Decline of salt marsh-nesting birds within the lower Chesapeake Bay (1992-2021)
Data files
Apr 25, 2025 version files 66.71 KB
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Boat-tailed_Grackle.csv
4.86 KB
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Clapper_Rail.csv
5.14 KB
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Eastern_Meadowlark.csv
4.84 KB
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Marsh_Patches.csv
791 B
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Marsh_Wren.csv
4.91 KB
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Point_Locations.csv
7.23 KB
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README.md
3.85 KB
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Red-winged_Blackbird.csv
5 KB
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Saltmarsh_Sparrow.csv
4.92 KB
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Seaside_Sparrow.csv
5.58 KB
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Sedge_Wren.csv
4.81 KB
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Song_Sparrow.csv
4.92 KB
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Virginia_Rail.csv
4.87 KB
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Willet.csv
5.01 KB
Abstract
A survey was conducted of a network of patches (N = 186) within tidal salt marshes located in the lower Chesapeake Bay (1992, 2021) for 12 species of breeding birds to evaluate trends in occupancy and abundance. The data includes 13 tables: Marsh Patch (patch codes and dates), Point Locations, and tables for the 11 surveyed species.
Dataset DOI: 10.5061/dryad.6m905qgbs
Principal Investigators:
Bryan D. Watts, bdwatt@wm.edu, 757-221-2247
Data Administrator:
Marie Pitts, mlpitts@wm.edu, 757-221-7503
Institutional Partners:
The Center for Conservation Biology
William & Mary
Environmental Protection Agency
Description of the data and file structure
A survey was conducted of a network of patches (N = 186) within tidal salt marshes located in the lower Chesapeake Bay (1992, 2021) for 12 species of breeding birds to evaluate trends in occupancy and abundance. Surveys were conducted along the western shore of the lower Chesapeake Bay between Grandview Beach (City of Hampton) and New Point Comfort (Mathews County) in Virginia. Birds were surveyed within 30-m fixed radius plots using a call-response technique. Plots were considered for inclusion if they were dominated (>90%) by and contained all of the plant forms including smooth cordgrass (≥30%), black needlerush (≥20%), salt meadow hay and salt grass combined (≥15%) and groundsel tree (≥10%). Four replicate patches were randomly selected for each size category from a pool of marshes that met criteria.
Files and variables
For the 11 Species Files (file name is species name):
Description: Counts of birds heard or seen during each of the four replicate surveys for each survey point within each marsh patch.
Variables
- Size Category: The percentage of the marsh surface that was included within survey plots declined with increasing patch size (5 ha: 45.0±5.69%, 10 ha: 31.9±1.19%, >65 ha: 9.5 ±1.82%).
- Marsh Code: Unique ID for a marsh patch.
- Point Number: Unique number of a point within a particular marsh patch.
- 1992-1: Number of birds heard in survey 1 in 1992.
- 1992-2: Number of birds heard in survey 2 in 1992.
- 1992-3: Number of birds heard in survey 3 in 1992.
- 1992-4: Number of birds heard in survey 4 in 1992.
- 2021-1: Number of birds heard in survey 1 in 2021.
- 2021-2: Number of birds heard in survey 1 in 2021.
- 2021-3: Number of birds heard in survey 1 in 2021.
- 2021-4: Number of birds heard in survey 1 in 2021.
File: Marsh_Patches.csv
Description: Details about each marsh patch and its survey dates.
Variables
- Marsh Code: Unique ID for each marsh patch.
- Name: Unique name for each marsh patch.
- Size Category: Patch size category.
- Size (ac): Patch size in acres.
- Patch Size (ha): Patch size in hectares
- Round 1: Date of survey 1 in 2021.
- Round 2: Date of survey 2 in 2021.
- Round 3: Date of survey 3 in 2021.
- Round 4: Date of survey 4 in 2021.
File: Point_Locations.csv
Description: Details about each point location within a marsh patch.
Variables
- Size Category: Size category of the patch the point is in.
- Marsh Code: Marsh code of the patch the point is in.
- Point Number: Unique point number within a particular patch.
- Latitude: Latitude in decimal degrees.
- Longitude: Longitude in decimal degrees.
Code/software
Grist CSV Viewer is an open source, in-browser, interactive CSV preview installed with two lines of HTML. https://www.getgrist.com/csv-viewer/
Access information
Other publicly accessible locations of the data:
- n/a
Data was derived from the following sources:
- Watts, B. D. 1992. The influence of marsh size on marsh value for bird communities of the lower Chesapeake Bay. Center for Conservation Biology Technical Report CCBTR-92-01. College of William and Mary, Williamsburg, Virginia. https://scholarworks.wm.edu/ccb_reports/486/
Plots were considered for inclusion if they were dominated (>90%) by and contained all of the plant forms including smooth cordgrass (≥30%), black needlerush (≥20%), salt meadow hay and salt grass combined (≥15%) and groundsel tree (≥10%). Four replicate patches were randomly selected for each size category from a pool of marshes that met criteria.
Birds were surveyed within 30-m fixed radius plots using a call-response technique. The call-response survey consisted of a 5-min sequence of alternating silent listening periods and species recordings in the following order; 1) 30 sec of silence; 2) 50 sec of black rail advertising call; 3) 10 sec of silence; 4) 50 sec of Virginia rail advertising call; 5) 10 sec of silence; 6) 50 sec of clapper rail advertising call; 7) 10 sec of silence; 8) 50 sec of king rail advertising call; 9) 40 sec of silence. Although black and king rails were never detected during either survey period, the playback sequence was maintained for consistency. Counts were executed by standing at the plot center and recording birds seen or heard during the playback sequence.