Estimating seabird densities from vessel transects: distance sampling and implications for strip transects
نویسندگان
چکیده
منابع مشابه
Optimizing the Width of Strip Transects for Seabird Surveys from Vessels of Opportunity
Marine bird at-sea distributions are surveyed using two standardized population surveying techniques: line transects and strip transects (Buckland et al. 1993). Line transects use the perpendicular distances to individual sightings to model a detection function, which quantifies the probability of observing an object given its distance from the trackline. This approach allows for speciesspecifi...
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varied from 10.7 gazelles km−2 in spring to 11.5 gazelles km−2 in autumn, with total population estimates of 803,820 (483,790–1,330,100 95% confidence interval) and 870,625 (499,432–1,491,278 95% confidence interval), respectively. Confidence limits were wide, and to obtain a coefficient of variation of 20%, transect lengths would need to be extended threeto four-fold. Until more efficient mean...
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A strip transect population density estimator and its variance are presented. These take into account stochastic survey velocity as well as stochastic swimming velocity and non-random swimming direction of the surveyed animals. The estimator is mainly of interest for surveys of animals with a directional swimming behaviour and swimming velocities similar to the survey velocity, such as those ca...
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The high spatial variability of estuaries poses a challenge for characterizing estuarine water quality. This problem was examined by conducting monthly high-resolution transects for several water quality variables (chlorophyll a, suspended particulate matter and salinity) in San Francisco Bay (California, U.S.A.). Using these data, six different ways of choosing station locations along a transe...
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Due to increasing threats facing bats, long-term monitoring protocols are needed to inform conservation strategies. Effective monitoring should be easily repeatable while capturing spatio-temporal variation. Mobile acoustic driving transect surveys ('mobile transects') have been touted as a robust, cost-effective method to monitor bats; however, it is not clear how well mobile transects represe...
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ژورنال
عنوان ژورنال: Aquatic Biology
سال: 2009
ISSN: 1864-7782,1864-7790
DOI: 10.3354/ab00112