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Modeling Habitat Associations for the Common Loon (Gavia immer) at Multiple Scales in Northeastern North America
Citation:
KUHN, A., J. Copeland, J. Cooley, H. Vogel, K. Taylor, D. E. NACCI, AND P. August. Modeling Habitat Associations for the Common Loon (Gavia immer) at Multiple Scales in Northeastern North America . Avian Conservation and Ecology. Society of Canadian Ornithologists and Bird Studies Canada, , Canada, 6(1):4, (2011).
Impact/Purpose:
Wildlife populations are experiencing increasing pressure from human-induced changes in the landscape. Stressors include agricultural, residential and urban land use, introduced invasive and exotic species, nutrient enrichment, direct human disturbance, and toxic chemicals that directly or indirectly influence the quality and quantity of habitat used by terrestrial and aquatic wildlife. Governmental agencies such as the U.S. Environmental Protection Agency are required to assess risks to wildlife populations that result from these multiple stressors, yet considerable uncertainty exists with respect to how such assessments should be conducted. The mandates of the Clean Water Act dictate the need to develop processes for ecological protection that reflect greater biological and environmental complexity and realism. Thus, EPA is required to develop methods to assess and predict effects of multiple stressors on wildlife populations and to develop criteria protective of those populations. Chemical exposures often co-occur with non-chemical stressors associated with human activities, frequently resulting in habitat alteration and loss. This research addresses a number of these issues, specifically issues of scale and the effects of chemical and non-chemical stressors such as habitat degradation and loss on wildlife species within a landscape context. This research describes an empirical approach to assess the effects of multiple stressors at multiple scales for wildlife species to support the development of protective criteria and improve wildlife risk assessments.
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 Common Loons has contracted over the last century, presumably as a result of habitat degradation from human disturbance and lake shore development. Our research focused on a geographic area, the state of New Hampshire, USA, where a long-term monitoring program conducted by the Loon Preservation Committee has been collecting biological data on Common Loons since 1976. The Common Loon population in New Hampshire is distributed throughout the state and experiences a wide range of lake-specific habitats, water quality conditions, and varying levels of human disturbance. We used a multi-scale approach to evaluate the association of Common Loons and breeding habitat 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. Based on information-theoretic statistics, multi-scale models outperformed single scale models within each of the three ecoregions. Our results suggest that the Common Loon is responding to both ecological and anthropogenic factors at multiple scales when selecting breeding sites. These multi-scale models can be used to identify and prioritize the conservation of preferred nesting habitat for Common Loon populations.