scholarly journals Pilot aerial study of the marine megafauna in northern coast Alagoas, Brazil

2013 ◽  
Vol 41 (1-2) ◽  
Author(s):  
Maria Danise de Oliveira ALVES ◽  
João Carlos Gomes BORGES ◽  
Maria Elisabeth De ARAÚJO
Keyword(s):  
Sea Turtles ◽  
Water Clarity ◽  
Aerial Survey ◽  
Northern Coast ◽  
Sampling Area ◽  
Turbid Waters ◽  
Aerial Surveys ◽  
Low Visibility ◽  
Marine Megafauna ◽  
Strip Transect

This study aimed to investigate the feasibility of strip-transect aerial survey for the study of the marine megafauna in northern coast of Alagoas, chosen as the pilot area due to the better water clarity and the occurrence of the Antillean manatee. It was sighted 15 dolphins, 13 sea turtles and 10 manatees. From five aspects tested on the experimental flight, three adjustments were necessary on the methodology as following: 1) reduction of the transect angle to 40º to increase the sampling area; 2) constant transects of 1.5 nautical miles from shore to standardize the area of coverage; and 3) transects restricted to the mouths of estuaries due to low visibility in turbid waters. This study demonstrated the effectiveness of aerial surveys for the detection of marine megafauna. However, the adjustments proposed are necessary to minimize the characteristic limitations of each species and/or habitat. Keywords: aerial method, manatees, dolphins, sea turtles, limitations

Aerial survey of the dugong (Dugong dugon Muller 1776) in coastal waters of the Lease Islands, East Inodonesia

1995 ◽  
Vol 46 (4) ◽  
pp. 759 ◽  
Author(s):  
HH de Iongh ◽  
R Wenno ◽  
B Bierhuizen ◽  
B van Orden
Keyword(s):  
Coastal Waters ◽  
Aerial Survey ◽  
Neonatal Calf ◽  
Aerial Surveys ◽  
Coastal Shelf ◽  
Strip Transect

During December 1990 and August 1992, aerial surveys of dugongs were made along the coastlines of the Lease Islands in East Indonesia. The aerial surveys followed a strip transect covering the coastal shelf and totalled 3.5 h of observation. During the first survey, 17 dugongs were observed, one of which was a neonatal calf; during the second survey, 10 dugongs were seen but no neonates. The minimum population of dugongs was estimated to be between 22 and 37 animals. The population probably interacts with a larger unidentified reservoir of dugongs in the coastal waters of nearby Seram and Buru Islands.

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.

scholarly journals Incorporating Geographical Scale and Multiple Environmental Factors to Delineate the Breeding Distribution of Sea Turtles

Drones ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 142
Author(s):  
Liam C. Dickson ◽  
Kostas A. Katselidis ◽  
Christophe Eizaguirre ◽  
Gail Schofield
Keyword(s):  
Sea Turtles ◽  
Regional Distribution ◽  
Environmental Parameters ◽  
Environmental Data ◽  
Offshore Wind ◽  
Loggerhead Sea Turtles ◽  
Change Models ◽  
Terrestrial Environments ◽  
Aircraft System ◽  
Marine Megafauna

Temperature is often used to infer how climate influences wildlife distributions; yet, other parameters also contribute, separately and combined, with effects varying across geographical scales. Here, we used an unoccupied aircraft system to explore how environmental parameters affect the regional distribution of the terrestrial and marine breeding habitats of threatened loggerhead sea turtles (Caretta caretta). Surveys spanned four years and ~620 km coastline of western Greece, encompassing low (<10 nests/km) to high (100–500 nests/km) density nesting areas. We recorded 2395 tracks left by turtles on beaches and 1928 turtles occupying waters adjacent to these beaches. Variation in beach track and inwater turtle densities was explained by temperature, offshore prevailing wind, and physical marine and terrestrial factors combined. The highest beach-track densities (400 tracks/km) occurred on beaches with steep slopes and higher sand temperatures, sheltered from prevailing offshore winds. The highest inwater turtle densities (270 turtles/km) occurred over submerged sandbanks, with warmer sea temperatures associated with offshore wind. Most turtles (90%) occurred over nearshore submerged sandbanks within 10 km of beaches supporting the highest track densities, showing the strong linkage between optimal marine and terrestrial environments for breeding. Our findings demonstrate the utility of UASs in surveying marine megafauna and environmental data at large scales and the importance of integrating multiple factors in climate change models to predict species distributions.

Low Visibility Formation and Forecasting on the Northern Coast of Brazil

2012 ◽  
Vol 170 (4) ◽  
pp. 689-709 ◽  
Author(s):  
Natalia Fedorova ◽  
Vladimir Levit ◽  
Aliton Oliveira da Silva ◽  
Deydila Michele Bonfim dos Santos
Keyword(s):  
Northern Coast ◽  
Low Visibility

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.

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.

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