100 trap-nights). When trap effort is taken into account, camera trapping was only 23% as efficient as pitfall trapping for small reptiles (mostly Scincidae), but was five times more efficient for surveying small mammals (Dasyuridae). Comparing only those species that were likely to be captured in pitfall traps, 13 species were recorded by camera trapping compared with 20 species recorded from pitfall trapping; however, we found significant (P&lt;0.001) differences in community composition between the methods. In terms of cost efficacy, camera trapping was the more expensive method for our short, 4-month survey when taking the cost of cameras into consideration. Conclusions Applicability of camera trapping is dependent on the specific aims of the intended research. Camera trapping is beneficial where community responses to ecosystem disturbance are being tested. Live capture of small reptiles via pitfall trapping allows for positive species identification, morphological assessment, and collection of reference photos to help identify species from camera photos. Implications As stand-alone techniques, both survey methods under-represent the available species present in a region. The use of more than one survey method improves the scope of fauna community assessments.

scholarly journals Incorporating Availability for Detection in Estimates of Bird Abundance

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Duane R. Diefenbach ◽  
Matthew R. Marshall ◽  
Jennifer A. Mattice ◽  
Daniel W. Brauning
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Sampling Period ◽  
Bird Abundance ◽  
Point Counts ◽  
Variance Estimators ◽  
Bird Survey ◽  
Detection Probabilities ◽  
Ammodramus Henslowii ◽  
Further Development

Abstract Several bird-survey methods have been proposed that provide an estimated detection probability so that bird-count statistics can be used to estimate bird abundance. However, some of these estimators adjust counts of birds observed by the probability that a bird is detected and assume that all birds are available to be detected at the time of the survey. We marked male Henslow's Sparrows (Ammodramus henslowii) and Grasshopper Sparrows (A. savannarum) and monitored their behavior during May-July 2002 and 2003 to estimate the proportion of time they were available for detection. We found that the availability of Henslow's Sparrows declined in late June to <10% for 5- or 10-min point counts when a male had to sing and be visible to the observer; but during 20 May-19 June, males were available for detection 39.1% (SD = 27.3) of the time for 5-min point counts and 43.9% (SD = 28.9) of the time for 10-min point counts (n = 54). We detected no temporal changes in availability for Grasshopper Sparrows, but estimated availability to be much lower for 5-min point counts (10.3%, SD = 12.2) than for 10-min point counts (19.2%, SD = 22.3) when males had to be visible and sing during the sampling period (n = 80). For distance sampling, we estimated the availability of Henslow's Sparrows to be 44.2% (SD = 29.0) and the availability of Grasshopper Sparrows to be 20.6% (SD = 23.5). We show how our estimates of availability can be incorporated in the abundance and variance estimators for distance sampling and modify the abundance and variance estimators for the double-observer method. Methods that directly estimate availability from bird counts but also incorporate detection probabilities need further development and will be important for obtaining unbiased estimates of abundance for these species. Incorporación de la Disponibilidad para la Detección en las Estimaciones de Abundancia de Aves

scholarly journals Faktor Internal dan Eksternal yang Menentukan Non Performing Financing (NPF) pada Pembiayaan Mudharabah

2021 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Rahdya Iasyah Nindea Tami
Keyword(s):  
Survey Methods ◽  
Rapid Development ◽  
Secondary Data ◽  
Sampling Technique ◽  
Primary Data ◽  
Survey Method ◽  
Validity And Reliability ◽  
Purposive Sampling ◽  
Bank Management ◽  
Bank Employees

Abstract. In recent years, the world of Islamic banking in Indonesia has shown very rapid development, both in terms of the number of new office openings, types of bank businesses and the volume of bank activities they do. Al Salaam SRBs are BPRS that are superior compared to other SRBs in the city of Bandung. However, the level of BPRS Al Salaam's problematic financing (NPF) was the highest among other BPRS. The problematic financing that occurred at the Al Salaam SRB was due to several factors and processes that did not occur quickly, where these factors could be sourced from bank management aspects as well as customer aspects. This study aims to identify the Internal and External Factors that determine Non-Performing Financing (NPF) in mudharabah financing at Al Salaam Bandung Branch. This type of research used in this research is quantitative descriptive research with survey methods. The survey method was carried out by interviewing and distributing questionnaires to 10 respondents namely 5 bank management parties and 5 customers. Sampling is done by simple calculations using purposive sampling technique. Data sources used in this study consisted of two types, namely secondary data and primary data. The analytical method used is the Likert scale analysis method. Test requirements analysis using validity and reliability tests are assisted using the SPSS program. The results showed that aspects of bank management from the perspective of bank employees and customers are at sufficient intervals to determine the occurrence of problematic financing or NPF while customer aspects from the perspective of bank employees and customers themselves are at intervals determining the occurrence of problematic financing or NPF.   Abstrak. Pada tahun-tahun terakhir ini dunia perbankan Syariah di Indonesia menunjukkan perkembangan yang sangat pesat, baik dilihat dari jumlah pembukaan kantor baru, jenis usaha bank dan volume kegiatan bank yang dilakukannya. BPRS Al Salaam termasuk BPRS yang lebih unggul dibandingkan dengan BPRS lainnya di kota Bandung. Namun demikian, tingkat pembiayaan bermasalah (NPF) BPRS Al Salaam pun paling tinggi diantara BPRS lainnya. Pembiayaan bermasalah yang terjadi di BPRS Al Salaam disebabkan beberapa faktor dan proses yang tidak terjadi secara cepat, dimana faktor tersebut dapat bersumber dari aspek manajemen bank maupun aspek nasabah. Penelitian ini bertujuan untuk mengidentifikasi Faktor Internal dan Eksternal yang menentukan Non Performing Financing (NPF) pada pembiayaan mudharabah di BPRS Al Salaam Cabang Bandung.Jenis penelitian yang digunakan dalam penelitian ini adalah penelitian deskriptif kuantitatif dengan metode survei. Metode survei dilakukan dengan wawancara dan menyebarkan kuisioner kepada 10 responden yaitu pihak manajemen bank sebanyak 5 orang dan pihak nasabah sebanyak 5 orang. Pengambilan sampel dilakukan dengan perhitungan sederhana menggunakan teknik purposive sampling. Sumber data yang digunakan dalam penelitian ini terdiri dari dua jenis yaitu data sekunder dan data primer. Metode analisis yang digunakan adalah metode analisis skala likert. Uji persyaratan analisis menggunakan uji validitas dan reabilitas dibantu menggunakan program SPSS.Hasil penelitian menunjukkan bahwa aspek manajemen bank menurut perspektif karyawan bank maupun nasabah berada pada interval cukup menentukan terjadinya pembiayaan bermasalah atau NPF sedangkan Aspek nasabah menurut perspektif karyawan bank maupun nasabah itu sendiri berada pada interval menentukan terjadinya pembiayaan bermasalah atau NPF.

scholarly journals A theory for ecological survey methods to map individual distributions

2017 ◽  
Author(s):  
Nao Takashina ◽  
Maria Beger ◽  
Buntarou Kusumoto ◽  
Suren Rathnayake ◽  
Hugh P. Possingham
Keyword(s):  
Point Processes ◽  
Spatial Scales ◽  
Survey Methods ◽  
Survey Method ◽  
Management Decision ◽  
Spatially Explicit ◽  
Mapping Unit ◽  
Ecological Survey ◽  
Multiple Spatial Scales ◽  
Management Actions

AbstractSpatially-explicit approaches are widely recommended for ecosystem management. The quality of the data, such as presence/absence or habitat maps, affects the management actions recommended, and is, therefore, key to management success. However, available data are often biased and incomplete. Previous studies have advanced ways to resolve data bias and missing data, but questions remain about how we design ecological surveys to develop a dataset through field surveys. Ecological surveys may have multiple spatial scales, including the spatial extent of the target ecosystem (observation window), the resolution for mapping individual distributions (mapping unit), and the survey area within each mapping unit (sampling unit). We developed an ecological survey method for mapping individual distributions by applying spatially-explicit stochastic models. We used spatial point processes to describe individual spatial placements using either random or clustering processes. We then designed ecological surveys with different spatial scales and individual detectability. We found that the choice of mapping unit affected the presence mapped fraction, and the fraction of the total individuals covered by the presence mapped patches. Tradeoffs were found between these quantities and the map resolution, associated with equivalent asymptotic behaviors for both metrics at sufficiently small and large mapping unit scales. Our approach enabled consideration of the effect of multiple spatial scales in surveys, and estimation of the survey outcomes such as the presence mapped fraction and the number of individuals situated in the presence detected units. The developed theory may facilitate management decision-making and inform the design of monitoring and data gathering.

scholarly journals Learning to count: adapting population monitoring for Endangered huemul deer Hippocamelus bisulcus to meet conservation objectives

2020 ◽  
Author(s):  
Heiko Wittmer ◽  
P Corti ◽  
C Saucedo ◽  
J Galaz
Keyword(s):  
Survey Data ◽  
Survey Methods ◽  
Cost Effective ◽  
Population Monitoring ◽  
Population Trends ◽  
Monitoring Methods ◽  
Monitoring Method ◽  
Hippocamelus Bisulcus ◽  
Detection Probabilities ◽  
Current Survey

Considerable efforts have been invested in recent years to improve methods for both data collection and analyses required for population monitoring. Where historical or current estimates of population size are not adjusted for detection probabilities they may be too inaccurate to provide meaningful estimates of trends and thus monitoring methods need to be adapted. Here, we use data from the Endangered huemul deer Hippocamelus bisulcus to outline a framework to develop accurate robust estimates of detection probabilities that can be incorporated into new surveys in a cost-effective way and applied to existing survey data sets. In particular, by retroactively estimating detection probabilities for surveys of huemul, we show that current survey methods for huemul are inadequate to determine population trends reliably. Based on these results we propose a new monitoring method for the huemul and discuss the importance of estimating accuracies of historical survey data to ensure that changes in the abundance of the species reflect real population trends and are not an artefact of variation over time in the accuracy of survey data. © 2010 Fauna & Flora International.

Sign in / Sign up

Export Citation Format

Share Document