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A Comprehensive Review of Observational and Site Evaluation Data of Migrant Whooping Cranes in the United States, 1943-99



Although the data are observational only, and cannot provide unbiased information on habitat use by whooping cranes, there is some merit in continuing to collect data on incidental sightings of whooping cranes during migration, and to collect some specific habitat information at those locations. One example of the data's value is the recent use of whooping crane locations and dates of occurrence by flyway biologists to examine possible conflicts between the snow goose conservation action with migrating whooping cranes. Continuation of data collection, with periodic reviews, will likely provide insights into areas used by migrant whooping cranes and possible shifts in stopover areas. However, we strongly recommend that future data collection efforts be carefully considered and designed to reduce the biases inherent in observational data. The main database probably always will have inherent biases because of unequal observation effort among regions or years, and this needs to be recognized at all times. However, states or regions within states could be targeted for more objective data collection. Areas of particular interest could be targeted to systematically survey for whooping cranes and to document their use-days and habitat use. With appropriate design, such surveys could address questions about effects of habitat condition (e.g., occurrence or use-days of whooping cranes during drought periods) or management (e.g,. moist-soil management or other water management efforts). Caution must be exercised, however, in interpreting data; information collected in 1 area cannot be assumed to apply to other, unsurveyed areas.

The current system of data collection and entry needs to be thoroughly reviewed and revised, mainly to improve efficiency of translating field observations into an electronic records and to simplify field observations. The current system evolved over several decades which included the advent of personal computers and changing ideas about database management and what should be recorded. We believe simplifying the information recorded in the field would enhance the participation of observers by making the task more attractive and requiring less time. But coordinators of such a database also must develop incentives to encourage more participation to contribute both confirmed sightings and habitat data, especially in states or areas within states where there appear to be gaps. For example, local wildlife area managers, active birders, or interested ranchers in more remote regions (e.g., Nebraska Sandhills region, southwestern North Dakota) could be encouraged to participate through educational efforts and improved communication.

Although data sheets for observers in the field can be simplified, especially in terms of the habitat information collected, it also is important to tighten up the protocol for data collection and the definitions so that the data collected are more consistent and more accurate across observers and states. We recommend that the USFWS engage an experienced biologist to simultaneously develop the new database and to more carefully define categories, protocol, and possibly survey designs. The new database should be fully compatible with the existing database but also designed for more efficient data entry and management. If specific states or organizations decide to collect information beyond that in the USFWS efforts, it will be important to coordinate with those groups for consistency in protocol and data sharing.

From our experience working with the current data, we provide below some recommendations on both general data collection and management aspects and on the various variables recorded. The recommended changes made below should be carefully considered and discussed with biologists/observers from different states before implementation. One should consider what whooping cranes encounter in their migration range and what is of real significance (e.g., is it important to differentiate between use of green rye vs. green spring wheat). Also, these measures of "use" must be broad enough to encompass the entire flyway with some consistency and with some biological value. More specific examination of habitat use (e.g., use of CRP vs. alfalfa) should be the focus of targeted studies that will have more intensive measures of use and availability.

Specific Recommendations

  1. Continue to have 1 person or office responsible for data collation, entry, and periodic review or summation. This person would maintain paper records and the central electronic database, as well as inform and coordinate with biologists or other observers in each state. Ideally, this person or office should be with USFWS, which is charged with the management and protection of this endangered species.

  2. Combine variables currently used in the Observation and Site Evaluation databases into a single data reporting form and data set. This would allow for more direct linking of variables and minimize errors between data sets. One could still have multiple sub-observations and site locations within 1 main observation, but have a specific category indicating which records have site evaluation variables recorded. Such a data reporting form would have 2 sections, 1 for basic observation information (as currently recorded in Observations) and a separate section for site evaluation data. See recommendations below for specific suggestions on changes to both sections.

  3. Use numeric observation and location codes, as we created here, to identify unique records and to allow for easy extraction of information. Continue current system of sequential numbering of main and sub-observations reported.

  4. Develop data collection protocol for cooperators and the data manager, including clear, concise definitions of each variable and instructions on how to complete the data form in the field. Biologists or key observers from all states should be consulted during development of the protocol to ensure clarity, consistency, and simplicity, and to circumvent possible differences in interpretation of requested information.

  5. Maintain a paper copy of each submitted, confirmed observation, even if the report is submitted by phone or e-mail. The main value of paper copies is for map locations (see below), data proofing, and potential source of miscellaneous comments that might not fit into the data structure.

  6. For all confirmed observations, require field observers to plot observations clearly on a county or township-scale map which shows township, range, and section information; locations should be clearly marked and, if multiple observations occur, clearly labeled. This will allow the data manager to readily proof and enter the legal description data with minimal error and effort. Other maps sources, such as NWI maps, soil maps, NRCS crop photographs, or other pertinent types of maps, may be desirable but should be considered as supplemental. These maps should be maintained in the file with any paper copies of all confirmed observations.

  7. Maintain the database in Access. We assume this database software will remain a standard of the Department of Interior and many states for some time and that this format will be readily convertible to other software systems. Data entry in Access can be structured to provide pull-down menus, numeric-limited entry, or other constraints or options to ensure high quality of data entered.

  8. Summarize data annually and provide a state and national summary to participating states and key observers to reward and encourage their continued participation. As part of this, convert legal descriptions to Albers equal area projection in order to plot locations. Such reports also may provide an opportunity for cooperators to note possible errors or areas of concern.

  9. Develop well-defined seasons based on biological factors. The current determination of fall versus winter seasons seems somewhat arbitrary and more driven by location than date. Currently, observations of cranes in or near Aransas NWR and those of marked birds that previously had been sighted that fall/winter in Aransas NWR are classified as winter. Thus, a crane observed in Aransas NWR in mid-November is classified as winter whereas another crane observed in central Texas in mid- to late December would be classified as fall. Further, unmarked cranes may not stay near Aransas NWR, but any December observations elsewhere would be classified as fall since no additional information was available. Although this approach may seem appropriate for defining a migrant crane versus 1 that has arrived at its winter location, it allows no flexibility if cranes do not winter at Aransas NWR, or if they subsequently move away from the Aransas area. Similarly, we found some confusion in the original files in classifying spring versus summer records if cranes still were present in the United States after mid-May.

Observation Data Set Variables:

Site Evaluation Data Set Variables:

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