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for illustration, that the region is as given in Table 13.1, and that this region of A=144 km^2 is to be sampled by n=4 transect ...
Its 95% confidence limits are calculated as Amultiplied by the 95% confidence limits ofD: ± 144 ×1.37 =± 197 We can check that a ...
The probability-proportional-to-size (PPS) estimate By the previous two methods all sampling units in the frame have an equal ch ...
the shape of the curve must be assumed to some extent and the validity of the assump- tion determines the accuracy of the method ...
line censuses. In particular, it is most useful for rare observations, although it does require at least 30 records to be reliab ...
standard error is the square root of the sum of the variances of the contributing stratal estimates. The variance of an estimate ...
or by different methods. A quick and dirty comparison is provided by the normal approximation, which is adequate if each survey ...
This section outlines some of the methods available for calculating the size of a population by techniques that do not necessari ...
removed or added Cxx-individuals (additions are positive, removals negative) and Cyy-individuals: C=Cx+Cy. The size of the popul ...
These formulae are for “direct sampling,” when the number of animals to be recap- tured is not decided upon before recapturing. ...
3 marked and unmarked animals die or leave the area at the same rate; 4 no marks are lost. Assumption (2) is not needed when mar ...
most studies Yitself is meaningless because the “population” is not a population in the biological sense but the animals living ...
Two counts Caughley (1974) showed that if the counts of two observers of equivalent efficiency were divided into those animals ( ...
in tandem on one side of an aircraft. Their counts of S 1 =7, S 2 =3, and B=10 yielded P 1 =0.77 and P 2 =0.59, the population e ...
squirrel populations (van Horne et al. 1997), and call counts for mourning dove (Zenaida macroura) densities (Sauer et al. 1994) ...
Errors in indices can be estimated by comparing results with a known population similar to the way we estimate bias errors in co ...
14 Age and stage structure All wildlife populations have individuals of different ages. The vital rates (i.e. birth rates and pr ...
and so forth for the other age groups 2 and 3. This would obviously be rather cum- bersome to calculate by hand for very long. F ...
converge on a stable age distribution, as illustrated in Fig. 14.2. Each age-specific proportionWx,tis given by: Wx,t= So, over ...
Wraw=eigenvec(A, 1.36) It is easier to interpret these values if we transform them into proportions: In other words, once the ra ...
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