Paul R. Adamus, Department of Fisheries and Wildlife, Nash Hall, Oregon State University, Corvallis, OR 97330
If implemented, a continental or regional marshbird monitoring
program would serve mainly to detect temporal trends in populations of
individual species. However, with modification such a program could
also analyze spatial trends in collected data to identify areas where the
biological integrity of wetlands and their associated landscapes is being
degraded. Especially when used with data from monitoring of other
taxa, knowledge gained from a marshbird monitoring program could form a
basis for remedial action, such as selection of particular wetland sites
for restoration or implementation of watershed management plans.
Conceptually, one tool for interpreting and presenting the data
from a marshbird monitoring program might be the "Index of Biotic Integrity"
(IBI). Aquatic biologists have developed and validated IBI's regionally,
using fish and macroinvertebrates, to indicate the condition of streams
and lakes. Developing and applying wetland bird IBI's probably would
require identification of all bird species at each monitoring site, and
assignment of the species to guilds or assemblages known to be sensitive
to pollution and other human disturbance (as distinct from extreme naturally-occurring
conditions). Pilot projects in riparian habitats in Pennsylvania,
Maryland, the mid-Atlantic highlands, and the Southwest have supported
the usefulness of bird communities as indicators of landscape disturbance,
so continued development and validation of bird IBI's is warranted.
Further research should focus on (1) defining the domain of regions, landscapes,
wetland types, and disturbance types over which wetland bird IBI's can
provide accurate information on environmental impairment, (2) identifying
which wetland bird assemblages are most sensitive to human-caused disturbances,
and (3) identifying the metrics (combinations of variables) most able to
separate human-related from natural, macroscale spatial variation in bird
community structure.
Since 1996 the USEPA has sponsored a Biological Assessment of
Wetlands Work Group (BAWWG), consisting of scientists from state and federal
agencies and universities, to organize and communicate information on protocols
for monitoring and analyzing data on wetland birds, amphibians, macroinvertebrates,
algae, and plants. BAWWG has recently prepared information for state
agencies to use in developing and testing bird IBI's in wetland and riparian
habitats.