4. Section Overview—Population and Habitat Assessment:
Monitoring Bird Populations Over
Large Areas
John R. Sauer
Robert J. Cooper
Monitoring provides essential information about status
and change in bird populations. For Neotropical migrant
birds (NTMBs), the North American Breeding Bird Survey
(BBS) has been particularly influential in documenting
regional population change (e.g., Robbins and others 1989b),
and often is cited as justification for management actions.
However, as with most bird surveys, the design of the BBS,
and the geographic scale of the information, often limits its
use either in evaluating the response of bird populations to
management, or in identifying causes of population change.
In the study of NTMB population change, limitations of
the landscape-scale BBS data are all too apparent. Adequately documenting patterns of change in populations
using survey data is often difficult due to controversy about
methods and limitations of the count-based survey design
(e.g., Böhning-Gaese and others 1993; James and others
1995; Sauer and others 1996a; Link and Sauer 1997). Also,
analyses of population change from the BBS often end with
frustrating statements about the survey’s inability to establish causes of population change (e.g., Peterjohn and others
1995), clearly emphasizing the lack of linkages of the
data collection to management. Many monitoring programs (1) are too poorly designed to allow us to adequately
evaluate population change; (2) provide data collected at the
wrong scale for appropriate management; and (3) are difficult to interpret unless their data are collected in a specific
management context, for example, in conjunction with an
experimental design or adaptive management. Developing
additional monitoring programs, and fitting BBS information into management contexts, will improve our ability to
understand bird population dynamics. The collection of
monitoring papers in this volume outline some innovative
approaches to gathering information using designs and
scales appropriate for management.
Design of surveys, and connecting survey design to management objectives, is the primary concern of several of the
papers. Johnson discusses some of the challenges associated
with developing a local or regional monitoring program.
Often, if objectives are not well defined before the survey is
initiated, the results will not be useful for any objective.
In: Bonney, Rick; Pashley, David N.; Cooper, Robert J.; Niles, Larry,
eds. 2000. Strategies for bird conservation: The Partners in Flight planning process; Proceedings of the 3rd Partners in Flight Workshop; 1995
October 1-5; Cape May, NJ. Proceedings RMRS-P-16. Ogden, UT: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research
Station.
John R. Sauer, Patuxent Wildlife Research Center, 11510 American Holly
Drive, Laurel, MD 20708. Robert J. Cooper, Warnell School of Forest Resources, University of Georgia, Athens, GA 30602.
USDA Forest Service Proceedings RMRS-P-16. 2000
Methods need to be chosen appropriate to the stated objectives, and principles of experimental design must be followed if monitoring is to be used to assess the consequences
of management activities. Nichols suggests that retrospective studies based on monitoring results often do not lead to
“reliable knowledge.” Instead, monitoring is most useful
when incorporated into experimentation or adaptive management, in that it then allows us to evaluate population
responses to management actions. Often, management for
birds involves habitat management, and Twedt and Loesch
advocate habitat monitoring using Geographic Information
Systems as an essential element of bird conservation planning. Evans and Rosenberg describe their efforts to develop
acoustic monitoring programs, and document some initial
successes of the procedure.
Scale-specific monitoring and integration of monitoring
programs is addressed by several papers. Sauer uses information from the BBS to argue that monitoring data often do
not interpolate from regional to local scales, and that management needs at each scale require scale-specific monitoring. Sauer, Hadidian, Droege, Handly, Williams, Swarth,
Didden, and Huff describe a monitoring program for birds in
urban environments of Washington, DC. Urban areas are
generally not well monitored by the BBS, but data from
these areas often play an important role in defining public
and scientific perceptions of bird population change. Hamel,
Brunswig, Dawson, and Staten review several case studies
of monitoring at local and regional scales, documenting the
benefits of several programs in the southeastern United
States. Downes describes the Canadian Landbird Monitoring Strategy, which is designed to provide information on
status and trends of bird populations for species and geographic scales of management interest. The Strategy extends beyond counting birds, to include monitoring demographic parameters such as survival and productivity,
monitoring habitats along with count data from the BBS,
and information transfer and educational activities associated with bird monitoring. Handel describes regional research and monitoring for landbirds in Alaska, with the goal
of combining count data and demographic data to develop a
comprehensive monitoring program within logistical and
physical constraints imposed by the large area of interest
and limited access by roads. A variety of research and
management questions were specified, and monitoring at
several geographic scales has been implemented to provide
information to address the questions.
These papers indicate a clear advance in monitoring. Rather
than simply documenting population change using methods
with unknown sampling properties, the authors suggest that
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reliable information can be derived only from sampling with
well defined goals, statistically valid sampling methods, and
with a clear experimental or adaptive management context.
They also express the need for scale-specific information, and
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information on demography rather than just counts of
birds. Following these recommendations should result in
clarification of the causes of population changes in landbird
populations.
USDA Forest Service Proceedings RMRS-P-16. 2000