Abstract:
A winter bird survey was conducted throughout Maryland, primarily by volunteers, during the 6 winters of 1988 to 1993 between the dates 10 Jan and 10 Feb. The state of Maryland is covered by 1231 blocks (9.5 sq. miles each), each comprising one-sixth of the standard U.S.G.S. 7.5 minute topographic quadrangle, and 548 of these blocks (44.5%) were surveyed for winter birds. Blocks were chosen in a ... systematic pattern with eventually almost every other block in the state having been surveyed as of Feb, 1993. Volunteers conducted each 4-hour survey by walking a 4-6 mile route chosen by the volunteer to sample habitats in proportion to their availability in the block. Surveys began around sunrise (7:30 a.m.) and all birds seen or heard during the 4 hours were recorded on data sheets. The data were then used to create maps representing the distribution and relative abundance of each species of wintering bird found in at least 10 blocks in the state.
Geographic Description: Maryland For the purpose of interpreting the maps, a brief discussion of the geography of the state and its physiographic regions (see Fig. 1a) follows. Maryland contains parts of 3 physiographic provinces (Frese 1994): Coastal Plain, Piedmont, and Appalachian. Elevations increase from sea level to 3360 feet, generally in an east-west progression. The Coastal Plain, part of the Atlantic Coastal Plain, is further divided on the map into the Upper Chesapeake, Eastern Shore, and Western Shore sections bordering the Chesapeake Bay. Elevations there are mostly less than 100 feet, with the topography low and flat except for the hilly country of the lower Western Shore. Major rivers are the Patuxent, Potomac, Chester, Choptank, Nanticoke, and Pocomoke, all of which drain into the Chesapeake Bay. Agriculture predominates, with much of the land cleared for soybeans, corn, wheat, hay, and on the lower Western Shore, tobacco. The Piedmont province is sandwiched between the fall line for streams and the eastern beginnings of the Catoctin mountains. The land is rolling and hilly, ranging in elevation from about 100 to 800 feet, and is drained mostly by the Potomac, Monocacy, Patapsco, Gunpowder, and Susquehanna rivers. Straddling the boundary between Coastal Plain and Piedmont are the heavily urbanized areas of Baltimore, Maryland, and Washington, D.C., both of which are surrounded by extensive suburban development that reaches far into both provinces. The Appalachian Province is composed of the Ridge and Valley and the Allegheny Mountain sections. The former section is characterized by ridges and steep mountains running northeast to southwest separated by mostly narrow valleys, with elevations in the 500 to 2000 feet range. The heavily forested Allegheny Mountain section is part of the Allegheny Plateau and contains the state's highest elevations, mostly in the range of 2000 to 3000 feet. Less than half of the land surface in the state is forested, with oak and hickory predominating, although Loblolly Pine prevails on the Eastern Shore. Mean annual snowfall accumulations range from about 100 inches in extreme western Maryland to 10 inches on the Eastern Shore. January is the coldest month, and mean temperatures for January and February range between the upper 20's and upper 30's degrees Fahrenheit.
Methodology: METHODS: Maryland has been divided into a grid of approximately 1200 blocks, each about 10 sq. mi. in size. This is the same grid system used in the Maryland Breeding Bird Atlas project. Each surveyed block will receive 4-hours of on-foot coverage by experienced birders. Due to the difficulties of attempting to survey all 1200 + blocks, only the blocks will be covered, namely a checkerboard pattern of "target" blocks. In the first year, alternate southern blocks in each 7 minute quadrangle will be surveyed, in the second year, middle blocks and in the third year, northern blocks. The cycle will then repeat in the 4th, 5th, and 6th years, to complete the targeted blocks. CHOOSING A ROUTE: It is important to cover a block in proportion to the habitats present in the block. For example, if the block contains 40% suburbs, 10% marsh, 10% fields, and 40% woods you should spend about 1 hours in the suburbs and in the woods and about hour in the marsh and in the fields. Most blocks can meet this criterion with one continuous 4-hour route. However, if the habitats present are too scattered, some driving is permitted. Do not exceed hour of driving time and do not count birds during that time or consider it part of the total 4 hours. It might also be necessary to retrace part of your route to sample an important habitat. Again, the time spent retracing should not be considered part of the 4 hours, nor should birds be counted. A walking speed of 1-1.5 miles per hour is suggested. Hence, 4 hours of coverage should be about 4-6 miles. This speed allows time to "work" mixed flocks of birds, but not to dawdle or sit. Complete roadside coverage is not recommended, but in some blocks it might be necessary. If a block dictates largely or entirely walking on roads, it will probably be easy to cover up to 6 miles. If you complete 4 hours of coverage before you complete your proposed route, stop counting and return to your car. If you reach your proposed end point before the 4 hours is up, extend coverage, but not along the already-covered route. If possible, examine the map and scout the area ahead of time, asking permission if necessary. Plan your route before the actual day of coverage. TIMING OF ROUTES: In order to keep the surveys comparable, a time period of 7:30-11:30 has been chosen. This avoids the brief period of intense bird activity at dawn, and everyone gets to sleep later. The survey can be extended up till noon to compensate for driving time, as described above. COUNTING: Each block will be visited once by one observer. A companion may act as recorder but should not help lure or spot birds. Pishing may be used to attract mixed flocks but no tapes or owl imitations are permitted. The object is not to maximize the number of birds recorded, but to survey winter birds in a uniform manner. Use the field sheet provided, counting all individual birds seen or heard in each of 8 half-hour segments. If you would rather not carry a clip board, a small note pad, with a page for each hour will be satisfactory. In blocks with water, time should not be spent scoping or waiting for birds. Open water or other special habitats like landfills should be surveyed following the 4 hours of foot coverage. The results from these special areas should be written in at the bottom of the form. Waterbirds flying over or in fields found during the walking portion of the survey should be treated like any other species. Upon completion of your survey be sure to record all weather information and mark the location of the route you took on the map. Also be sure to mark the location of the end point of each hour segment. GENERIC SPECIES: Winter birds are often difficult to identify to species. For completeness sake, please record all birds such as crows and gulls that you are not able to separate by species. REPORTING: After completing the count, transfer the data to the summary sheet provided, and fill in the weather data. Total the 8 columns and double-check the species total for each column to make sure it agrees with the species total for each half-hour on the field sheet. Please return your field sheets and maps. These maps are from a personal collection and their replacement is expensive. WEATHER CODES: Please record the percentage of ground that is covered with snow and the percentage of ice on the water bodies in your block. Please record wind speed using the following codes: 0 - smoke rises vertically, 1 - smoke drifts, 2 - wind felt on face, 3 - light flags extended, 4 - wind raises dust and loose paper, 5 - crested wavelets on inland waters. Please record sky conditions using the following Weather Bureau codes: 0 - clear or a few clouds, 1 - partly cloudy (scattered), 2 - cloudy, 4 - fog or smoke, 5 - drizzle, 7 - snow, 8 - showers. A FEW PRACTICAL HINTS: If there is snow on the ground wear waterproof boots. Dress in layers and bring 2 more layers than you think you could possibly need. Bring Chapstick. A pocketful of "trail mix" can keep your energy and spirits high while walking those boring fields. Two observers can easily survey different blocks using one car by establishing pickup locations along a road at the end of the count. http://www.im.nbs.gov/winter/instruct.html field surveys
Purpose:
GOAL: To survey in a uniform manner the wintering bird life of Maryland. After an initial 6-year survey period, we will develop winter range and relative abundance maps for diurnal wintering birds. In subsequent decades this technique will be used to monitor fluctuations, trends, and cycles in populations. It may also serve to monitor emigrations of unpredictable northern species. The Maryland winter bird survey is to provide an accurate picture of the winter distribution of birds in a region and will work well in areas with high volunteer labor pools.
Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
N: 40.0
S: 38.0
E: -74.0
W: -78.0
Data Set Citation
Dataset Originator/Creator:
Patuxent Wildlife Research Center, Biological Resources Division U.S. Geological Survey ;
Dataset Title:
Maryland Winter Bird Survey
Dataset Release Date:
1994
Dataset Release Place:
Laurel, MD
Dataset Publisher:
PWRC, Inventory and Monitoring Biological Resources Division USGS
Quality
Data has been completely verified to the best of the investigators' abilities. Care should be taken not to over-interpret the edges of the contour divisions on the kriged maps. The edges of boundaries often look "busy" with lots of "squiggles" which should be ignored for the most part. This is due to a choice made in applying the software (e.g., 200-unit grid) ... to make the resulting surface follow the outline of blocks, representing the true area surveyed. Thus, the dot maps should be compared to the contour maps for questionable abundance contours on the contour maps. The dot and contour maps each describe the data from a different perspective and, generally, either the dot map or the contour map is better for any given species, but it will be left to the reader to decide which map is preferred for each species. However, any contour map with an asterisk (*) following the figure number indicates that this map was particularly uninformative, usually because the species was difficult to detect and was missed in parts of its range. For these species, the dot map should be used, not the contour map.
Any contour map with an asterisk (*) following the figure number indicates that this map was particularly uninformative, usually because the species was difficult to detect and was missed in parts of its range. For these species, the dot map should be used, not the contour map.
NASA Goddard Space Flight Center
Global Change Master Directory
City:
Greenbelt
Province or State:
MD
Postal Code:
20771
Country:
USA
Publications/References
Citation Information: Originator: Jeffrey S. Hatfield, Sue A. Ricciardi, Greg A. Gough, Danny Bystrak, Sam Droege, and Chandler S. Robbins Publication Date: 1993 Title: Distribution and Abundance of Birds Wintering in Maryland 1988-1993 Series Information: Series Name: Maryland Birdlife Issue Identification: V. 50, nos. 1-4 Other Citation Details: pp. 3-83 Methodology Citation Information: Series Information: Series Name: Maryland Birdlife Issue Identification: V. 50, nos. 1-4
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