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Modeling Habitat Preferences and Constraints for the Common Loon in Northeastern North America
Citation:
KUHN, A., J. Copeland, D. E. NACCI, J. Cooley, K. Taylor, AND H. Vogel. Modeling Habitat Preferences and Constraints for the Common Loon in Northeastern North America. Presented at The Wildlife Society 16th Annual Conference, Monterey, CA, September 20 - 24, 2009.
Impact/Purpose:
The purpose of this research is to describe research methods developed to support eco-regional scale risk assessments for wildlife populations. An empirical landscape-habitat modeling approach was used to evaluate the relationship between landscape pattern and composition surrounding lakes and water quality measures associated with common loon presence and individual fitness. The habitat modeling methods and multi-scale approach developed in this research will be used to inform spatially explicit ecological risk assessment for wildlife populations exposed to chemical and non-chemical stressors such as habitat loss and degradation.
Description:
The common loon, Gavia immer, is considered an emblematic and ecologically important example of aquatic-dependent wildlife in North America. The northern breeding range of loons has contracted over the last century, presumably as a result of habitat degradation from human disturbance and lake shore development. The common loon population in northeastern North America experiences a wide range of lake-specific habitats, water quality conditions, and varying levels of human disturbance. Identifying critical habitat that supports and enhances individual fitness for loons is an important component of loon conservation management. We used an empirical landscape-habitat modeling approach to evaluate the relationship between landscape pattern and composition surrounding lakes and water quality measures associated with common loon presence and productivity. We developed a human disturbance index (HDI) for a subset of nest sites based on boating traffic, public access, distance to human structures, and percent developed shoreline. We used a multi-scale approach to evaluate the association of common loons and breeding habitat at multiple scales within three natural physiographic ecoregions of New Hampshire. These multiple scales reflect loon-specific biologically relevant extents, such as common loon territories, home ranges and lake-landscape influences. Ecoregional multi-scale models were developed and compared to single-scale models to evaluate model performance in distinguishing common loon breeding habitat. The presence of islands, lower total phosphorous, increasing lake size and elevation, decreasing developed shoreline and road density within 150 m surrounding nests, were found to be significant factors related to common loon presence and higher nest productivity. Increasing HDI values were found to have a statistically significant negative relationship with nest productivity. Based on information-theoretic statistics, multi-scale models outperformed single scale models within each of the three ecoregions. These results suggest common loons are selecting breeding habitat at multiple scales and differentially based on the varying landscape conditions loons encounter across northeastern North America.