A common theme in my lab is investigating the effects of alternative management practices or larger land use patterns on ecosystems, and we usually choose birds as model organisms that might be effective indicators of the larger ecosystem effect. Sometimes we take a community approach, but more often we choose one or several species that are representative of the ecosystem, and indeed may be found nowhere else. Examples include Bachman's Sparrow in southern pine savannas, Seaside Sparrow in salt marshes, and Black-throated Blue Warblers in deciduous forests in the southern Appalachians. Previous students have similarly examined the Prothonotary Warbler, Louisiana Waterthrush, Clapper Rail, and eastern indigo snake as indicator species.
The advantage of a population approach is that we can often do more detailed work, such as estimating productivity through finding and monitoring nests, estimating survival by assessing returns of color-banded birds, or estimating habitat use and movements through radiotelemetry. This allows us to address more complex questions about the effects of land use on birds and other organisms. These effects are often subtle (e.g., Marshall et al. 2002) and difficult to detect using only information about abundance or presence-absence of species.