Monitoring Landbirds in the Americas:
Written by C. John Ralph, Gregory S. Butcher,
and the members of the Working Group, February 24th, 1997
In September 1991, some 50 members of the Working Group met in Arlington, Virginia
and devised a "Needs Assessment" (Butcher et al. 1992) that set out the needs to improve the
monitoring of birds. At the onset, the needs involved three aspects: (1) the inventory of birds and
their habitats; (2) the monitoring of between year changes in bird populations; (3) and the
assessment of demographic parameters. Now, six years later, we have revisited the conclusions of
that document, and, in consultation with the members of the working group, revised and updated
the conclusions.
Much has happened since that meeting in 1991, and the members of the Working Group
can be justifiably proud of their accomplishments. As we point out below, much work is still
possible before the program reaches its full potential. We review the needs of monitoring and
inventory of landbirds, suggest the relevant literature that addresses those needs and methods, and
we suggest areas of research that might be pursued to close the gap between need and
accomplishment.
Two principal items have been adopted since the publication of the Needs Assessment.
The program now includes birds in all of the Americas, both North and South. The program also
includes all species of landbirds, both the resident species and the migratory species which link the
Americas, both symbolically and literally.
Scope of Mission of Monitoring Working Group
Partners in Flight, or Compañeros en Vuelo (PIF/CEV), is an international,
cooperative, and interactive group of biologists, organizations, agencies, countries, businesses,
and individuals interested in the broad mandate of promoting the study, information exchange,
and conservation of landbirds
throughout North and Latin America. The organization has no budget, nor a strict structure. It
relies upon cooperation and synergism to obtain its goals. The Monitoring Working Group is part
of this organization, and has been charged with devising and promoting appropriate methods for
inventory and monitoring landbirds in the Americas. Membership in the group is open to anyone
interested in its mission and who is willing to participate in its activities. Monitoring and
inventory of bird populations provides the information necessary to set priorities for conservation
and management action. Inventory is a one-time assessment of the population of the birds in an
area, while monitoring is this process continued over time, between years, as populations change.
Data taken can include population size and composition, including demographic parameters. Our
objective was to determine methods for monitoring of all species of landbirds, both migratory and
resident, in all habitats, from the arctic to the tropical rain forests. Not all methods are
appropriate in all habitats, for all densities of birds, or for all species of birds. However, the
methods that the Group has adopted are broadly applicable to most habitats and to most
species.
Monitoring of Landbirds
Several aspects were covered in the Needs Assessment, especially in relation to North
America. We describe the progress made in these areas.
- Breeding Bird Survey
The BBS of the U.S. National Biological Service provides an
excellent overview at the peak of the breeding season of the population trends of birds in Canada
and the United States. This program has expanded in the past few years, and now covers several
hundred routes. We recommend that similar programs be established in regions of Latin America,
as well on specific ownerships, such as National Parks, as an index to trends on these lands. For
maximum utility, the method requires that the same observer do the surveys in the same area on
consecutive years.
- Habitat-specific census
Establishment of a system of habitat-specific point counts was an
important priority of the Needs Assessment. This has been affirmed by the results of the
workshop on point counts (Ralph et al. 1995), that included validation of the methodology in
Latin America. Such a point count program has been initiated in some areas, such as the several
thousand point counts in an area of Colorado (Paige, pers. comm.), and some 6,000 counts over a
large area in northern California (Ralph et al.). These include only relatively small areas, and
programs have not yet been implemented in any region over a large area. This is an important
aspect of bird monitoring and should be implemented in the breeding, migration, as well as the
non-breeding seasons. Area search counts has been tested and found to be appropriate for
non-breeding monitoring.
- Migration monitoring
Marked progress has been made in the design of a system to
monitoring northern breeding species during migration, especially those species from the relatively
inaccessible boreal forests of Canada and Alaska, unmonitored by most methods. This system has
been devised by the "Migration Monitoring Council", a joint U.S. and Canada group. The
Council appointed two technical committees charged with producing documents establishing
standards and guidelines for the operation of pilot monitoring programs which can be applied
anywhere in the Americas. One committee dealt with extensive monitoring, such as checklist
programs (Dunn 1995), and the other suggested methods for intensively operated sites, such as
bird observatories and other bird capture stations (Hussell and Ralph 1995). The resulting
documents are available from the authors.
- Hawk migration
Although not landbirds, methods of monitoring of the pulse of
migration of raptors through the hemisphere uses methods that can be applied to diurnal landbird
migrants. Raptor monitoring has been boosted by the recent publication of the "Raptor Migration
Watch-site Manual" (Bildstein and Zalles 1995) (and its upcoming translation "Manual de
Observatorios de Migración de Rapaces"), and other publications, covering methods of
visual monitoring of diurnal migrants, including landbirds, as well as appropriate statistical
techniques for analysis of data.
- Including birds in contaminant monitoring
Some interest has been shown at Working
Group meetings in including birds in these monitoring programs. To date, we know of now
specific method that has been put forward.
- Validate demographic monitoring
The validation of demographic monitoring methods as
indices of reproductive and survival rates is a high priority. Without demographic information,
the discovery of a population decline in a species rarely results in any testable hypotheses. The
assessment of age ratios, recruitment, survivorship, and other demographic parameters can
suggest hypotheses and areas for investigation of population declines. Two principal methods
have been used extensively in the Americas, mist netting and nest searching. Nest searching gives
data on active nests, directly measuring the reproduction, predation, and parasitism of many
species on a local scale, as well as habitats associated with various measures. Capture by mist
nets provides systematic information on reproductive rate, survivorship, and recruitment
throughout the year. Both methods have undergone extensive and intensive evaluation by the
advocates of the methods, as well as others.
Breeding season constant-effort mist netting, under the aegis of the Monitoring Avian
Productivity and Survivorship (MAPS) program has been under review, funded by the U.S.
National Biological Service. The method was the subject of a workshop held in November 1994,
the results of which are now undergoing peer review. The advantages of this method are several,
including: (1) it covers a broad array of species, in differing scales from a few score acres to
watersheds, to (during migration) portions of the entire continent; (2) it can provide data for
breeding, migration, and non-breeding seasons. Disadvantages include (1) its usefulness is highest
where capture rates are relatively high, in habitats with low densities of birds, such as climax
forests, it provides relatively little useful data.
The program of nest monitoring is also undergoing evaluation. Advantages of the method
include: (1) it is habitat specific; (2) it provides specific information on the role of predation and
parasitism; and gives precise measures of the time in the breeding cycle when birds encounter
problems. Disadvantages of the method include (1) its use is limited to the breeding season; and
(2) it is relatively expensive.
- Analysis of banding data
It was considered important to link breeding and wintering
grounds of migrants and to determine survival rates. Progress on this issue has been slow, as the
specific benefits of such a program need to be articulated.
Monitoring Bird Habitats
The pressing need for the monitoring of habitats was recognized by the participants in the
Arlington workshop. Overall, progress has been more measured in this field, as the magnitude of
the challenge of providing a uniform method of habitat standards, criteria, and monitoring
methods has been large. A priority need is the establishment of a common method of habitat
assessment that is applicable on several scales. Given the multiplicity of potential methods,
variables to be measured, and methods of analysis, and the variety of scales, we suggest that a
workshop be convened on this subject and broad agreement reached on the most cost-effective
alternatives of habitat monitoring.
The areas of determined need include:
- Summarize known habitat requirements
The documentation of the habitat requirements
of well-known species is progressing through the various publications, such as the Birds of North
America series of the American Ornithologists' Union. However, differences in methods, the
variety of behavior components to the determination of habitat choice, as well as the intensity of
effort, promises that this goal will be an ongoing challenge over the next several years, even in
species where much research is being conducted. The methods of correlation of habitat with bird
abundance can give only partial answers, while those involving foraging substrate preferences
could well hold the key to subtleties of interactions.
- Identify unmonitored and important habitat types and their bird components
Much of the
habitats of the Americas are essentially unmonitored. Progress has been made in many areas
where priority habitats have been identified, and the birds apparently dependent upon the habitats
defined. An excellent model is provided by the Mississippi Alluvial Plain program
(Twedt et al. ms). We recommend this approach on a regional basis.
- Link bird and habitat trends
A linkage of bird populations and habitat changes (both
natural and human-caused) is dependant upon our ability to measure both components. From this
type of effort can flow management recommendations to reverse declines. An immediate
application of this would be monitoring of habitats along Breeding Bird Survey routes. This
would require a multitude of problems including a common data base, but the rewards from such
an effort would be concomitantly large.
National Programs
The various governmental agencies and organizations in each country play an
indispensable role in most monitoring efforts. The Needs Assessment addressed suggested
priorities of implementation of different levels of monitoring. It also suggested that states and
provinces be involved in these efforts.
- Funding
Basically, it was suggested that of a given agency's program, half be spent on
broad, systematic surveys, such as censuses. The remainder of funding should be split evenly
between demographic monitoring and assessment of rare habitats.
- Seasons
While breeding birds are of importance, it was suggested that migration and
non-breeding should also be a major component, as limiting habitats are not only found during the
breeding season. In fact, the stresses of migration and wintering can be a more pervasive selective
factor. In addition, the location and importance of migration stopover sites should be
assayed.
- Costs
The costs of operating various monitoring schemes is needed for guidance of
managers. Some information on this is contained in Butcher et al. (1993).
- Data Center
The need for a National Data Center in each country or region for
compilation, editing, storage, and distribution of monitoring data is still paramount to the success
of the Partners in Flight effort. No marked progress has yet been made, although in the United
States, interest on the part of the National Biological Service has increased recently. It is intended
that all participants in PIF/CEV contribute to the data bases.
International Efforts
There has been increasing awareness of the fact that PIF/CEV is a Western Hemisphere
effort, and not solely a North American effort. The concerns of the people of the Caribbean and
Latin American for their resident birds, as well as migrants, coupled with a similar concern about
resident or short-distance migrants in North America, has resulted in all landbirds being included
in the Monitoring Working Group's mandate.
- Establish communication networks
The needs throughout the Americas to coordinate
monitoring efforts, to help find funding for local scientists for training and field work, and to
promote long-term relationships between North and Latin American biologists and scientists, all
can be addressed by better communication between workers. The International Working Group,
through its newsletter La Tangara, has begun to address many of these needs. Members
of the Monitoring Working Group interested in Latin America have contributed and participated
in the newsletter and the activities of the International Working Group. The Directory of
Neotropical Ornithology (Rosenberg and Wiedenfeld 1993) is an excellent source of workers and
their projects in Latin America, as is the Ornithological Newsletter of the Ornithological Societies
of North America which is sent to all members of the participating societies.
- Coordinated Monitoring
There are two areas that need further work. These include: the
need to determine objectives and priorities of coordinated international monitoring program for
migrants and endemics; and the need for coordination and facilitation of monitoring of birds and
their habitats, including the use of remote sensing and GIS.
In part, this has been facilitated by a series of meetings in Latin America to promote these
aspects of monitoring, such as the wildlife Society Meeting in San Jose, Costa Rica (Butcher et
al. 1995, Ralph and Milá 1995), and the series of meetings sponsored by several
organizations resulting in the XXXXX (Frank Rivera), that affirmed the use of the major methods
of monitoring in Latin America, as outlined in Ralph et al. 1997. This handbook in Spanish, is a
revision and expansion of Ralph et al. (1993) that codifies the methods endorsed in the Needs
Assessment by Butcher et al. 1992, including census and demographic methods.
Ongoing Projects
Several areas of inventory and monitoring need further work.
- Protocols for other groups or species
Most species are monitored by the generally
established methods, but protocols for some specialized species, such as marsh birds, nocturnal
species, and many species in the winter, are needed. It has also been recently suggested that the
Monitoring Working Group take on standardizing protocols for monitoring shorebirds and
raptors. In past discussions over the years, it has been felt that other organizations were covering
these groups.
- Consistency of Monitoring
Many regional and state plans are being developed for
monitoring by PIF and agency personnel. While most of these plans do follow the standards and
guidelines prepared by the Group, some of these plans suggest using other methods or
approaches. It is incumbent upon the Group to review these plans and to fully communicate the
advantages and disadvantages of departures from the standardized protocols. To this end, we
plan to implement a communication network between the National, state, provincial, and regional
Monitoring Working Groups to facilitate this important communication interchange. It has been
suggested that the chairs of Regional and State Working Groups could be an ad hoc steering
committee for the National Group.
- Vegetation data
The multitude of bird monitoring methods pales before the plethora of
methods of assaying vegetation structure and composition. Providing a series of hierarchically
nested techniques for surveys in a variety of habitats will be a major challenge for the Group.
Literature Cited
Bildstein, Keith L. and Jorje I. Zalles (Eds.). 1995. Raptor migration watch-site
manual. Hawk Mountain Sanctuary Association, Kempton, Pennsylvania.
Butcher, G.S. and others. 1992. Needs Assessment: Monitoring neotropical
migratory birds. Monitoring Working Group Meeting, Arlington, Virginia, September 4 &
5, 1991. Partners in Flight, the Neotropical Migratory Bird Conservation Program. Cornell
Laboratory of Ornithology, Ithaca, New York.
Butcher, G.S., B. Peterjohn, and C.J. Ralph. 1993. Overview of National bird
population monitoring programs and databases. pp. 192-203 in D.M. Finch and P. W.
Stangel (Eds.), Status and Management of Neotropical Migratory Birds. USDA Forest Service,
General Technical Report RM-229.
Butcher, G.S. 1995. Applied bird population studies in the United States and
Latin America. pp. 447-450 in J.A. Bissonette and P.R. Krausman, eds. Integrating
people and wildlife for a sustainable future. Proceedings of the first International wildlife
Congress, San Jose, Costa Rica. The wildlife Society, Bethesda, Maryland.
Dunn, E. 1995.
Recommended
methods for regional checklist programs.
Migration Monitoring Councel, Partners in Flight. 11 p.
Hussell, D. and C.J. Ralph. 1996.
Recommended
methods for monitoring bird populations by counting and capture of migrants.
Migration Monitoring Council, Partners in Flight. 13 p.
Ralph, C.J. and B. Milá. 1995. Towards an integrated and standardized
monitoring program for landbirds in Latin America. pp. 676-678 in J.A. Bissonette and
P.R. Krausman, eds. Integrating people and wildlife for a sustainable future. Proceedings of the
first International wildlife Congress, San Jose, Costa Rica. The wildlife Society, Bethesda,
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by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: Pacific Southwest Research
Station, Forest Service, U.S. Department of Agriculture. 187 pages.
Ralph, C.J., G. Geupel, P. Pyle, T.E. Martin, D.F. DeSante, and B. Milá.
in press. Manual de metodos de campo para el monitoreo de aves terrestres. Gen. Tech. Rep.
PSW-GTR-159. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S.
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Rosenberg, K.V. and D. A. Wiedenfeld (Compilers). 1993. Directory of
Neotropical ornithology. Second Edition. American Ornithologists' Union. (Museum of Natural
Science, Louisiana State University, Baton Rouge, LA 70803).
Twedt, D.J, P.B. Hamel, M.S. Woodrey and R.J. Cooper. draft ms. Evaluation
strategy for neotropical migratory bird conservation goals of the Mississippi Alluvial Valley
Migratory Bird Initiative. MS supplied by author. 24 pp.
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