Estimating kangaroo density by aerial survey: a comparison of thermal cameras with human observers

2019 ◽  
Vol 46 (8) ◽  
pp. 639 ◽  
Author(s):  
Mark Lethbridge ◽  
Michael Stead ◽  
Cameron Wells
Keyword(s):  
Thermal Imaging ◽  
Imaging Techniques ◽  
Population Data ◽  
Aerial Survey ◽  
Time Of Day ◽  
Human Observer ◽  
Thermal Camera ◽  
Density Estimates ◽  
Aerial Surveys ◽  
Animal Populations

Abstract ContextAerial surveys provide valuable information about the population status and distribution of many native and pest vertebrate species. They are vital for evidence-based monitoring, budget planning and setting management targets. Despite aircraft running costs, they remain one of the most cost-effective ways to capture distribution and abundance data over a broad area. In Australia, annual surveys of large macropods are undertaken in several states to inform management, and in some jurisdictions, to help set commercial kangaroo harvest quotas. Improvements in the cost efficiencies of these surveys are continually sought. Aerial thermal imaging techniques are increasingly being tested for wildlife surveys, but to date no studies have directly compared population data derived from thermal imaging with data collected by human observers during the same flight. AimsDuring an aerial survey of western grey kangaroos (Macropus fuliginosus), eastern grey kangaroos (M. giganteus) and red kangaroos (Osphranter rufus) across the state of Victoria, Australia, the objective was to conduct a direct comparison of the effectiveness of thermal camera technology and human observers for estimating kangaroo populations from aerial surveys. MethodsA thermal camera was mounted alongside an aerial observer on one side of the aircraft for a total of 1360km of transect lines. All thermal footage was reviewed manually. Population density estimates and distance sampling models were compared with human observer counts. Key resultsOverall, the kangaroo density estimates obtained from the thermal camera data were around 30% higher than estimates derived from aerial observer counts. This difference was greater in wooded habitats. Conversely, human-derived counts were greater in open habitats, possibly due to interference from sunlight and flushing. It was not possible to distinguish between species of macropod in the thermal imagery. ConclusionsThermal survey techniques require refining, but the results of the present study suggest that with careful selection of time of day for surveys, more accurate population estimates may be possible than with conventional aerial surveys. ImplicationsConventional aerial surveys may be underestimating animal populations in some habitats. Further studies that directly compare the performance of aerial observers and thermal imaging are required across a range of species and habitats.

Correcting for Incomplete Sighting in Aerial Surveys of Kangaroos

1986 ◽  
Vol 13 (3) ◽  
pp. 339 ◽  
Author(s):  
A Barnes ◽  
GJE Hill ◽  
GR Wilson
Keyword(s):  
Species Differences ◽  
Aerial Survey ◽  
Time Of Day ◽  
Correction Factors ◽  
Density Estimates ◽  
Mathematical Properties ◽  
Aerial Surveys ◽  
Alternative Method ◽  
Management Procedures ◽  
Continued Use

Kangaroo density estimates derived from aerial survey depend on the method of deriving sightability correction factors developed by Caughley. The method depends on five assumptions, some concerned with the mathematical properties of a model for sightability probabilities and others with deriving correction factors from this model. All these assumptions can be criticized. In addition, evidence on the performance of the method does not suggest that it is accurate. Published density estimates are less precise than indicated, and may include biases due to factors not considered in the correction factors used, e.g. seasonal conditions, time of day, and species differences. At present, no satisfactory alternative method of correction exists but, because inaccuracies may be large, continued use of the method requires much greater caution than has previously been shown. This is particularly relevant where density estimates are used to determine management procedures.

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.

Variation in harbour seal counts obtained using aerial surveys

2010 ◽  
Vol 90 (8) ◽  
pp. 1659-1666 ◽  
Author(s):  
Louise Cunningham ◽  
John M. Baxter ◽  
Ian L. Boyd
Keyword(s):  
Aerial Survey ◽  
Specific Model ◽  
Time Of Day ◽  
Harbour Seal ◽  
Survey Period ◽  
North West ◽  
Aerial Surveys ◽  
Harbour Seals ◽  
The Uk ◽  
Post Hoc

Aerial surveys of harbour seals (Phoca vitulina) are usually carried out to provide an index of population size. This can be normalized, either by design or by post-hoc analysis to reduce the effects that date, time of day, tide and weather might have on the number of seals counted. In order for long-term trends to be determined from these counts it is assumed that the mean number of seals at a particular site does not vary during the survey period, and that the start and duration of the survey window does not vary with location or between years. This study used a combination of repeat land-based and aerial surveys to test the assumption for constancy of counts during the survey period. The study focused on harbour seal abundance at haul-out sites around the Isle of Skye in north-west Scotland. The coefficient of variation in these counts was estimated to be 15%, based on repeat aerial surveys using thermal imaging. Land-based counts were used to examine the effect of covariates on seal numbers using generalized additive modelling. This site-specific model predicted that the current aerial survey window for harbour seals in the UK, which is a three-week period during the moult, is about a week too early and that count variation could be reduced by surveying 1 1/2 hours earlier in the tidal cycle. Furthermore, the pupping period showed even higher (though more variable) abundance of hauled out seals than during the moult.

A Note on the Sightability of Emus During an Aerial Survey

1988 ◽  
Vol 15 (6) ◽  
pp. 647 ◽  
Author(s):  
J Hone ◽  
J Short
Keyword(s):  
Cloud Cover ◽  
Weighted Average ◽  
Limited Range ◽  
Aerial Survey ◽  
Time Of Day ◽  
True Density ◽  
Aerial Surveys ◽  
Dromaius Novaehollandiae ◽  
Survey Estimates

Observed densities of emus, Dromaius novaehollandiae, estimated from aerial surveys were compared with results of a drive count in 1985 and 1986. The study area was mostly open shrubland. True density of emus was 2.56 per km2 in 1985 and 1.15 per km2 in 1986. Aerial survey estimates were 66 and47% oftrue density in the two years, respectively, and the weighted average was 60%. Over the limited range tested ofeach variable, observed density was not significantly affected by temperature, cloud cover or time of day.

Evaluating the use of thermal imaging cameras to monitor the endangered greater bilby at Astrebla Downs National Park

2020 ◽  
Vol 42 (3) ◽  
pp. 329
Author(s):  
John Augusteyn ◽  
Anthony Pople ◽  
Maree Rich
Keyword(s):  
Sample Size ◽  
Thermal Imaging ◽  
Detection Probability ◽  
National Park ◽  
Arid Zone ◽  
Thermal Camera ◽  
Density Estimates ◽  
Abundance Estimates ◽  
Thermal Cameras ◽  
Larger Sample

Spotlight surveys are widely used to monitor arid-zone-dwelling species such as the greater bilby (Macrotis lagotis). These surveys require a sufficient sample size to adequately model detection probability. Adequate sample sizes can be difficult to obtain for low-density populations and for species that avoid light and or have poor eyeshine like the bilby. Abundance estimates based on burrow counts can be problematic because of the variable relationship between the number of burrows used and bilby abundance. In 2013, feral predators devastated a Queensland bilby population and a method was required that could locate and monitor the remaining bilbies. We report on a study that compared density estimates derived from spotlighting and thermal cameras. Bilbies were surveyed annually over three years, using spotlights and thermal cameras on different nights but using the same transects to compare the methods. On average, thermal cameras detected twice the number of bilbies per kilometre surveyed than spotlighting. Despite this difference in the number of bilbies detected, density estimates (bilbies km−2) were similar (thermal camera versus spotlight: 0.6 versus 0.2 (2014), 3.4 versus 3.4 (2015) and 4.8 versus 3.3 (2016)). Nevertheless, the larger sample size obtained using thermal cameras gave greater confidence in modelling detection probability.

scholarly journals The potential for unmanned aerial vehicles (UAVs) to conduct marine fauna surveys in place of manned aircraft

2017 ◽  
Vol 75 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Andrew P Colefax ◽  
Paul A Butcher ◽  
Brendan P Kelaher
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Aerial Survey ◽  
Civil Aviation ◽  
Human Observer ◽  
Large Area ◽  
Marine Fauna ◽  
Survey Tool ◽  
Observer Error ◽  
Aerial Vehicles ◽  
Aerial Surveys

Abstract Unmanned aerial vehicles (UAVs) are increasingly used in marine wildlife research. As technological developments rapidly advance the versatility and functionality of affordable UAVs, their potential as a marine aerial survey tool is quickly gaining attention. Currently, there is significant interest in whether cost-effective UAVs can outperform manned aircraft in aerial surveys of marine fauna at sea, although few empirical studies have compared relative sampling efficiency, accuracy and precision. Civil aviation restrictions, and subsequent available civilian technologies, make it unlikely that UAVs will currently be more effective than manned aircraft for large area marine surveys. UAVs do, however, have the capacity to fill a niche for intensive smaller spatial scale sampling and for undertaking aerial surveys in isolated locations. Improvements in UAV sensor resolutions and alternative sensor types, such as multispectral cameras, may increase area coverage, reduce perception error, and increase water penetration for sightability. Additionally, the further development of auto-detection software will rapidly improve image processing and further reduce human observer error inherent in manned aerial surveys. As UAV technologies and associated methodology is further developed and becomes more affordable, these aircraft will be increasingly adopted as a marine aerial survey tool in place of traditional methods using manned aircraft.

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.

Evaluation of Package Defects by Thermal Imaging Techniques

2002 ◽  
Author(s):  
Yongmei Liu ◽  
Rajen Dias
Keyword(s):  
Infrared Thermography ◽  
Thermal Imaging ◽  
High Speed ◽  
Imaging Techniques ◽  
Thermal Response ◽  
Analysis Tool ◽  
Nondestructive Analysis ◽  
Ir Camera ◽  
External Heating

Abstract Study presented here has shown that Infrared thermography has the potential to be a nondestructive analysis tool for evaluating package sublayer defects. Thermal imaging is achieved by applying pulsed external heating to the package surface and monitoring the surface thermal response as a function of time with a high-speed IR camera. Since the thermal response of the surface is affected by the defects such as voids and delamination below the package surface, the technique can be used to assist package defects detection and analysis.

scholarly journals Evaluating human–coyote encounters in an urban landscape using citizen science

2020 ◽  
Author(s):  
David Drake ◽  
Shelli Dubay ◽  
Maximilian L Allen
Keyword(s):  
Citizen Science ◽  
Urban Areas ◽  
Urban Landscape ◽  
Time Of Day ◽  
Human Observer ◽  
Public Outreach ◽  
The Public ◽  
Paved Road ◽  
Almost All ◽  
Human Wildlife Conflict

Abstract Coyotes are ubiquitous in habitats across North America, including in urban areas. Reviews of human–coyote encounters are limited in scope and analysis and predominantly document encounters that tend to be negative, such as human–wildlife conflict, rather than benign experiences. The objective of our study was to use citizen science reports of human–coyote interactions entered into iNaturalist to better understand the range of first person accounts of human–coyote encounters in Madison, WI. We report 398 citizen science accounts of human–coyote encounters in the Madison area between October 2015 and March 2018. Most human–coyote encounters occurred during coyote breeding season and half of all encounters occurred in moderate development land cover. Estimated level of coyote aggressiveness varied significantly, with 90% of citizen scientists scoring estimated coyote aggression as a 0 and 7% scoring estimated aggression as a 1 on a 0–5 scale (with 0 being calm and 5 being aggressive). Our best performing model explaining the estimated distance between the human observer and a coyote (our proxy for a human–coyote encounter) included the variables distance to nearest paved road, biological season of the year relative to coyote life history, and time of day/night. We demonstrate that human–coyote interactions are regularly more benign than negative, with almost all first-hand reported human–coyote encounters being benign. We encourage public outreach focusing on practices that can foster benign encounters when educating the public to facilitate human–coyote coexistence.

scholarly journals Thermal Imaging Metrology Using High Dynamic Range Near-Infrared Photovoltaic-Mode Camera

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6151
Author(s):  
Thomas B. O. Rockett ◽  
Nicholas A. Boone ◽  
Robert D. Richards ◽  
Jon R. Willmott
Keyword(s):  
Measurement Uncertainty ◽  
Wide Temperature Range ◽  
Thermal Imaging ◽  
Near Infrared ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Thermal Camera ◽  
Temperature Range ◽  
Photovoltaic Mode ◽  
High Dynamic

The measurement of a wide temperature range in a scene requires hardware capable of high dynamic range imaging. We describe a novel near-infrared thermal imaging system operating at a wavelength of 940 nm based on a commercial photovoltaic mode high dynamic range camera and analyse its measurement uncertainty. The system is capable of measuring over an unprecedently wide temperature range; however, this comes at the cost of a reduced temperature resolution and increased uncertainty compared to a conventional CMOS camera operating in photodetective mode. Despite this, the photovoltaic mode thermal camera has an acceptable level of uncertainty for most thermal imaging applications with an NETD of 4–12 °C and a combined measurement uncertainty of approximately 1% K if a low pixel clock is used. We discuss the various sources of uncertainty and how they might be minimised to further improve the performance of the thermal camera. The thermal camera is a good choice for imaging low frame rate applications that have a wide inter-scene temperature range.

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