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Experiments in Aerial Survey
Graeme Caughley, Ronald Sinclair and Donald Scott-Kemmis
The Journal of Wildlife Management
Vol. 40, No. 2 (Apr., 1976), pp. 290-300
Stable URL: http://www.jstor.org/stable/3800428
Page Count: 11
You can always find the topics here!Topics: Density estimation, Analysis of variance, Kangaroos, Area surveys, Animals, Sheep, Regression analysis, Experiment design, Simulations, Field experiments
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By use of balanced experiments amenable to analysis of variance we explored the effects of several factors on the accuracy of aerial survey estimates of animal density. Speed, height above ground, transect width, and observers had significant effects, whereas time of day, fatigue of observers, and length of survey were less important. We tested the hypothesis that a regression of observed density on speed, height, and transect width could be extrapolated backward to estimate true density at zero values of these survey variables. The results were generally consistent with this expectation. The uses of this technique are outlined, with examples, in the context of correcting an observed density to an estimate of true density, of calibrating one observer against another, and of comparing the results from aerial surveys flown at different speeds and heights, and with different widths of transect. The field experiments utilized red kangaroos (Megaleia rufa) at unknown densities and domestic sheep at known densities. Laboratory experiments were performed on dots of known density projected onto a screen. Before the model is accepted as generally applicable it must be tested against several other species in a variety of habitats.
The Journal of Wildlife Management © 1976 Wiley