Correcting Bias in Aerial Survey Population Estimates of Feral Livestock in Northern Australia Using the Double-Count Technique

1989 ◽  
Vol 26 (3) ◽  
pp. 925 ◽  
Author(s):  
P. Bayliss ◽  
K. M. Yeomans
Keyword(s):  
Aerial Survey ◽  
Population Estimates ◽  
Northern Australia ◽  
Survey Population

Accuracy of Pup Classifications and Its Effect on Population Estimates in the Hooded Seal (Cystophora cristata)

1988 ◽  
Vol 45 (4) ◽  
pp. 715-719 ◽  
Author(s):  
G. B. Stenson ◽  
R. A. Myers
Keyword(s):  
Developmental Stages ◽  
Survey Design ◽  
Aerial Survey ◽  
Similar Proportion ◽  
Population Estimates ◽  
Hooded Seal ◽  
Cystophora Cristata ◽  
Current Survey ◽  
Survey Estimates ◽  
Misclassification Rates

Information from the classification of age-specific developmental stages has been used to adjust aerial survey estimates of pup production in a number of species of seals, including the hooded seal (Cystophora cristata). We test the assumption that hooded seal pups were accurately and consistently classified according to developmental stage and examine the consequences of misclassifications upon adjusted population estimates. We determined overall misclassification rates, the effect of survey height on classifications, and interobserver variability. At ice level, misclassifications rates were low (<3%). From an altitude of 30 m, newborn pups could not be classified correctly and misclassification rates for the two other stages of attended pups varied between 6.4 and 21.3%. There was no evidence of an overall bias in classifications or differences among observers although there was a significant interaction between day and stage. Individual pups appear to have been misclassified independently by each observer. Under actual survey conditions, observers classified a similar proportion of pups into each recognizable stage. The misclassification rates we observed did not significantly alter the previous population estimate. Methods for improving the current survey design include modifying classification criteria, providing observers with a period of on-ice training, and reducing the width of survey transects.

Bait preference for remote camera trap studies of the endangered northern quoll (Dasyurus hallucatus)

2017 ◽  
Vol 39 (1) ◽  
pp. 72 ◽  
Author(s):  
Caitlin Austin ◽  
Katherine Tuft ◽  
Daniel Ramp ◽  
Teigan Cremona ◽  
Jonathan K. Webb
Keyword(s):  
Peanut Butter ◽  
Camera Traps ◽  
Livestock Grazing ◽  
Population Estimates ◽  
Northern Australia ◽  
Cane Toad ◽  
Live Trapping ◽  
Remote Camera ◽  
Reliable Methods ◽  
Better Than

Estimating population size is crucial for managing populations of threatened species. In the Top End of northern Australia, populations of northern quolls (Dasyurus hallucatus), already affected by livestock grazing, inappropriate burning regimes and predation, have collapsed following the spread of the toxic cane toad (Rhinella marina). Cane toads are currently invading the Kimberley, where they pose a threat to quoll populations. To manage these populations, we need reliable methods for detecting and estimating quoll abundance. We deployed camera traps with lures containing tuna, peanut butter or no bait and found that baited cameras performed better than the unbaited control. Cameras with a tuna lure detected more individuals than cameras baited with peanut butter or no bait. Cameras with a tuna lure yielded more photographs per quoll than those baited with peanut butter or no bait. We identified individual quolls from unique spot patterns and found multiple photographs improved the accuracy of identification. We also found that population estimates for the sample area derived from camera trapping were consistent with those from live trapping using mark–recapture techniques.

Distribution and Abundance of Feral Livestock in the 'Top End' of the Northern Territory (1985-86), and Their Relation to Population Control.

1989 ◽  
Vol 16 (6) ◽  
pp. 651 ◽  
Author(s):  
P Bayliss ◽  
P Bayliss ◽  
KM Yeomans ◽  
KM Yeomans
Keyword(s):  
Population Control ◽  
Sampling Rate ◽  
Aerial Survey ◽  
Northern Territory ◽  
Population Estimates ◽  
Correction Factors ◽  
Coastal Lowland ◽  
Domestic Livestock ◽  
The Mean ◽  
Over The Top

Feral and domestic livestock (buffalo, cattle, horses and donkeys) were censused by fixed-wing aerial survey over the 'Top End' of the Northern Territory (above the 16th parallel) in March-April 1985, encompassing 233 672 km2 (16.7% of the Territory). The mean sampling rate on the major coastal lowland (38 281 km2) was 7.3%, and that for the rest was 3.7%. The accuracy of population estimates was improved by applying habitat-specific visibility correction factors to animals counted in groups.

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.

An Aerial Survey of Potential Nesting Areas of the Saltwater Crocodile, Crocodylus porosus Schneider, on the North Coast of Arnehem Land, Northern Australia

1978 ◽  
Vol 5 (3) ◽  
pp. 401 ◽  
Author(s):  
WE Magnusson ◽  
GC Grigg ◽  
JA Taylor
Keyword(s):  
Coastal Wetlands ◽  
Aerial Survey ◽  
North Coast ◽  
Northern Australia ◽  
National Library ◽  
The North ◽  
Arnhem Land ◽  
Saltwater Crocodile ◽  
Different Types ◽  
Crocodylus Porosus

Results of a study of habitats used by C, povosus for nesting on the Liverpool and Tomkinson Rivers, Arnhem Land, northern Australia, are presented. These were used as the basis of an aerial survey for potential crocodile nesting habitat in coastal wetlands between Smith Point (Cobourg Peninsula) and Gove. General conclusions of the survey are given, and areas in which different types of management could be applied are indicated. Detailed results are lodged with the Australian National Library,Canberra (catalogue No. MS5640).

Net migration estimates for Greece by age, sex and citizenship, 1991-2001

2008 ◽  
Vol 5 (2) ◽  
pp. 189-202
Author(s):  
Cleon Tsimbos
Keyword(s):  
Reproductive Age ◽  
Population Estimates ◽  
Demographic Analysis ◽  
Resident Population ◽  
Net Migration ◽  
Intercensal Period ◽  
Working Age ◽  
Official Data ◽  
Migration Component ◽  
Of Greece

This paper applies techniques of demographic analysis to official data of Greece to obtain net migration estimates by age, sex and citizenship for the intercensal period 1991-2001. It is found that the overall net immigration rate for the decade is 6.3 per 100 resident population and the contribution of foreign immigrants to this figure is 88.2 per cent. 85.4 % of the net immigrants are of working age and 70.3 % of net immigrant women are of reproductive age. The results of the study can be used to formulate assumptions regarding the migration component when handling population estimates and projections.

Distribution, seasonal movements and habitat utilisation of an endangered shark, Glyphis glyphis, from northern Australia

2017 ◽  
Vol 573 ◽  
pp. 203-213 ◽  
Author(s):  
BJ Lyon ◽  
RG Dwyer ◽  
RD Pillans ◽  
HA Campbell ◽  
CE Franklin
Keyword(s):  
Northern Australia ◽  
Seasonal Movements

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

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