A habitat and population viability analysis for potential peregrine falcon reintroductions in southern Illinois

The peregrine falcon (Falco peregrinus anatum) has not yet recolonized natural cliff sites in Illinois, remaining restricted to urban areas. I identified cliffs in southern Illinois using slope in a Digital Elevation Model, visited 38% of these cliffs, and assessed their suitability as nesting sites based on agreement with attributes reported in the literature for existing peregrine populations. Most (18 of 23) cliffs identified possessed attributes consistent with good peregrine falcon nesting sites, suggesting that slope can be used as a simple habitat predictor. Using this predictor and a density estimate of 1 pair every 10-30 km, southern Illinois should be capable of supporting 5-16 territorial pairs on 69 km of cliffs, primarily along the Mississippi and Ohio Rivers and in the Shawnee National Forest. I identified 10 possible reintroduction sites that lacked great horned owls (Bubo virginianus), a predator of young peregrines.;I constructed a habitat map for southern Illinois and the surrounding region using the slope model, and linked it with a stage-structured population matrix to analyze peregrine population viability and strategies for reintroduction. I derived habitat-specific demographic rates from the Midwest Peregrine Society Database for peregrines in the central Mississippi River region during 1982-2006. Mark-recapture analysis showed that juveniles fledged from cliffs had an annual survival rate of 20%, whereas juveniles from urban areas had an annual survival rate of 24%. Annual survival rates of subadults from cliff sites (84%) were similar to subadults from urban sites (85%) and to adults from both habitat types (85%). I also estimated average number of fledglings per pair from cliff sites (1.8 +/- 0.5) and urban sites (2.6 +/- 0.1) during 2000-2005. Results of the population viability analysis indicated that the peregrine population in the study region is not likely to go extinct and is slowly increasing. Recolonization of cliff sites in southern Illinois likely will occur via dispersal from urban populations. A cost-benefit analysis indicates that the most cost-effective reintroduction strategy would cost approximately...