Temperature-associated dynamics of songbird winter distributions and abundances.

Using Christmas Bird Count data, we analyze the annual spatio-temporal abundances of six passerine species in the upper Great Plains, US (1960-1990). This study provides new insight into how global warming could cause separation of species within present-day communities. We find that winter relative abundances of similarly-sized songbirds are differentially affected by ambient winter temperature.

Across space and time: social responses to large-scale biophysical systems.

The conceptual rubric of ecosystem management has been widely discussed and deliberated in conservation biology, environmental policy, and land/resource management. In this paper, I argue that two critical aspects of the ecosystem management concept require greater attention in policy and practice. First, although emphasis has been placed on the "space" of systems, the "time" -- or rates of change -- associated with biophysical and social systems has received much less consideration.

When agendas collide: human welfare and biological conservation.

Conservation should benefit ecosystems, nonhuman organisms, and current and future human beings. Nevertheless, tension among these goals engenders potential ethical conflicts: conservationists' true motivations may differ from the justifications they offer for their activities, and conservation projects have the potential to disempower and oppress people. We reviewed the promise and deficiencies of integrating social, economic, and biological concerns into conservation, focusing on research in ecosystem services and efforts in community-based conservation.

Climate and the complexity of migratory phenology: sexes, migratory distance, and arrival distributions.

The intra- and inter-season complexity of bird migration has received limited attention in climatic change research. Our phenological analysis of 22 species collected in Chicago, USA, (1979-2002) evaluates the relationship between multi-scalar climate variables and differences (1) in arrival timing between sexes, (2) in arrival distributions among species, and (3) between spring and fall migration. The early migratory period for earliest arriving species (i.

Human-modified temperatures induce species changes: Joint attribution.

Average global surface-air temperature is increasing. Contention exists over relative contributions by natural and anthropogenic forcings. Ecological studies attribute plant and animal changes to observed warming.