Field Protocols
OVERVIEW
Conservation of biological diversity depends on identification and preservation of habitat conditions that sustain healthy populations of coexisting species. Healthy populations are those in which reproduction is sufficient to maintain population size. Breeding biology information is needed to estimate population health and predict vulnerability of species to habitat changes, but such information is lacking for most species. BBIRD monitors breeding productivity and habitat conditions of nongame birds using standardized sampling protocols across local microclimatic gradients, differing land management regimes, and broad geographical regions to allow: 1) identification of species' breeding habitat requirements, 2) assessment of current population health based on breeding productivity for a wide range of species throughout their breeding ranges, 3) early detection of population problems or benefits arising from land management programs, habitat change/fragmentation, or global warming, and 4) projection of species vulnerability to habitat disturbance and global climate change.
NEEDS ADDRESSED
Habitat conversion, land management, and possibly global climate changes are causing loss or change in available habitats. Monitoring programs based solely on censusing may only detect population problems long after they occur; unhealthy populations can be maintained by immigration from healthy populations, causing some population problems to go undetected for years. Thus, presence of a species as detected by censusing may not reflect a population's health because censusing can not detect breeding productivity problems resulting from problematic nest predation, parasitism, or disturbance.
Habitat suitability and breeding population health are best assayed by breeding productivity. Such information is critical because conservation of biodiversity requires preservation of the habitat conditions necessary for sustaining breeding productivity at levels that maintain healthy populations. Moreover, knowledge of habitat requirements allows prediction of species responses to habitat changes, differing land management programs, and global climate change, further aiding management efforts. Finally, detection of declining productivity within populations allows early implementation of management responses. Despite these critical needs, breeding productivity is not widely monitored currently. Furthermore, the specific habitat features and range of habitat conditions needed to sustain breeding productivity of entire assemblages of coexisting species are unknown. A broad-scale research and monitoring program for breeding productivity and habitat requirements of entire communities of coexisting species is needed and such data are best gathered by collaborative partnerships among independent investigators spread over a broad geographic area.
The BBIRD program was initiated to address the above needs. The program identifies habitat conditions affecting breeding productivity and population health of species throughout their geographic ranges. BBIRD also allows monitoring of changes in breeding productivity, population sizes, and availability of microhabitats used by species to provide sensitive indicators of habitat change or global warming. The program is based on partnerships and data-sharing among researchers that use standardized sampling protocols. This allows comparisons of nesting productivity and associated habitat across broad geographic regions to assess the breadth of environmental problems and provide data for implementing management responses. More than 25,000 nests were located and monitored in the first five years of the program.
Nongame birds are particularly appropriate for monitoring environmental health. 1) Breeding Bird Surveys suggest that populations of many nongame bird species are declining. 2) Bird species differ in environmental requirements and tolerances and thus form sensitive indicators of environmental health. 3) Breeding productivity is more easily monitored for birds than for any other group of vertebrate taxa. 4) Results under this program can be compared with larger regional patterns provided by other censusing programs. 5) Federal agencies have a responsibility to conserve bird populations under the Mitchell Amendment and National Forest Management Act. 6) Nongame birds are in the public eye. A 1985 survey revealed 46% of the U.S. population over 16 years of age (82.5 million people) purchase food for wild birds.
OBJECTIVES
- Monitor breeding productivity and associated habitat to determine status of population health and to provide an early warning signal of population problems.
- Provide baseline data on breeding productivity of species in healthy environments.
- Identify unhealthy habitats and conditions.
- Develop models of habitat needs for healthy populations of coexisting species.
- Use models to asses suitability of habitat conditions for sustaining bird diversity under varying land management and disturbance regimes.
- Examine microhabitat use, distributional, and demographic responses to climate differences in time and space to project long-term responses to global climate change.
- Use information to implement management solutions to maximize probability of arresting problems early and prior to their becoming irreversible or cost-prohibitive.
GENERAL APPROACH
BBIRD replicates intensive local studies at sites across North America. Each site includes randomly-located replicate plots, the size and number of which vary depending on local objectives and productivity of the habitat. Nests of all or focal bird species found within each plot are located and monitored to provide data on breeding productivity of coexisting species. Nest searching and monitoring protocols follow methods outlined in Martin and Geupel (1993). Vegetation sampling is similar to methods described by Martin and Roper (1988) and Martin (1993) with some modifications (detailed sampling methods are outlined in this publication). Point counts are used to index general differences in population size in space and time. There are two types of BBIRD sites, funded and volunteer. Funded sites follow this protocol completely. Volunteer participants obtain their own funding and use BBIRD protocols to the extent possible. The minimum requirement for participation in the program by volunteers is data on nesting productivity and sources of nesting mortality. However, measurement of vegetation associated with nest sites is also a critical element and is strongly encouraged. Point counts are included whenever possible to provide population trend information.
ORGANIZATION, STATUS, AND PUBLICATION RIGHTS
BBIRD is organized through the Division of Cooperative Research of the National Biological Survey, but depends on partnerships with other agencies. Studies at each local site are administered by an independent principal investigator to maintain high data quality. This facilitates rapid identification and publication of important results at individual local sites. Data collection began in 1992. Over 25,000 nests were monitored in 21 states and Puerto Rico from 1992-1996. Studies in more sites are needed and are being added to expand coverage and scope of inference. Data from all sites are merged and maintained in a central repository at the Montana Cooperative Wildlife Research Unit to allow overview analyses of trends and patterns across sites and to allow individual investigators to query the database to compare their results with other sites. All groups participating in the effort and providing data can request any portions of the shared data set for analyses. Requests will be fulfilled provided they do not conflict with goals and objectives of investigators supplying the data. Any requests for data gathered within 5 years of the request will be checked with individual investigators to ensure first rights of publication. When the majority of data being used in an analysis are from a single investigator's site, that investigator will be expected to be invited to serve as a coauthor on the publication. All publications resulting from this program should acknowledge BBIRD and send 2 reprints to the central site (Montana).
PRODUCT DEVELOPMENT
BBIRD will identify population health and habitat requirements for a wide range of species. Continued work over the long-term (15-20 years) and continued program expansion will allow more complete examination of habitat requirements and responses to land conversion processes and climate changes. These data can also be used to potentially tie in with other GIS programs and other monitoring programs to refine products of these programs.
For information contact: Thomas E. Martin, Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT 59812; (406)-243-5372; tmartin@selway.umt.edu.
Field Protocols
Last modified: Sunday, 23-March-97 12:08:47 MST