scholarly journals Application of an Ultralight Aircraft to Aerial Surveys of Kangaroos on Grazing Properties

1997 ◽  
Vol 24 (3) ◽  
pp. 359 ◽  
Author(s):  
G. C. Grigg ◽  
A. R. Pople ◽  
L. A. Beard
Keyword(s):  
Species Identification ◽  
Small Area ◽  
Aerial Survey ◽  
Accreditation Process ◽  
Line Transect ◽  
Future Scenario ◽  
Numerical Comparisons ◽  
Aerial Surveys

A Drifter ultralight aircraft was used as a platform for line-transect aerial surveys of three species of kangaroo in the sheep rangelands south-east of Blackall and north of Longreach in central-western Queensland in winter 1993 and 1994. Favourable comparisons between the results of ultralight surveys and those made from a helicopter flying the same transects and foot surveys along another set of transects, all within a few days of the ultralight survey, confirmed the expectation we had that an ultralight would be a satisfactory and much cheaper vehicle for conducting aerial surveys of kangaroos. The comparisons are even more favourable when data for the three species surveyed are combined, pointing to a problem in species identification and underlining the importance of using only experienced observers for aerial survey of kangaroos, whatever the platform. The use of an ultralight aircraft could have particular value where a comparatively small area, such as an individual sheep or cattle property, is under consideration. In this paper, we present the numerical comparisons, along with an evaluation of the practicability of using this type of aircraft. We also describe a possible future scenario in which an accreditation process could see approved kangaroo surveyors undertaking property assessments by ultralight, under contract to graziers or other interested parties.

Detectability of penguins in aerial surveys over the pack-ice off Antarctica

2008 ◽  
Vol 35 (4) ◽  
pp. 349 ◽  
Author(s):  
Colin Southwell ◽  
Charles G. M. Paxton ◽  
David L. Borchers
Keyword(s):  
Aerial Survey ◽  
Line Transect ◽  
Mark Recapture ◽  
Transect Line ◽  
Aerial Surveys ◽  
Abundance Estimates ◽  
Transect Sampling ◽  
Pack Ice ◽  
Additional Costs ◽  
Ice Floes

Knowledge of penguin abundance at regional and circumpolar scales across the Southern Ocean is important for the development of ecosystem models and to estimate prey consumption by penguins to assess potential competition with fisheries’ operations. One means of estimating penguin abundance is to undertake aerial surveys across the pack-ice surrounding Antarctica where penguins forage. However, it has long been recognised that aerial counts and resultant abundance estimates are likely to be negatively biased unless detectability is estimated and taken into account. Mark–recapture line-transect methods were used to estimate the detectability of penguin groups resting on ice floes during helicopter surveys over the pack-ice off Antarctica. Group size had the greatest effect of several measured covariates on detectability. Despite a concerted effort to meet the central assumption of conventional line-transect sampling (all objects on the transect line are detected), this was close to being achieved by single observers only in the case of the occasional very large group of >20 penguins. Emperor penguins were more detectable than Adélie penguins. Although observers undertook an extensive simulation training program before the survey, overall they improved in their ability to detect penguin groups throughout the survey. Mark–recapture line-transect methods can provide less biased estimation than conventional line-transect methods in aerial survey applications. This improvement comes with some costs, including the need for more demanding data-recording procedures and the need to use larger, more expensive aircraft. These additional costs will often be small compared with the basic cost, but the gain in terms of improved estimation may be substantial.

scholarly journals Performance of manned and unmanned aerial surveys to collect visual data and imagery for estimating arctic cetacean density and associated uncertainty

2018 ◽  
Vol 6 (3) ◽  
pp. 128-154 ◽  
Author(s):  
M.C. Ferguson ◽  
R.P. Angliss ◽  
A. Kennedy ◽  
B. Lynch ◽  
A. Willoughby ◽  
...  
Keyword(s):  
Marine Mammal ◽  
Aerial Survey ◽  
Small Sample ◽  
Unmanned Aircraft ◽  
Bowhead Whale ◽  
Line Transect ◽  
Camera System ◽  
Density Estimates ◽  
Aerial Surveys ◽  
The Cost

Manned aerial surveys have been used successfully for decades to collect data to infer cetacean distribution, density (number of whales/km2), and abundance. Unmanned aircraft systems (UAS) have potential to augment or replace some manned aerial surveys for cetaceans. We conducted a three-way comparison among visual observations made by marine mammal observers aboard a Turbo Commander aircraft; imagery autonomously collected by a Nikon D810 camera system mounted to a belly port on the Turbo Commander; and imagery collected by a similar camera system on a remotely controlled ScanEagle® UAS operated by the US Navy. Bowhead whale density estimates derived from the marine mammal observer data were higher than those from the Turbo Commander imagery; comparisons to the UAS imagery depended on survey sector and analytical method. Beluga density estimates derived from either dataset collected aboard the Turbo Commander were higher than estimates derived from the UAS imagery. Uncertainties in density estimates derived from the marine mammal observer data were lower than estimates derived from either imagery dataset due to the small sample sizes in the imagery. The visual line-transect aerial survey conducted by marine mammal observers aboard the Turbo Commander was 68.5% of the cost of the photo strip-transect survey aboard the same aircraft and 9.4% of the cost of the UAS survey.

scholarly journals The influence of animal mobility on the assumption of uniform distances in aerial line-transect surveys

2008 ◽  
Vol 35 (4) ◽  
pp. 275 ◽  
Author(s):  
Rachel M. Fewster ◽  
Colin Southwell ◽  
David L. Borchers ◽  
Stephen T. Buckland ◽  
Anthony R. Pople
Keyword(s):  
Survey Design ◽  
Distance Sampling ◽  
High Mobility ◽  
Line Transect ◽  
Transect Line ◽  
Aerial Surveys ◽  
Pack Ice ◽  
Capture Recapture ◽  
Distance Data ◽  
Crabeater Seals

Line-transect distance sampling is a widely used method for estimating animal density from aerial surveys. Analysis of line-transect distance data usually relies on a requirement that the statistical distribution of distances of animal groups from the transect line is uniform. We show that this requirement is satisfied by the survey design if all other assumptions of distance sampling hold, but it can be violated by consistent survey problems such as responsive movement of the animals towards or away from the observer. We hypothesise that problems with the uniform requirement are unlikely to be encountered for immobile taxa, but might become substantial for species of high mobility. We test evidence for non-uniformity using double-observer distance data from two aerial surveys of five species with a spectrum of mobility capabilities and tendencies. No clear evidence against uniformity was found for crabeater seals or emperor penguins on the pack-ice in East Antarctica, while minor non-uniformity consistent with responsive movement up to 30 m was found for Adelie penguins. Strong evidence of either non-uniformity or a failure of the capture–recapture validating method was found for eastern grey kangaroos and red kangaroos in Queensland.

scholarly journals Surfacing and vertical behaviour of Atlantic bluefin tuna (Thunnus thynnus) in the Mediterranean Sea: implications for aerial surveys

2020 ◽  
Vol 77 (5) ◽  
pp. 1979-1991
Author(s):  
Robert Klaus Bauer ◽  
Fabien Forget ◽  
Jean-Marc Fromentin ◽  
Manuela Capello
Keyword(s):  
Mediterranean Sea ◽  
Fork Length ◽  
Bluefin Tuna ◽  
Aerial Survey ◽  
Thunnus Thynnus ◽  
Survey Period ◽  
Atlantic Bluefin Tuna ◽  
Aerial Surveys ◽  
Gulf Of Lion ◽  
Nw Mediterranean

Abstract Atlantic bluefin tuna (Thunnus thynnus) (ABFT) frequently engage in surface basking and foraging behaviour that makes them detectable from afar. This behaviour is utilized for the development of fisheries-independent abundance indices based on aerial surveys, although changes in the surface-feeding dynamics of ABFT are not yet accounted for. We investigated the daytime surfacing behaviour of ABFT at different temporal and vertical resolutions based on 24 individuals (117–158 cm fork length), tagged with pop-up archival tags in the Gulf of Lion, NW-Mediterranean Sea between 2015 and 2016. The results suggest that ABFT remain usually <2 min continuously within the visible surface (0–1 m) during daytime. ABFT presence in the 0–1 and 0–20 m layers varied over time and between individuals but showed a seasonal decline towards autumn with the breakdown of thermal stratification. Furthermore, the rate of surfacing events was highly correlated with the time spent in the 0–20 m layer. Geolocation estimates confirm a strong site fidelity of ABFT during the aerial survey period (August–October) in the Gulf of Lion. Our results support the choice of the survey region and period, but related indices should account for the seasonality of ABFT surface behaviour [i.e. the time spent in the 0–20 m layer.

scholarly journals Boreal old-growth forest structural diversity challenges aerial photographic survey accuracy

2020 ◽  
Vol 50 (2) ◽  
pp. 155-169 ◽  
Author(s):  
Maxence Martin ◽  
Nicole J. Fenton ◽  
Hubert Morin
Keyword(s):  
Sustainable Forest Management ◽  
Forest Succession ◽  
Structural Diversity ◽  
Aerial Survey ◽  
Old Growth ◽  
Tree Species Composition ◽  
Forest Inventories ◽  
Old Growth Forest ◽  
Aerial Surveys ◽  
Old Growth Forests

The erosion of old-growth forests in boreal managed landscapes is a major issue currently faced by forest managers; however, resolving this problem requires accurate surveys. The intention of our study was to determine if historic operational aerial forest surveys accurately identified boreal old-growth forests in Quebec, Canada. We first compared stand successional stages (even-aged vs. old-growth) in two aerial surveys performed in 1968 (preindustrial aerial survey) and 2007 (modern aerial survey) on the same 2200 km2 territory. Second, we evaluated the accuracy of the modern aerial survey by comparing its results with those of 74 field plots sampled in the study territory between 2014 and 2016. The two aerial surveys differed significantly; 80.8% of the undisturbed stands that were identified as “old-growth” in the preindustrial survey were classified as “even-aged” in the modern survey, and 60% of the stands identified as “old-growth” by field sampling were also erroneously identified as “even-aged” by the modern aerial survey. The scarcity of obvious old-growth attributes in boreal old-growth forests, as well as poorly adapted modern aerial survey criteria (i.e., criteria requiring high vertical stratification and significant changes in tree species composition along forest succession), were the main factors explaining these errors. It is therefore likely that most of Quebec’s boreal old-growth forests are currently not recognized as such in forest inventories, challenging the efficacy of sustainable forest management policies.

Some human, aircraft and animal factors affecting aerial surveys: how to enumerate animals from the air

2008 ◽  
Vol 35 (4) ◽  
pp. 258 ◽  
Author(s):  
Peter J. S. Fleming ◽  
John P. Tracey
Keyword(s):  
Visual Acuity ◽  
New South ◽  
Human Memory ◽  
Aerial Survey ◽  
Factors Affecting ◽  
Counting Error ◽  
Aerial Surveys ◽  
South Wales ◽  
Survey Estimates ◽  
Aerial Platforms

Aerial surveys of wildlife involve a noisy platform carrying one or more observers moving over animals in order to quantify their abundance. This simple-sounding system encapsulates limits to human visual acuity and human concentration, visual attention, salience of target objects within the viewed scene, characteristics of survey platforms and facets of animal behaviours that affect the detection of animals by the airborne observers. These facets are too often ignored in aerial surveys, yet are inherent sources of counting error. Here we briefly review factors limiting the ability of observers to detect animals from aerial platforms in a range of sites, including characteristics of the aircraft, observers and target animals. Some of the previously uninvestigated limitations identified in the review were studied in central and western New South Wales, showing that inaccuracies of human memory and enumeration processes are sources of bias in aerial survey estimates. Standard protocols that minimise or account for the reviewed factors in aerial surveys of wildlife are recommended.

On bias, precision and accuracy in wildlife aerial surveys

2008 ◽  
Vol 35 (4) ◽  
pp. 253 ◽  
Author(s):  
Jim Hone
Keyword(s):  
Survey Data ◽  
Wildlife Management ◽  
Aerial Survey ◽  
Review Of The Literature ◽  
Density Estimates ◽  
True Value ◽  
Wildlife Population ◽  
Aerial Surveys ◽  
Precision And Accuracy ◽  
Definition Of

Bias, precision and accuracy have been studied extensively in wildlife population estimation including aerial surveys. A review of the literature shows that the concepts of bias and precision are used broadly consistently. Aerial survey data from known populations of feral pig carcases and white-tailed deer show that few density estimates are unbiased and precise. Research is needed, however, to clarify how much bias and how much precision are enough for the various types of wildlife management activities. Accuracy is used in two closely related but different ways. One set of definitions of accuracy relates to deviations from the true value (bias) and the second set relates to squared deviations from the true value (bias and precision). The implications are that authors are encouraged to clearly state which definition of accuracy they use, or focus solely on bias and precision.

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.

Calibrating Aerial Surveys of Kangaroos by Comparison With Drive Counts

1988 ◽  
Vol 15 (3) ◽  
pp. 277 ◽  
Author(s):  
J Short ◽  
J Hone
Keyword(s):  
Aerial Survey ◽  
Survey Area ◽  
Aerial Surveys ◽  
Drive Counts

Densities of red and western grey kangaroos and euros were assessed by aerial survey and compared with densities obtained in the same area by drive counts. The survey area (12.1 km2) was long, narrow and sparsely vegetated. Lakes and a kangaroo-proof fence bounded the area on three sides facilitating the drive count. Densities from aerial surveys ranged between 38 and 54% of the corresponding drive counts for red kangaroos, between 15 and 23% for western grey kangaroos, and between 9 and 10% for euros. The time of morning at which the surveys were conducted altered these percentages. About twice as many red and western grey kangaroos were counted on aerial surveys at sunrise compared to surveys 3.5 h later.

Line Transect Sampling Under Varying Conditions with Application to Aerial Surveys

Ecology ◽  
1996 ◽  
Vol 77 (4) ◽  
pp. 1297-1302 ◽  
Author(s):  
Pham X. Quang ◽  
Earl F. Becker
Keyword(s):  
Line Transect ◽  
Line Transect Sampling ◽  
Aerial Surveys ◽  
Transect Sampling
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