A Test of the Accuracy of Line and Strip Transect Estimators in Aerial Survey

1988 ◽  
Vol 15 (5) ◽  
pp. 493 ◽  
Author(s):  
J Hone
Keyword(s):  
Fourier Series ◽  
Hermite Polynomial ◽  
Aerial Survey ◽  
Survey Method ◽  
Line Transect ◽  
Accuracy And Precision ◽  
Exponential Power ◽  
Negative Exponential ◽  
Similar Accuracy ◽  
Strip Transect

The accuracy and precision of eight line transect estimators and one strip transect estimator were examined by helicopter aerial survey. Carcasses of feral pigs were counted in an area of treeless floodplain and Eucalyptus woodland. The ratio and Cox's methods, Fourier series, exponential power series, half-normal, exponential polynomial, negative exponential, hermite polynomial and hazard rate estimators gave accurate estimates. Using the survey method described, most estimators were of similar accuracy and precision, but the Fourier series estimator was the most accurate.

Comparison of Helicopter Line Transects with Walked Line Transects for Estimating Densities of Kangaroos

1997 ◽  
Vol 24 (4) ◽  
pp. 397 ◽  
Author(s):  
T. F. Clancy ◽  
A. R. Pople ◽  
L. A. Gibson
Keyword(s):  
Repeated Measures ◽  
Aerial Survey ◽  
Survey Method ◽  
Line Transect ◽  
Attractive Alternative ◽  
Line Transect Sampling ◽  
Density Estimates ◽  
Transect Sampling ◽  
Grey Kangaroo ◽  
Line Transects

The performance of helicopter surveys for estimating population densities of red kangaroos (Macropus rufus), eastern grey kangaroos (Macropus giganteus) and common wallaroos (Macropus robustus) was investigated by comparing line-transect density estimates obtained from helicopter surveys with those from ground (walked) surveys. Comparisons were made at four sites in central western Queensland (areas with high densities of red kangaroos and common wallaroos) that were surveyed during winter and summer from December 1991 until February 1995, and one site in south-eastern Queensland (an area of high eastern grey kangaroo density) surveyed annually during autumn from March 1991 until March 1994. Helicopter surveys generally recorded lower sample sizes than did ground surveys (means ± s.e = 34 ± 6%, 33 ± 9% and 76 ± 2% lower for red kangaroos, eastern grey kangaroos and wallaroos, respectively). Density estimates obtained from the helicopter surveys were not significantly different from those obtained from ground surveys for both red and eastern grey kangaroos as assessed by repeated-measures ANOVA and regression analysis. However, helicopter surveys of common wallaroos consistently returned density estimates about half those of ground surveys. The relationships between the two methods did not differ between winter and summer for any species. The conventional aerial survey method for kangaroos of strip transects from fixed-wing aircraft has limited ability to adjust for varying sightability conditions. Therefore, helicopter surveys with line-transect sampling are an attractive alternative.

scholarly journals Comparison of Surveys of Kangaroos in Queensland Using Helicopters and Fixed-Wing Aircraft.

1998 ◽  
Vol 20 (1) ◽  
pp. 92 ◽  
Author(s):  
AR Pople ◽  
SC Cairns ◽  
TF Clancy ◽  
GC Grigg ◽  
LA Beard ◽  
...  
Keyword(s):  
Aerial Survey ◽  
Population Estimates ◽  
Line Transect ◽  
Correction Factors ◽  
Density Estimates ◽  
Australian State ◽  
Transect Counts ◽  
Comparative Accuracy ◽  
Harvest Quotas ◽  
Strip Transect

Kangaroo harvest quotas for each Australian state have been set mainly as proportions of population estimates derived from aerial surveys. Estimating population size from strip transect counts using fixed- wing aircraft has become an established technique, but counts must be adjusted by correction factors to ensure population estimates are both accurate and repeatable. Surveys of kangaroos in Queensland are currently conducted with helicopters using line transect methodology, but cost restricts their use to relatively small survey blocks. Nevertheless, they return more accurate and repeatable estimates of kangaroo density than surveys with fixed-wing aircraft. A comparison of the above two techniques was made along the same transect lines in seven survey blocks (5000-10,000 km2) in southern and western Queensland, allowing an assessment of the comparative accuracy of the fixed-wing method. For red kangaroos (Macropus rufus), required correction factors of 0.7-3.1 were similar to those used previously. However, for eastern grey kangaroos (M. giganteus), substantially larger correction factors of 3.4-10.2 were needed to approach true density. For wallaroos (M. robustus), correction factors of 3.8-4.8 were required, but can be considered conservative because helicopter-derived density estimates are known to be underestimated by a factor of 2-3. Further work is needed to establish how correction factors for each species should be applied on a broader scale and whether they lead to repeatable estimates of kangaroo density. Key words: aerial survey, line transect, correction factors, strip transect, wallaroo.

scholarly journals Caribou distribution during calving in the northeast National Petroleum Reserve-Alaska, June 1998 to 2000

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 283 ◽  
Author(s):  
Lynn E. Noel ◽  
John C. George
Keyword(s):  
Survey Methodology ◽  
Aerial Survey ◽  
Small Sample ◽  
Telemetry Data ◽  
Minimum Convex Polygon ◽  
Survey Period ◽  
Private Industry ◽  
Coverage Area ◽  
Cow Calf ◽  
Strip Transect

Barren ground caribou (Rangifer tarandus granti) of the Teshekpuk Caribou Herd (TCH) inhabit the western portion of Alaska's Arctic Coastal Plain within the National Petroleum Reserve—Alaska (NPR-A). Alaska's North Slope communities, management agencies, and private industry are interested in this herd because of its importance as a subsistence resource and location relative to potential petroleum development. From 1998 through 2000, we monitored caribou distribution during the calving period within the Northeast Planning Area of the NPR-A using systematic strip-transect aerial surveys, as well as VHF and satellite telemetry for cow caribou. Aerial survey and telemetry data indicated cows with calves were distributed around Teshekpuk Lake, with a concentration south of the lake in 1999 and 2000. Inconsistencies in weather conditions, survey timing (both strip-transect and VHF surveys), 100% coverage survey areas, and small sample sizes confound interpretations of our results. However, several patterns were apparent. Later transect survey timing (7—12 June versus 4—7 and 5—8 June) resulted in more cow/calf pairs recorded. Our 18% coverage area, originally based on VHF telemetry data for the extent of TCH calving, covered a consistently high proportion (95% to 100%) of the annual calving ranges (95% kernel utilization distributions), but accounted for only 24% to 46% of the adult cows in the TCH based on the current Alaska Department of Fish and Game population estimate (1999) and average 1998¬2000 herd composition. It appears that either our transect survey methodology significantly underestimated the true number of caribou cows in the study area, many cows calved outside the area or moved into the area and calved after our surveys, or we have over estimated the number of reproductive cows in the herd. Our 100% coverage transect areas covering oil and gas lease areas, contained 38% of the calving range with 23% of TCH cows in 1999; and 18% of the calv¬ing range with 8% of TCH cows in 2000. Based on 95% minimum convex polygon ranges, satellite collared cow/calf pairs were not stationary during either our survey period (14.7 ± 6.56 km2; mean ± standard error of the mean; 4—12 June) or during the calving period (86.9 ± 72.30 km2; 1—20 June) during 1998—2000. Site specific pre-development data on caribou distribution during calving in NPR-A will be useful for assessing the importance of specific areas to caribou during calving and for designing oilfields that minimize impacts should oil development occur.

A Note on the Fourier Series Model for Analysing Line Transect Data

Biometrics ◽  
1982 ◽  
Vol 38 (2) ◽  
pp. 469 ◽  
Author(s):  
Stephen T. Buckland
Keyword(s):  
Fourier Series ◽  
Line Transect

scholarly journals Aerial line transect survey to estimate abundance of marsh deer (Blastocerus dichotomus) (Illiger, 1815)

2005 ◽  
Vol 48 (5) ◽  
pp. 807-814 ◽  
Author(s):  
Artur Andriolo ◽  
Ubiratan Piovezan ◽  
Mateus José Rodrigues Paranhos da Costa ◽  
Jeff Laake ◽  
José Maurício Barbanti Duarte
Keyword(s):  
Population Size ◽  
River Basin ◽  
Distance Sampling ◽  
Aerial Survey ◽  
Line Transect ◽  
Sampling Methodology ◽  
Future Analysis ◽  
Line Transect Survey ◽  
Blastocerus Dichotomus ◽  
The Impact

The objective was to estimate abundance of marsh deer in the Paraná River basin of this work. The results provided information to support further analysis of the impact of the Porto Primavera flooding lake over population. Sixty-nine animals were recorded by aerial survey using distance sampling methodology. Animals were widely distributed throughout the study area. The uncorrected data resulted in a estimate density of 0.0035 ind/ha and a population size of 636 individuals. Correcting the g for the animals that could be missed the calculated abundance was 896 (CV=0.27) individuals. This methodology was applied with success to survey marsh deer. The result was important to evaluate the marsh deer status in the area, and for future analysis of the impact of the flooding dam.

scholarly journals AVALIAÇÃO DE SISTEMAS ENERGÉTICOS PARA VACAS LEITEIRAS

Nativa ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 280
Author(s):  
Graciele Fatima do Nascimento Batista ◽  
Márcia Rodrigues Carvalho Oliveira ◽  
Daiane Caroline de Moura ◽  
Jocely Gomes de Souza ◽  
Henrique Melo da Silva ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Energy Requirement ◽  
Energy Requirements ◽  
Mean Square ◽  
Tropical Condition ◽  
Accuracy And Precision ◽  
Tropical Conditions ◽  
Feeding Trials ◽  
Similar Accuracy

Objetivou-se avaliar a qualidade da predição das exigências de energia para vacas leiteiras do sistema de Oliveira (2015) para condições tropicais, em comparação aos sistemas AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2004), INRA (2007), CSIRO (2007) e Moraes et al. (2015). Utilizou-se observações de quatro experimentos de alimentação de vacas leiteiras do tipo rotativo, totalizando 181 observações de consumo de nutrientes digestíveis totais (NDT) de 16 dietas experimentais. O conjunto de dados construídos apresentou uma ampla variação nas características dos animais (produção de leite entre 6,1 a 36,5 kg/dia), dieta e consumo de NDT (4,0 a 16,6 kg/dia). O sistema energético de Oliveira (2015) explicou 83% do consumo de NDT observado, superestimou o consumo de NDT em média 0,35 kg/dia e apresentou raiz quadrada do erro médio de predição (RQEMP) de 12,2% do valor observado. Os sistemas AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2014) e Moraes et al (2015) apresentaram RQEMP similares (P > 0,05) ao sistema de Oliveira (2015), indicando similaridade na acurácia para predizer as exigências de energia para vacas leiteiras em condições tropicais. Recomenda-se ainda investigar a adequação destes sistemas energéticos em experimentos de longa duração.Palavras-chave: acurácia; energia; sistemas nutricionais. EVALUATION OF ENERGETICS SYSTEMS FOR DAIRY COWS ABSTRACT: The objective was evaluate accuracy and precision of the estimated energy requirements for lactating dairy of the Oliveira (2015) system to tropical condition, compared to AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2004), INRA (2007), CSIRO (2007) and proposed by Moraes et al. (2015). Four rotative feeding trials were used as dataset, totalizing 181 observations of total digestible nutrient (TDN) intake from 16 diets. Dataset had wide variation in animal performance (milk yield between 6.1 to 36.5 kg/day), diet and TDN intake (4.0 to 16.6 kg/day). The Oliveira (2015) system explained 83% of the observed TDN intake, over-predicted TDN intake by 0.34 kg/day and presented root mean square error of prediction (RMSPE) of the 12.2% of the observed TDN intake. AFRC (1993), NRC (2001), Feed into Milk (THOMAS, 2014) e Moraes et al (2015) systems had similar RMSPE (P > 0.05) to Oliveira (2015) system, indicating similar accuracy to predict energy requirement for dairy cows under tropical conditions. We recommended to investigate the adequacy these systems in long term feeding trials.Keywords: accuracy; energy; nutritional systems.

scholarly journals Group IV humpback whales: their status from aerial and landbased surveys off Western Australia, 2005

2020 ◽  
pp. 223-234
Author(s):  
Charles G.M. Paxton ◽  
Sharon l. Hedley ◽  
John l. Bannister
Keyword(s):  
Aerial Survey ◽  
Group Iv ◽  
Humpback Whales ◽  
Reliable Estimate ◽  
Line Transect ◽  
Absolute Abundance ◽  
Density Estimates ◽  
Abundance Estimates ◽  
Short Period ◽  
Land Station

Single platform aerial line transect and land-based surveys of Southern Hemisphere Group IV humpback whales were undertaken to provide absoluteabundance estimates of animals migrating northward along the western Australian coast during June–August 2005. The aerial survey was designedto cover the whole period of northward migration but the resulting estimates from that survey alone could only, at best, provide relative abundanceestimates as it was not possible to estimate g(0), the detection probability along the trackline, from the data. Owing to logistical constraints, theland-based survey was only possible for a much shorter period (two weeks during the expected peak of the migration in mid-July). This paperproposes three methods that utilise these complementary data in different ways to attempt to obtain absolute abundance estimates. The aerial linetransect data were used to estimate relative whale density (for each day), allowing absolute abundance from the land-based survey to be estimatedfor the short period of its duration. In turn, the land-based survey allowed estimation of g(0) for the aerial survey. Absolute estimates of abundancefor the aerial survey were obtained by combining the g(0) estimate with the relative density estimates, summing over the appropriate number ofdays. The most reliable estimate of northward migrating whales passing the land station for the period of the land-based survey only was 4,700(95% CI 2,700–14,000). The most reliable estimate for the number of whales passing through the aerial survey region for the duration of that survey(55 days from June through to August) was 10,300 (95% CI 6,700–24,500). This is a conservative estimate because the duration of the aerial surveywas almost certainly shorter than the period of the migration. Extrapolation beyond the end of this survey was considered unreliable, but abundancefrom the estimated start of the migration to the end of the survey (87 days from mid-April to August) was estimated to be 12,800 (95% CI 7,500–44,600). The estimated number of whales depends crucially on the assumed migration and period of migration. Results for different migrationparameters are also presented. The point estimates of abundance, whilst higher than those from a previous survey in 1999 (when adjusted for surveyduration) are not significantly so. The peak of the whales’ distribution was found at c.90m water depth.

An aerial survey method to estimate sea otter abundance

2021 ◽  
pp. 13-26
Author(s):  
James L. Bodkin ◽  
Mark S. Udevitz
Keyword(s):  
Aerial Survey ◽  
Survey Method ◽  
Sea Otter

Keanekaragaman Perifiton Daun Lamun Enhalus acoroides dan Cymodocea serrulata di Teluk Awur, Jepara

2021 ◽  
Vol 10 (2) ◽  
pp. 306-312
Author(s):  
Adelia Hilma Sugiarto ◽  
Raden Ario ◽  
Ita Riniatsih
Keyword(s):  
Marine Ecosystem ◽  
Survey Method ◽  
Line Transect ◽  
Cross Sectional ◽  
High Productivity ◽  
Enhalus Acoroides ◽  
Seagrass Ecosystem ◽  
Morisita Index ◽  
Cymodocea Serrulata ◽  
Seagrass Density

Ekosistem padang lamun merupakan ekosistem bahari yang memiliki keanekaragaman hayati dan memiliki produktivitas tinggi di perairan dangkal. Adanya keberadaan perifiton yang menempel pada daun lamun diduga dijadikan sebagai faktor penunjang produktivitas primer di kawasan ekosistem lamun. Penelitian ini bertujuan untuk mengetahui kelimpahan perifiton, distribusi perifiton dan hubungan kerapatan lamun terhadap kelimpahan perifiton di Perairan Teluk Awur, Jepara. Penelitian ini menggunakan metode survei dan penentuan lokasi dipilih dengan menggunakan metode sampling purposive method, sedangkan metode pengambilan data lamun mengacu pada metode line transek kuadran. Pengambilan daun lamun untuk pengamatan perifiton menggunakan metode sapuan daun yang selanjutnya diamati dengan menggunakan mikroskop. Nilai kelimpahan perifiton pada daun lamun Enhalus acoroides di Stasiun 1, Stasiun 2, dan Stasiun 3 berturut-turut adalah 105 ind/cm2, 167,5 ind/cm2, dan 101,25 ind/cm2. Sedangkan kelimpahan perifiton pada daun lamun Cymodocea serrulata di Stasiun 1 tidak ada lalu Stasiun 2 dan Stasiun 3 berturut-turut adalah 80 ind/cm2 dan 135 ind/cm2. Kelimpahan tertinggi perifiton terdapat pada jenis lamun E. acoroides diduga karena E. acoroides mempunyai luas penampang daun yang lebih lebar dibandingkan C.serrulata. Perifiton yang mendominasi di lokasi ini berasal dari Kelas Bacillariophyceae. Sebaran perifiton berdasarkan perhitungan indeks morisita yaitu berkelompok dan terdapat hubungan antara kelimpahan perifiton dengan kerapatan lamun.  The seagrass ecosystem is a marine ecosystem that has biodiversity and is high productivity in shallow waters. The presence of periphyton attached to seagrass leaves is thought to be used as a primary productivity supporting factor in the seagrass ecosystem. This research aims to determine the periphyton abundance, periphyton distribution and seagrass density relationship towards periphyton abundance in Teluk Awur, Jepara. The survey method and location determination were selected based on purposive sampling method, while the seagrass data collection method refers to the quadrant line transect method. The taking of seagrass leaf for periphyton observation used leaf drainage method was then observed using a microscope. Periphyton abundance value on seagrass leaves of Enhalus acoroides in Station 1, Station 2, and Station 3 are respectively  105 ind / cm2, 167,5 ind / cm2, and 101, 25 ind / cm2. Periphyton abundance in seagrass leaves Cymodocea serrulata in Station 1 was not found while Station 2 and Station 3 are 80 ind / cm2 and 135 ind / cm2 respectively. The highest abundance of periphyton is in the type of seagrass E. acoroides because E. acoroides has a wider leaf cross-sectional area than C. serrulata. Periphyton that dominates the waters of Teluk Awur comes from the Bacillariophyceae class. Periphyton distribution based on the morisita index calculation is clustered and there is a relationship between periphyton abundance and seagrass density.

A comparison of unmanned aerial vehicles (drones) and manned helicopters for monitoring macropod populations

2018 ◽  
Vol 45 (7) ◽  
pp. 586 ◽  
Author(s):  
Matthew Gentle ◽  
Neal Finch ◽  
James Speed ◽  
Anthony Pople
Keyword(s):  
Data Processing ◽  
Long Range ◽  
Best Practice ◽  
Aerial Survey ◽  
Landscape Scale ◽  
Encounter Rate ◽  
Line Transect ◽  
Unmanned Aerial Systems ◽  
Survey Technique ◽  
Helicopter Survey

Context Developments in the use of remote aircraft, or unmanned aerial systems (UAS), for ecological study have been rapid. Helicopter surveys have proven to be a reliable, repeatable method for broad-scale monitoring of harvested kangaroo populations in Australia’s rangelands, but the recent availability of long-range UAS may offer improvements in detectability and cost efficiency. Aims We aimed to test the ability of a long-range UAS (Spylite, Bluebird Aero Systems Ltd, Kadima, Israel) to survey macropod populations at a landscape scale, and validate the results against those from the current best-practice helicopter surveys. Methods Four 80-km transects in south-western Queensland were surveyed using a helicopter and UAS. Two observers, occupying the rear seats of the helicopter, recorded animals observed in distance classes perpendicular to either side of the aircraft. Continuous electro-optical (EO) or infrared (IR) video from the UAS were recorded for later processing. Animal densities were calculated using line-transect methods for both techniques. The efficiency and cost effectiveness of each survey technique were also assessed using the flight and data processing times. Key results The encounter rate for macropods during the UAS was significantly lower compared with the helicopter survey, resulting in low estimates of macropod density (3.2 versus 53.8 animals km–2 respectively). The UAS technique recorded between 2.9 and 12.7% of the macropod density observed on each transect during the helicopter survey. The helicopter surveys were less expensive and more efficient and cost effective, requiring less flight and data processing time than the UAS surveys. Conclusions Utilising long-range UAS to detect and count groups of wild animals for landscape-scale wildlife monitoring has potential, but improvements in detection and identification technology are needed to match or exceed the accuracy of the conventional aerial survey technique for kangaroos. Implications Recent advances in camera technology and methodological refinements are encouraging for aerial survey of wildlife using UAS. However, significant improvements are required to survey for kangaroos and new technology should again be tested against current benchmarks.

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