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.

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.

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.

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.

Aerial survey methodology and the cost of control for feral goats in Western Queensland

1998 ◽  
Vol 25 (4) ◽  
pp. 393 ◽  
Author(s):  
A. R. Pople ◽  
T. F. Clancy ◽  
J. A. Thompson ◽  
S. Boyd-Law
Keyword(s):  
National Park ◽  
Survey Methodology ◽  
Aerial Survey ◽  
Capra Hircus ◽  
Effective Control ◽  
Correction Factors ◽  
Large Area ◽  
Aerial Surveys ◽  
The Cost ◽  
Capita Cost

Feral goats (Capra hircus) were shot from a helicopter on four sites in central-western Queensland. These sites centred on Idalia National Park (660 km2) and three nearby properties: Lissoy (360 km2), Mt Calder (260 km2) and Ravensbourne (320 km2), the order reflecting increasing goat density. On Idalia, 134 goats were shot in 8 h of flying time. On Lissoy, 28 goats were shot in 3 h, 1038 goats were shot on Mt Calder in 15 h, while 2307 goats were shot on Ravensbourne in 21 h. The reduction was monitored by aerial surveys using fixed-wing aircraft. No goats were recorded on either Idalia or Lissoy immediately following shooting and substantial reductions in goat numbers were achieved on Mt Calder (75%) and Ravensbourne (49%). Surveys conducted six months after this reduction indicated population increases on all sites following shooting. This was particularly marked on Ravensbourne, where goat numbers had increased by 31% despite further substantial removals by commercial mustering. These population increases were largely the result of immigration. The cooperation of landowners over a large area is therefore essential for effective control of goats. The per capita cost of shooting goats from a helicopter was essentially constant down to a threshold density of <1 goat km-2 , below which the cost increased substantially. The accuracy of fixed-wing aerial surveys was improved by using double-counting and these corrected estimates compared favourably with index–manipulation–index estimates. Estimates of densities <1 goat km-2 were imprecise and at these densities goats were difficult to detect. The extent of vegetation cover did not affect the sightability of goats, whereas group size was positively correlated with the sightability of goats. To estimate true density, correction factors of 1–2 were applied to goat group sizes using survey parameters of 100 m strip width, a survey height of 76 m and a speed of 187 km h-1.

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.

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 Types and Frequency of Infusion Pump Alarms: Protocol for a Retrospective Data Analysis (Preprint)

2018 ◽  
Author(s):  
Kevin R Glover ◽  
Rachel R Vitoux ◽  
Catherine Schuster ◽  
Christopher R Curtin
Keyword(s):  
Data Management ◽  
Improve Patient Safety ◽  
Safety Issue ◽  
Infusion Pump ◽  
Time Of Day ◽  
Clinical Staff ◽  
Data Repository ◽  
Management Software ◽  
Alarm Fatigue ◽  
Management Procedures

BACKGROUND The variety of alarms from all types of medical devices has increased from 6 to 40 in the last three decades, with today’s most critically ill patients experiencing as many as 45 alarms per hour. Alarm fatigue has been identified as a critical safety issue for clinical staff that can lead to potentially dangerous delays or nonresponse to actionable alarms, resulting in serious patient injury and death. To date, most research on medical device alarms has focused on the nonactionable alarms of physiological monitoring devices. While there have been some reports in the literature related to drug library alerts during the infusion pump programing sequence, research related to the types and frequencies of actionable infusion pump alarms remains largely unexplored. OBJECTIVE The objectives of this study protocol are to establish baseline data related to the types and frequency of infusion pump alarms from the B. Braun Outlook 400ES Safety Infusion System with the accompanying DoseTrac Infusion Management Software. METHODS The most recent consecutive 60-day period of backup hospital data received between April 2014 and February 2017 from 32 United States-based hospitals will be selected for analysis. Microsoft SQL Server (2012 - 11.0.5343.0 X64) will be used to manage the data with unique code written to sort data and perform descriptive analyses. A validated data management methodology will be utilized to clean and analyze the data. Data management procedures will include blinding, cleaning, and review of existing infusion data within the DoseTrac Infusion Management Software databases at each hospital. Patient-identifying data will be removed prior to merging into a dedicated and secure data repository. This pooled data will then be analyzed. RESULTS This exploratory study will analyze the aggregate alarm data for each hospital by care area, drug infused, time of day, and day of week, including: overall infusion pump alarm frequency (number of alarms per active infusion), duration of alarms (average, range, median), and type and frequency of alarms distributed by care area. CONCLUSIONS Infusion pump alarm data collected and analyzed in this study will be used to help establish a baseline of infusion pump alarm types and relative frequencies. Understanding the incidences and characteristics of infusion pump alarms will result in more informed quality improvement recommendations to decrease and/or modify infusion pump alarms, and potentially reduce clinical staff alarm fatigue and improve patient safety.  REGISTERED REPORT IDENTIFIER RR1-10.2196/10446

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 &lt;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.

Sign in / Sign up

Export Citation Format

Share Document