For the birds ...

Earth's biosphere and its biodiversity face a growing number of severe environmental threats, many of which are truly global in nature and scope. One set of threats includes climate change due to the atmospheric accumulation of greenhouse gases; loss of stratospheric ozone due to chlorofluorocarbon pollution of the atmosphere; and toxic pollution of marine, aquatic, and terrestrial ecosystems from acid rain, industrial wastes, agricultural runoff, and low-level radiation. Another set of threats includes accelerating habitat loss and degradation from the deforestation and fragmentation of tropical and temperate forest ecosystems; the desertification and conversion to development and agriculture of scrub and grassland ecosystems; the filling and development of estuarine, wetland, and riparian ecosystems; the overexploitation of marine resources; the irresponsible use of water and soil resources; and the growing urban and suburban sprawl associated with the burgeoning human population.

In some cases, the effects of these pressures on specific ecosystems and life forms are obvious and well documented. In other cases, the effects are subtle, unexpected, and undocumented and may be coupled to other processes in a synergistic manner. Either way, implementing corrective actions generally requires that environmental problems be thoroughly scientifically documented. Indeed, the human species has embarked upon a global ecological experiment, the ramifications of which may include higher extinction rates than any ever recorded in the fossil record. Long-term comprehensive biomonitoring, on a global scale, is urgently needed to effectively record the data from this experiment, and even more importantly, to point the way toward meaningful solutions.

Birds, because of their high body temperature, rapid metabolism, and high trophic position on most food webs, are excellent indicators of the effects of environmental change. Documentation of the effects of chlorinated hydrocarbon pollution on seabirds and raptors and of the effects of heavy metal accumulation on waterfowl has provided well-known examples of the value of birds as environmental indicators. Compared to other taxa, birds are relatively easily observed and counted, and they are abundant and diverse in virtually all ecosystems. Moreover, the discrete seasonality of birds' reproductive efforts makes it relatively easy to monitor their productivity, while their intermediate longevity facilitates determination of their survivorship and population age structure. Finally, the beauty of their plumage, actions, and song makes them favorite objects of human attention, study, and love.