Ecology and Demographics

Long-term Demographics of Montane Songbirds

Avian Productivity, Red Squirrels and Balsam Fir Mast – We have discovered a biennial cycle involving balsam fir cone mast, red squirrels and possibly other small mammals, and bird demographics. From 1995-2001, we annually monitored balsam fir reproduction, bird densities and reproductive success, and red squirrel densities. High cone production occurred biennially in late summer and fall of even-numbered years and was followed by immigration and breeding by White-winged Crossbills, Pine Siskins and red squirrels. Open cup-nesting birds experienced extremely low rates of nest success in summers following heavy cone mast, probably due to nest depredation by red squirrels and other small mammals, and high success following mast failures. Analysis of demographic variables indicates that our study populations are sinks in odd years, sources in even years, and barely break-even overall.

Effects of Ski Area Development

Evaluating the use of Vermont ski areas by Bicknell's Thrush: applications for Whiteface Mountain, New York.

Population Connectivity of Bicknell's Thrush

Population connectivity for migratory species describes the amount of mixing of individual populations between summer and winter areas as well as the stop-over and staging locations between them. This includes natal dispersal, which for migratory organisms results from two migratory movements – birth place to winter grounds and then back to first breeding site. An understanding of population connectivity for Nearctic-Neotropical migratory birds has implications for many aspects of biology, including ecology, evolution, conservation, and epidemiology.

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