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General Questions
1. What is the Bird Avoidance Model?
The Bird Avoidance Model is used as a key tool for analysis, predictability, and correlation of bird habitat, migration, and breeding characteristics, combined with key environmental, and man-made geographic data.
2. Why was the model created?
The model was created to provide Air Force pilots and flight scheduler/planners with a tool for making informed decisions when selecting flight routes. The model was created in an effort to protect human lives, wildlife, and equipment during air operations throughout the conterminous United States and Alaska.
3. Who uses the model?
The model is used by the Department of Defense and is now available to the general public through this Internet application.
4. How was the model created?
The value for each cell (or pixel) of the model is equivalent to the sum of the mean bird mass (in ounces), for all bird species present during a particular daily time period, for one of 26 two-week periods in a year. The bird species data set was derived from discrete geographic information for observations of 60 key BASH bird species, over a 30-year period. The species data was acquired from several key datasets, including the Audubon Societies' Christmas Bird Count (CBC), the US Biologic Survey's Breeding Bird Survey (BBS), bird refuge arrival and departure data for the conterminous US, and many additional data that are specific to a particular bird species.
The bird abundance observations were interpolated using an inverse distance weighted method to reduce interpolation bias. The interpolated abundance values were then converted to bird mass using the mean weight of adult birds, measured in ounces. The bird species data were then combined for different species groups based on common behavior. The species groups were then modeled for dawn, day, dusk, and night daily periods, for each of 26 annual two-week periods.
5. What do the risk levels really mean?
The risk levels describe three predicted risk classes - Low, Moderate, and Severe, which are based upon the bird mass in ounces per square kilometer. In other words, the risk levels represent the amount of birds (bird mass) in a kilometer squared spatial area.
The "Moderate Zone" indicates a risk ratio that is 57-708 times the risk of the "Low Zone", while the "Severe Zone" indicates a risk ratio that is 2,503-38,647 times the risk of the "Low Zone"! These risk values are derived using a logarythmic scale for the risk surfaces.
6. Is it safe to fly if I am within a "Severe Zone"?
The model uses the best available data for historical modeling of bird migratory patterns to provide the user with an effective decision making tool. Because birds are dynamic creatures whose migratory behavior is initiated by weather events in any given year, the model can not be said to predict the exact movement of bird species through space and time beyond the biweekly timeframe. Spatial zones that indicate a severe risk according to the model should be not be ignored and should be avoided. It is not suggested that pilots fly within the "Severe Zone" unless it is mission essential.
To receive real-time data associated with bird migratory movement, the Avian Hazard Advisory System (AHAS) should be consulted. The AHAS provides users with real-time (i.e., 24 hour window) risk prediction of bird movement and is currently available for the conterminous United States and Alaska.
7. Where can I find more information about bird strikes?
- Avian Hazard Advisory System
AHAS provides users with real-time risk prediction of bird movement.
- Bird Strike Committee USA
The committee provides bird hazard and bird hazard prevention information.
- Bird/Wildlife Aircraft Strike Hazard Team
The team's goal is the preservation of war fighting capabilities through the reduction of wildlife hazards to aircraft operations.
Map Layer Questions
1. How accurate is the Breeding Bird Survey and Christmas Bird Count?
Breeding Bird Survey (BBS) and the Christmas Bird Count (CBC) sites are randomly selected and do not represent areas of increased risk associated with bird abundance and migration patterns.
2. North American Breeding Bird Survey (BBS)
The North American Breeding Bird Survey (BBS) data served as the source for interpolation of bird species abundance during the breeding season. The BBS database was obtained online from the USGS Patuxent Wildlife Research Center (comp.) website. The portions of the dataset used in the model spans a recording period of 38 years, beginning from May, 1966 and ending in June, 2003.
The Breeding Bird Survey (BBS) is conducted each year at survey sites across the US. 2167 sites were used in the development of the US BAM. Surveys occur at designated survey sites and are conducted along a 39.4 km route. The site coordinates are recorded and represent the starting point of each 39.4 km route. A digital database is then created in ASCII file format. This database contains route coordinates (starting point) with corresponding mean number of birds observed per route, per year. A 38 year mean was derived for each survey site.
3. Audubon Christmas Bird Count
The Audubon Christmas Bird Count (CBC) was used as the source for interpolation of bird species abundance during the wintering seasons. The CBC database was obtained online from the USGS Patuxent Wildlife Research Center (comp.) website. The dataset spans a recording period of 38 years, beginning from December, 1959 and ending in December, 1997.
The Audubon Christmas Bird Count Survey (CBC) is conducted each year at survey sites across the US. 2026 sites were used in the development of the model. Surveys are conducted at each of the CBC sites and occur within a 12.1 km radius of the site center point. A digital database is then created in ASCII file format. The ASCII database contains the coordinates of each site (center point) with mean number of birds observed per party hour, per count circle, per year. A 38 year mean was derived for each survey site.
4. Bird Refuge Databases
"Migrant" and Resident bird information were obtained from previously completed BAM research conducted by Spectrum Consultants Inc. in 1996. Recoverable raw Grass grids, obtained from LtCol Russ DeFusco, were translated from the Spectrum BAM using ERDAS Imagine software. The refuge database was recovered from corrupted files obtained in the Spectrum BAM databases. The refuge database provided information for 659 refuge locations.
The databases associated with refuges do not provide species distinctions. The migrant and resident information is recorded for general description bird groups: ducks, swans, geese, raptors, gulls, pelicans, cranes, blackbirds, waders, and shorebirds. The migrant bird databases include coordinate information for each refuge, arrival and departure information for biannual migration events for each of the general description bird groups, as well the dates and bird counts of biannual peak population occurrences (dates for arrival1, date of arrival2, date of peak1, date of peak2, date of departure1, date of departure 2, numbers of birds at peak). The arrival and departure dates represent the dates of arrival of a population for spring and fall migration periods. The resident bird database provides peak bird count numbers for each of the general description bird groups.
The species group arrival and departure dates associated with each refuge were analyzed in the BAM development to determine the migration pattern of the various species groups in space and time.
5. USAF Bird-Aircraft Strike Database
The Air Force Bird-Aircraft Strike database, maintained by the Bird Aircraft Strike Hazard Team of the Air Force Safety Center, Kirtland AFB, NM, was used to develop a map layer of known strike locations. The database was converted from Paradox to MS Access format. Records that did not contain geospatial locations associated with bird strikes were deleted from the MS Access file. Records associated with known strikes in Alaska, Canada, Hawaii, and Mexico were retained within the database for help in determining species migration routes. The geospatial coordinates within the database (degrees:minutes) were converted to decimal degrees, in order to correspond with the CBC and BBS datasets' geospatial coordinates units. Strike locations outside the conterminous United States, with the exception of Canada, Alaska, Mexico, and Hawaii were deleted from the dataset used to generate the Bird-Aircraft Strike Hazard map.
The database provides a historical perspective of hazards that have plagued the Air Force flying mission. This dataset represents bird strike data for a period of approximately 21.5 years (January, 1985-April, 2005). The database was also useful in determining the final list of species to be incorporated into the US BAM, since it was necessary to represent species that exhibited a high strike frequency. Bird strikes are represented in a point type dataset where each point represents the location of a historical strike. Attribute information for each point varies according to the information that was collected at the time of the strike.
The finalized bird-aircraft strike map was used to correlate bird migration locations during specified time periods with BBS and CBC observations. The map is included in the BAM as an additional data layer which may be overlaid on BAM predicted risk surfaces.
6. Landfill Locations
Point data for 250 landfills across the United States were developed from the EPA landfill database obtained from Mike Ebner, EPA Landfill Project Managers. At the time of BAM development this dataset was not complete enough to be include in the model development.
As a result of limited public domain data sources, private data distributors were researched for geospatial landfill datasets. The electronic version of the "Directory and Atlas of Solid Waste Disposal Facilities" was obtained from Chartwell Information Publishers (http://www.wasteinfo.com) on August 17, 2000. The dataset provides ArcView shapefiles containing 5,200 landfill, transfer stations, mixed waste facility, and waste incinerator facility point locations and facility profile files (.dbf).
The landfill shapefile, created from the "Directory and Atlas of Solid Waste Disposal Facilities" was not used for analysis purposes. This shapefile contains the geographic location of landfills, waste incinerators, and waste processing stations that deal with putrescent waste. The map is as an additional data layer in the BAM, which may be overlaid on the BAM risk category surfaces.
