Simple Count-Based PVA

Please read the Introduction before using the Eco-Tool, paying special attention to the the assumptions of simple count-based PVA.

Input

Enter or browse to the location of a tab-delimited text file containing two columns. The first column is time, and the second column is population size. Time points need not be equally spaced, as we are using the method of Dennis et al. 1991.

Use my data:

Use Yellowstone grizzly bear data from Eberhardt et al. 1986, Haroldson 1999, and Morris & Doak 2002.

Use North Carolina red-cockaded woodpecker data, courtesy of J. Walters and J. Hardesty (also used in Morris & Doak 2002).

Use Florida red-cockaded woodpecker data, courtesy of J. Walters and J. Hardesty (also used in Morris & Doak 2002).

   Population threshold for “quasi-extinction.”

   Maximum time into the future for which to calculate probability of extinction (time is taken from the end of the input data, in the same units as the data).

%   Percent confidence intervals for probability of extinction (e.g., 95%).

   Number of bootstrap replicates to use.

Test for outliers in population changes using DFFITS  Studentized residuals (see Morris and Doak 2002, pp. 74–76).

Remove outliers prior to analysis? No  Yes.  
(It is recommended that you select “no” initially. The possible existence of outliers will be tested for and displayed in the output. You can then decide whether to run the model again with the outliers removed.)

References

Dennis, B., P. L. Munholland and J. M. Scott (1991) Estimation of growth and extinction parameters for endangered species. Ecological Monographs 61: 115–143.

Morris, W. F. and D. F. Doak (2002) Quantitative Conservation Biology: Theory and Practice of Population Viability Analysis. Sinauer, MA.