Population Viability of Avian Endangered Species: the PVAvES Program

This report presents version 1.0 of the Population Viability for Avian Endangered Species (PVAvES) computer model. The program is designed to assess the viability of endangered bird species populations on U.S. Army lands. It also facilitates the comparison of alternative ecological scenarios based on different assumptions about the effects of natural or human (military) activities. The primary algorithms used in PVAvES are described. The model is used to assess the viability of the Red-cockaded Woodpecker (RCW) Picoides borealis, population at Fort Stewart, GA. The results showed that extinction risks were significantly underestimated, and prospects for achievement of long-term population goals were significantly overestimated, if hurricane catastrophes were not included in the population viability model. This suggests that the effects of hurricanes should not be ignored in future population viability analysis of coastal RCW populations. Some potential uses of PVAvES include estimating population viability effects of: (1) ecological catastrophes, (2) long-term (chronic) ecological disturbance of survival and/or reproduction rates, (3) changes in population carrying capacity regenerates after disturbance, (4) population supplementation through translocation, or (5) population losses due to "take." Some limitations of the model are discussed.