A Practical Model of Bicknell's Thrush Habitat in the Northeastern United States
Lambert JD, Rimmer CC, McFarland KP, Faccio SD, Atwood JL. A Practical Model of Bicknell's Thrush Habitat in the Northeastern United States. Northeastern United States
Bicicnell's Thrush (Catharus bicknelli) is a rare habitat specialist that breeds in dense balsam fir (Abies balsamea) and red spruce (Picea rubens) forests at high elevations in the northeastern United States Ongoing and projected loss of this forest type has led to increased demand for information on the availability of suitable habitat. We used elevation, latitude, and forest type to construct a model of Bicknell's Thrush habitat. The model predicted the species to be present in conifer-dominated forests above an elevation threshold that descends with an increase in latitude. The slope of the threshold (-84.5 in/1 0 latitude) reflects climatic effects on forest composition and structure. To test model performance, we conducted point count and playback surveys along 1-km routes established in conifer forests above and below the threshold. The model performed at a significant level (P < 0.01), accurately predicting the status of the species on 64 of 76 (84.2%) routes. When sites within 50 vertical meters of the threshold were excluded, accuracy improved to 94.2%. This habitat model is a practical tool for conservation planning at local and regional levels.