Midwinter Bald Eagle Counts, 1986-2005 (update 2008)

Frequently-anticipated questions:

What does this data set describe?

Title: Midwinter Bald Eagle Counts, 1986-2005 (update 2008)
Abstract:
as part of a survey initiated in 1979 by the National Wildlife Federation. This database includes data from 1986-2005 midwinter counts and includes some statewide, regional and national trends. Survey routes are included in the database only if they were surveyed consistently in at least 4 years and where at least 4 eagles were counted in a single year.
  1. How should this data set be cited?

    U.S. Geological Survey, National Biological Information Infrastr, 2008, Midwinter Bald Eagle Counts, 1986-2005 (update 2008):.

    Online Links:

    Other_Citation_Details:
    This work is supported by the National Biological Information Infrastructure (NBII)
    This is part of the following larger work.

    Karen Steenhof, Laura Bond, Kirk K. Bates, and Lynda , 2002, Trends in midwinter counts of bald eagles in the contiguous United States, 1986-2000: Bird Populations 6:21-32.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -125
    East_Bounding_Coordinate: -66
    North_Bounding_Coordinate: 49
    South_Bounding_Coordinate: 24

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 1986
    Ending_Date: 2005
    Currentness_Reference: date of survey

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Database

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

    2. What coordinate system is used to represent geographic features?

  7. How does the data set describe geographic features?

    EagAllRouteInfo2 (SherryAllRoutes)
    Microsoft Access database table containing summary information about all surveyed routes included in the dataset (Source: Microsoft)

    Annual Percent Change (ANNCHNG)
    Estimated rate of annual change on route (Source: NACSE)

    Range of values
    Minimum:undetermined minimum
    Maximum:undetermined maximum
    Units:percent

    Count Trend (Trend)
    Increasing or decreasing trend in bald eagle counts (Source: NACSE)

    Range of values
    Minimum:undetermined minimum
    Maximum:undetermined maximum
    Units:percent

    Ecoregion (BCR)
    Bird Conservation Region code (Source: Dataset Developer)

    Formal codeset
    Codeset Name:Bird Conservation Region Codes <http://www.nabci-us.org/aboutnabci/bcrdescrip.pdf>
    Codeset Source:North American Bird Conservation Initiative

    Ecoregion Group (BCRGroup)
    Combined Bird Conservation Regions (Source: Dataset Developer)

    ValueDefinition
    East CoastNEW_ENGLAND/MID-ATLANTIC_COAST; SOUTHEASTERN_COASTAL_PLAIN
    Eastern WoodlandAPPALACHIAN_MOUNTAINS; ATLANTIC_NORTHERN_FOREST; CENTRAL_HARDWOODS; PIEDMONT
    Great BasinGREAT_BASIN; SIERRA_NEVADA
    Great LakesBOREAL_HARDWOOD_TRANSITION; LOWER_GREAT_LAKES/_ST._LAWRENCE_PLAIN; PRAIRIE_HARDWOOD_TRANSITION
    GulfGULF_COASTAL_PRAIRIE; MISSISSIPPI_ALLUVIAL_VALLEY; OAKS_AND_PRAIRIES; WEST_GULF_COASTAL_PLAIN/OUACHITAS
    Pac CoastCOASTAL_CALIFORNIA; NORTHERN_PACIFIC_RAINFOREST
    PrairieBADLANDS_AND_PRAIRIES; CENTRAL_MIXED_GRASS_PRAIRIE; EASTERN_TALLGRASS_PRAIRIE; EDWARDS_PLATEAU; PRAIRIE_POTHOLES; SHORTGRASS_PRAIRIE
    RockiesNORTHERN_ROCKIES; SOUTHERN_ROCKIES/COLORADO_PLATEAU
    SW DesertCHIHUAHUAN DESERT; SIERRA MADRE OCCIDENTAL; SONORAN_AND_MOJAVE_DESERTS

    Formal codeset
    Codeset Name:BCRIndex

    Maximum Adult Bald Eagles (MaxAd)
    Maximum number of adult bald eagles seen on route (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:unknown

    Maximum Bald Eagles (MaxBE)
    Maximum number of bald eagles seen on route (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:unknown

    Maximum Immature Bald Eagles (MaxImm)
    Maximum number of immature bald eagles seen on route (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:unknown

    Mean Number of Adult Bald Eagles (MeanAd)
    Mean number of adult bald eagles seen on route (Source: NACSE)

    Range of values
    Minimum:0
    Maximum:unknown

    Mean Number of Bald Eagles (MeanBE)
    Mean number of bald eagles seen on route (Source: NACSE)

    Range of values
    Minimum:0
    Maximum:unknown

    Mean Number of Immature Bald Eagles (MeanImm)
    Mean number of immature bald eagles seen on route (Source: NACSE)

    Range of values
    Minimum:0
    Maximum:unknown

    Potential Concentration Area (PCA)
    We defined routes to be in eagle concentration areas if >15, 50, 80, or 100 eagles were counted on routes in the respective length categories (0-17 km, 18-56 km, 57-120 km, and >120 km). (Source: Dataset Developer)

    ValueDefinition
    HighArea meets criteria in definition
    LowArea does not meet criteria in definition

    Region
    Routes were divided into 4 regions, based on position relating to 100th meridian and 40th parallel (Source: Dataset Developer)

    ValueDefinition
    NorthWest 
    NorthEast 
    SouthWest 
    SouthEast 

    Site Number (SiteNumb)
    Route site number (Source: Dataset Developer)

    A unique alphanumeric string identifying the route within each state; note that alphanumeric codes are unique within states; some states may use the same sitenumb.

    State
    Two letter postal code for each state (Source: FIPS PUB 5-2)

    Formal codeset
    Codeset Source:Federal Information Processing Standard, Pub 5-2 <http://www.itl.nist.gov/fipspubs/fip5-2.htm>

    StateTwo
    Two letter postal code for a second state also surveyed along the survey route (often along a shared water boundary) (Source: FIPS PUB 5-2)

    Formal codeset
    Codeset Source:Federal Information Processing Standard, Pub 5-2 <http://www.itl.nist.gov/fipspubs/fip5-2.htm>

    Years of Observation (Numyrobs)
    Number of years route was surveyed, from 1986-2005 (Source: Dataset Developer)

    Range of values
    Minimum:1
    Maximum:15

    EagMIDWINpacked2 (MidwinSherry)
    Microsoft Access data table of raw data from all surveys used (Source: Microsoft)

    Cloud Cover (Cloud)
    Cloud cover during the survey (Source: Dataset Developer)

    ValueDefinition
    1Clear
    2Foggy then clearing
    3Foggy
    4Partly cloudy
    5Cloudy then clearing
    6Cloudy
    7Not listed

    COMPLETE
    Each year a value was assigned indicating completeness of the survey (Source: Dataset Developer)

    ValueDefinition
    1Yes
    2No
    3Assumed complete
    4Not surveyed

    Fog
    Indicates whether fog was present on the day of the survey (Source: Dataset Developer)

    ValueDefinition
    1No; fog not present
    2Yes; foggy conditions

    ICE
    Description of amount of ice in comparison to normal amount on the survey date (Source: Dataset Developer)

    ValueDefinition
    1Much less than normal
    2Less than normal
    3Normal
    4More than normal
    5Much more than normal
    6Not listed

    Latitude
    Latitude of survey area (Source: Dataset Developer)

    Range of values
    Minimum:20
    Maximum:50
    Units:degrees

    Longitude
    Longitude of survey area (Source: Dataset Developer)

    Range of values
    Minimum:-130
    Maximum:-60
    Units:degrees

    MethodsofTravel3 (Method3)
    A hierarchical approach was used to classify survey methods. If multiple survey methods were used, we classified it as AIR if any part of it was done aerially. If no aerial methods were used, we classified it as WATER if a boat was used for all or part of the survey. We classified survey method as GROUND if planes, boats, and helicopters were NOT used. Ground surveys included foot, vehicle, skis, and snowmobile. (Source: Dataset Developer)

    ValueDefinition
    airif any part of it was done aerially
    waterif a boat was used for all or part of the survey
    groundif planes, boats, and helicopters were NOT used. Ground surveys included foot, vehicle, skis, and snowmobile

    MethodsofTravel4 (Method4)
    Travel methods used to conduct surveys (Source: Dataset Developer)

    ValueDefinition
    AIRCRAFT 
    AIRCRAFT & BOAT 
    AIRCRAFT & FOOT 
    ATV 
    BIKE 
    BOAT 
    BOAT & ATV 
    BOAT & FOOT 
    FIXED POINT 
    FIXED WING 
    FOOT 
    FOOT & RAILROAD 
    FOOT & SNOWMOBILE 
    HELICOPTER 
    MULTIPLE (>2) 
    RAILROAD 
    SKIS 
    SKIS/SNOWSHOES 
    SNOWMOBILE 
    SNOWMOBILE & OTHER 
    UNKNOWN 
    VEHICLE 
    VEHICLE & AIRCRAFT 
    VEHICLE & AIRCRAFT & BOAT 
    VEHICLE & AIRCRAFT & BOAT & FOOT 
    VEHICLE & AIRCRAFT & FOOT 
    VEHICLE & ATV 
    VEHICLE & BOAT 
    VEHICLE & BOAT & FOOT 
    VEHICLE & BOAT & SNOWMOBILE 
    VEHICLE & FIXED POINT 
    VEHICLE & FOOT 
    VEHICLE & FOOT & ATV 
    VEHICLE & FOOT & RAILROAD 
    VEHICLE & FOOT & SNOWMOBILE 
    VEHICLE & OTHER 
    VEHICLE & SKIS 
    VEHICLE & SNOWMOBILE 
    VEHICLE, FIXED WING & SNOWMOBILE 

    MILES
    Amount of shoreline surveyed: 1-way direction on a river or miles of shoreline habitat on a lake/reservoir surveyed from 1 or more viewpoints (Source: Dataset Developer)

    Range of values
    Minimum:1
    Maximum:undetermined maximum
    Units:miles

    Number of Adult Bald Eagles (AdultBE)
    Number of adult bald eagles counted (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:undetermined maximum

    Number of Days (Days)
    Number of days on which the survey took place (Source: Dataset Developer)

    Range of values
    Minimum:1
    Maximum:undetermined maximum

    Number of Immature (ImmatureBE)
    Number of immature bald eagles (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:undetermined maximum

    Number Unknown (UnknownBE)
    Number of unknown bald eagles, not identified as adult or immature (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:undetermined maximum

    OBSERVNO
    The number of observers on a given route in a given year (Source: Dataset Developer)

    Range of values
    Minimum:1
    Maximum:undetermined maximum

    Percent of Ice (PercentIce)
    Percent of ice along survey route (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:100
    Units:percent

    Precipitation
    Whether precipitation was present at time of survey (Source: Dataset Developer)

    ValueDefinition
    1No
    2Yes

    Precipitation Type (Precip)
    Type of precipitation at time of survey (Source: Dataset Developer)

    ValueDefinition
    1None
    2Snowy
    3Rainy
    4Not listed

    Principal Drainage (Drainbody)
    The major river drainage in which a route occurs (Source: Dataset Developer)

    unbounded list of river basins

    ROOST
    Was the survey conducted at a known night roosting area (Source: Dataset Developer)

    ValueDefinition
    ROKnown night roosting area
    NRNon-roosting area
    BOBoth roosting and non-roosting areas

    ROUTE
    Route type (Source: Dataset Developer)

    ValueDefinition
    COContinuous route
    FPFixed point
    BOBoth continuous and fixed point routes

    Route Name (Placename)
    Name given to a route (Source: Dataset Developer)

    unbounded list of names

    Site Number (Sitenumb)
    Site number (Source: Dataset Developer)

    A unique alphanumeric string identifying the route within each state; note that alphanumeric codes are unique within states; some states may use the same sitenumb

    Size
    Length class of route (Source: Dataset Developer)

    ValueDefinition
    10-17 km (0-10 miles)
    218-56 km (11-35 miles)
    357-120 km (36-75 miles)
    4more than 120 km (>75 miles)

    SOMEICE
    Whether some amount of ice was present (yes or no) (Source: Dataset Developer)

    ValueDefinition
    yes (Y)Some ice present
    no (N)No ice present

    State (StateName)
    Name of State (Source: Dataset Developer)

    list of state names

    StateNameTwo
    Name of a second state also surveyed along the survey route (often along a shared water boundary) (Source: Database Developer)

    list of state names

    SurveyDate
    The date a survey was conducted (Source: Dataset Developer)

    date field (Microsoft format)

    Temperature (Temp)
    Temperature in Fahrenheit degrees at time of survey (Source: Dataset Developer)

    Range of values
    Minimum:undetermined minimum
    Maximum:undetermined maximum
    Units:degrees, Fahrenheit

    TIMESTART
    Time of day the survey began (Source: Dataset Developer)

    variable time formats

    Total Bald Eagles (TotalBE)
    Total number of bald eagles (Source: Dataset Developer)

    Range of values
    Minimum:0
    Maximum:undetermined maximum

    TOTALTIME
    Number of minutes from beginning to end of survey (Source: Dataset Developer)

    Range of values
    Minimum:1
    Maximum:undetermined maximum
    Units:minute
    Resolution:1

    WEATHER
    Description of the weather at time of survey (Source: Dataset developer)

    ValueDefinition
    1Very mild
    2Mild
    3Normal
    4Harsh
    5Very harsh
    6Not listed

    Wind
    Description of wind at time of survey (Source: Dataset Developer)

    ValueDefinition
    LWLight; 1-7 mph
    MWModerate; 8-18 mph
    NLNot listed
    NWNo wind; calm
    SWStrong; >18 mph

    Year
    The year in which the survey took place, ranging from 1986-2005 (Source: Dataset Developer)

    Range of values
    Minimum:1986
    Maximum:2005

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    Early development of the database was done by the National Wildlife Federation. The Bureau of Land Management supported development from 1991 - 1993 and the National Biological Survey (now USGS-BRD) continued support from 1993-1996.

  3. To whom should users address questions about the data?

    USGS Forest & Rangeland Ecosystem Science Center (FRESC)
    U.S. Geological Survey
    Forest and Rangeland Ecosystem Science Center
    777 NW 9th St.
    Corvallis, Oregon 97330
    USA

    (541) 750-1030 (voice)

Why was the data set created?

Initial objectives were to determine eagle distribution during winter, identify previously unrecognized areas of important winter habitat, and estimate the wintering Bald Eagle population in the lower 48 states. The current purpose of the midwinter bald eagle count is to estimate national and regional Bald Eagle count trends overall and by age class.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: Unknown (process 1 of 1)
    Original data collection; no processing

  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Because survey routes were not randomly selected, we do not know if the standard routes used in this analysis are representative of the contiguous 48 states. Our findings are likely biased towards states and portions of states where agencies and individuals were committed to long-term, consistent data collection. Within those areas, our sampling has emphasized river stretches and water bodies where Bald Eagles are known to occur. The survey, therefore, represents a type of ""convenience sampling"" and is subject to inferential constraints outlined by Anderson (2001). The midwinter counts cannot be used to estimate actual population size, and inferences about trends must be restricted to the areas sampled by survey routes.

  5. How consistent are the relationships among the observations, including topology?

    We received more than 15,000 reports of surveys conducted from 1986 to 2005. We reviewed all survey forms to ensure that the number of eagles reported in each age class tracked with the total number reported. We excluded surveys from the analysis if: (1) the count was conducted before 1 Jan or after 25 Jan; (2) the route covered was inconsistent from year to year; (3) the route was not described clearly enough to determine if it was similar to other years; (4) the survey method was not listed; or (5) we were unable to obtain information on size of the survey route. We tried to verify that route coverage was consistent from year to year by comparing reported mileages among years. In many cases, we contacted observers and state coordinators to verify starting and ending points as well as total area surveyed. We corrected or eliminated records when we became aware of cases where observers covered areas less than or greater than the defined standard route. We only used data from routes that were surveyed consistently in at least 4 years where at least 4 eagles were counted in a single year. Survey routes with <4 eagle observations/year are probably in marginal or unsuitable wintering habitat; including data from routes where few or no eagles were ever seen would have biased our trend estimates towards zero. We evaluated count data to determine if fog, precipitation, or changing transportation methods might have affected the ability of observers to detect eagles and thereby influence trend estimates. Based on our evaluation, we excluded surveys that used a different transportation method on a particular route in a minority of years, but we included surveys conducted during fog or precipitation. After all exclusions, our final data set includes 178,896 observations of eagles during 8,674 surveys of 746 routes in 43 states.

    Our analyses indicated that we could not use a survey route in the trend analysis if the method of survey (air, ground, water) changed. So if we have 10 years of aerial survey on a given route and 1 year of ground survey, we have to throw out the ground survey. However, if we have at least 4 years of aerial surveys and at least 4 years of ground surveys (different years than the aerial surveys), we have considered them as separate routes and use both of them in the analysis.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints: None

  1. Who distributes the data set? (Distributor 1 of 1)

    USGS Forest & Rangeland Ecosystem Science Center (FRESC)
    U.S. Geological Survey
    Forest and Rangeland Ecosystem Science Center
    777 NW 9th St.
    Corvallis, Oregon 97330
    USA

    (541) 750-1030 (voice)

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from a U.S. Geological Survey server, and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    Available online at: <http://ocid.nacse.org/nbii/eagles/>

Who wrote the metadata?

Dates:
Last modified: 04-Jan-2008
Last Reviewed: 04-Jan-2008
Metadata author:
USGS Forest & Rangeland Ecosystem Science Center (FRESC)
U.S. Geological Survey
Forest and Rangeland Ecosystem Science Center
777 NW 9th St.
Corvallis, Oregon 97330
USA

(541) 750-1030 (voice)

Metadata standard:
FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata (FGDC-STD-001.1-1999)

Generated by mp version 2.8.22 on Wed Jan 09 16:32:37 2008