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Inventory & Monitoring

Landbirds | Raptors | Shorebirds | Waterbirds | Waterfowl

    Corps Level 1 and Level 2 Inventories


      What Landbirds Potentially Occur on My Project?
      Access to the Partners in Flight species assessment database at Rocky Mountain Bird Observatory – click the region within which your project occurs to obtain a species list.

      Points counts are the most commonly used method employed to inventory and monitor breeding bird populations

      Points counts consist of tallying all birds detected visually or aurally by a single observer from a fixed station during a specific period

      • A series of points are established in an area
      • Observer visits points during optimal times to detect birds of interest
      • At each point, observer records all birds detected (sight and sound) within specified time and distance.
      • Most detections are by ear, usually of singing males
      • It is critical that personnel conducting surveys know songs and calls of species in the area

      How do I conduct a point-count sampling effort?

      Download publications below to address specific methodological issues such as:

      • Why Point Counts?
      • Expertise Required to Conduct Point Counts
      • Timing of Visits
      • Length of Counts
      • Sampling Radius
      • What to Record
      • Weather Factors
      • Data entry and analysis

      Point Count Methodology Publications
      Guilfoyle, M.P. and Fischer, R.A. (2006). "Guidelines for Establishing Monitoring Programs to Assess the Success of Riparian Restoration Efforts in Arid and Semi-Arid Landscapes," EMRRP-SR-50, U.S. Army Engineer Research and Development Center, Vicksburg, MS.

      Hamel, P. 1996. Land Manager’s Guide to Point Counts in the Southeast. USFS GTR-SO.

      Huff et al. 2000. A Habitat-Based Point-Count Protocol for Terrestrial Birds, Emphasizing Washington and Oregon. PNW-GTR-501.

      Handbook for Monitoring Birds. 1993. USDA Forest Service Gen. Tech. Rep. PSW-GTR-144. 1993.


      The purpose of inventorying raptors might appear obvious: it is hard to manage for this group of birds or any group of birds without basic presence or absence information, just as a starting point. Trend and status of various raptors cannot be determined unless there is baseline data, and subsequent data collected using a standardized technique, a process that will help ensure consistent comparable results. This page provides current information regarding inventory and monitoring techniques for raptors.

      North American Raptor Monitoring Strategy
      The USGS Forest and Rangeland Ecosystem Science Center, Snake River Field Station, and Boise State University, Raptor Research Center, along with many collaborators, are developing a strategy for monitoring diurnal raptors throughout North America. Development of a continental monitoring program for raptors was initiated in July 1996 during the North American Raptor Monitoring Workshop held in Boise, Idaho. The purpose of the workshop was to address the needs of various bureaus in the Department of the Interior and other government agencies for practical ways to determine the status and trends of raptor species. Representatives from Canada, Mexico, and the United States participated.

      During the workshop, participants endorsed the need for a continental strategy and began organizing a program for its development. The key to development of the strategy, it was felt, would be species-by-species evaluations of existing monitoring programs and monitoring needs. In the months following the workshop, we completed a workshop report, formed an e-mail discussion group, proposed criteria for evaluating monitoring data, and established a format for presenting species accounts.

      Currently we are developing species accounts for most diurnal North American raptors. We now have about 40 scientists and raptor specialists who are willing in varying ways and extents to contribute to development of the accounts. Development will involve: 1) evaluation of the literature and existing databases for methods and data useful for monitoring each species; 2) identification of weaknesses in existing monitoring programs (with respect to methodology, geographic coverage, and seasonal coverage); 3) description of existing procedures for overcoming weaknesses; and 4) recommendation of new procedures and approaches where needed.

      The result of this effort will be a North American Raptor Monitoring Strategy consisting of individual species accounts and a synthesis identifying the best techniques and most efficient approaches for long-term monitoring. The species accounts will include details to support conclusions about how well each species currently is monitored, by what methods, in what areas, and at what seasons of the year. The integration of that information will reveal situations in which groups of species are well monitored by a given method (e.g., the Breeding Bird Survey), in a certain area (e.g., the Upper Mississippi Valley), and/or within a particular season (breeding, migration, winter). The strategy will include recommendations for general and specific improvements in study design, sampling, and data analysis. Ultimately, the North American Raptor Monitoring Strategy will provide a sound scientific and statistical basis for monitoring raptor populations based on comprehensive, up-to-date information. Wildlife and land managers will be able to use the strategy as a basis for deciding what long-term monitoring to undertake, and for conclusions about the current status and trends of many species. The strategy will alert managers and policy makers to the paucity of available information in many cases, and the need for new survey and monitoring methods. The strategy is scheduled to be completed in 2004.

      How Do You Conduct Basic Inventories If Trained Staff are not Available?

      • Contact local or national bird watching organizations, such as the American Birding Association (ABA). Frequently, they have motivated, highly skilled observers willing to assist Corps staff in these activities. In certain circumstances they will arrange the survey, conduct the survey and supply a written report (link to example of a report provided by birding organization - Bartramiam Audubon, Mercer Co. PA, Pittsburgh District.
      • ABA link
      • Participate in existing survey efforts, such as Christmas Bird Counts, state atlas programs and International Migratory Bird Day, to name just a few.
      • International migratory bird day


      Surveying shorebirds can be a challenging endeavor. Over 70 species have been recorded in North America and each species or distinct population has its own migration strategy for traversing from the wintering grounds to breeding territories. Accessibility for the human observer varies among the species' wintering and breeding grounds as well.

      Precision and bias are two critical aspects of accuracy in any given survey. Precision refers to the effect of errors caused by chance factors such as when surveys are made, in what areas, by whom, or by weather or habitat changes. Increasing the sample size improves precision. Standard errors and confidence intervals are common measures of precision.

      Bias refers to the effect of errors caused by consistent tendencies to over- or under-estimate the quantity of interest. Three sources of bias are errors caused by low or variable detection rates, exclusion of important shorebird areas from the survey program and certain long-term shifts in shorebird distribution patterns. Using larger sample sizes, no clear relationship between bias and sample size can be expected.

      Estimating population trends, population size, and trends in shorebird use of stopover areas are types of typical shorebird surveys. Both the International Shorebird Survey (ISS) and the Program for Regional and International Shorebird Monitoring (PRISM) are survey and monitoring programs intended for carrying out shorebird conservation plans recently adopted bu the United States and Canada. Surveys can be conducted on the breeding grounds or wintering grounds as well as during migration. During breeding season, individual birds tend to show strong fidelity to previous years' breeding sites. The populations tend to be stable for longer periods of time as nesting is underway and attention to young is of high importance. On the other hand, surveying shorebirds on the wintering grounds can be advantageous as high concentrations generally occur at specific sights. Adults and juveniles will be together and the wintering behavior is much more sedentary. Surveying shorebirds during their migration to and from wintering to breeding grounds can present some challenges as well. Most of the major stopover points are well known. Volunteer observers can be utilized as many of these areas are known birding sites. Both aerial counts and ground-based counts are utilized. Aerial counts can be difficult for species identification, poor visibility and escape response to aircraft. Ground-based surveys cannot cover as many groups of birds as the aerial surveys can; however, the accuracy of the survey is greater and identification to species is more likely to occur. Turnover rates or length-of-stay is another important factor for shorebird surveyors to consider.

      For additional information and sources of the above information:

    Shorebird Monitoring

      Widespread destruction and loss of habitats preferred by shorebirds are causing rapid changes to bird populations, as well as other wildlife species, throughout the world. Information on how bird populations are changing is becoming more important to wildlife managers. Early detection of these changes is very important for management decisions. An example of information on population size, population vulnerability and population change has been the main point for international conservation strategies such as the Ramsar Convention, the Western Hemisphere Convention and the Western Hemisphere Shorebird Reserve Network.

      Monitoring and surveys for determining population size can be simple but very costly.

      In 1999, a group of shorebird authorities reviewed the current status of shorebirds in the United States and evaluated the capacity of existing programs for monitoring shorebird populations. They came up with goals and objectives necessary for a successful shorebird monitoring program.

      See the goals and objectives and other relevant information on the Manomet Center for Conservation Sciences website below:

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