| Abstract: | Population viability analysis programs are being used increasingly in research and management applications, but there has not been a systematic study of the congruence of different program predictions based on a single data set. We performed such an analysis using four population viability analysis computer programs: GAPPS, INMAT, RAMAS/AGE, and VORTEX. The standardized demographic rates used in all programs were generalized from hypothetical increasing and decreasing grizzly bear (Ursus arctos horribilis) populations. Idiosyncracies of input format for each program led to minor differences in intrinsic growth rates that translated into striking differences in estimates of extinction rates and expected population size. In contrast, the addition of demographic stochasticity, environmental stochasticity, and inbreeding costs caused only a small divergence in viability predictions. But, the addition of density dependence caused large deviations between the programs despite our best attempts to use the same density-dependent functions. Population viability programs differ in how density dependence is incorporated, and the necessary functions are difficult to parameterize accurately. Thus, we recommend that unless data clearly suggest a particular density-dependent model, predictions based on population viability analysis should include at least one scenario without density dependence. Further, we describe output metrics that may differ between programs; development of future software could benefit from standardized input and output formats across different programs. |
| Genre: | Article |
| ProdID: | 1015686 |
| Citation Author: | Mills, L. S.; Hayes, S. G.; ; Wisdom, M. J.; Citta, J.; Mattson, D. J.; Murphy, K. |
| Citation Contributing Office: | Forest and Rangeland Ecosystem Science Center |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 873 |
| Citation Issue: | 3 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Conservation Biology |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | JUN |
| Citation No Pagination: | |
| Citation Number Of Pages: | 11 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | p. 863-873 |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Factors leading to different viability predictions for a grizzly bear data set; 1996; Article; Journal; Conservation Biology; Mills, L. S.; Hayes, S. G.; ; Wisdom, M. J.; Citta, J.; Mattson, D. J.; Murphy, K. |
| Citation Start Page: | 863 |
| Citation Volume: | 10 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Factors leading to different viability predictions for a grizzly bear data set; 1996; Article; Journal; Conservation Biology; Mills, L. S.; Hayes, S. G.; ; Wisdom, M. J.; Citta, J.; Mattson, D. J.; Murphy, K. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
| Publisher: | |
