DOI: 10.5061/dryad.6m905qgbs
title: Decline of salt marsh-nesting birds within the lower Chesapeake Bay (1992-2021)

description: 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.
description: Plots were considered for inclusion if they were dominated
 (&gt;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.
description: # Decline of salt marsh-nesting birds within the lower Chesapeake Bay
 (1992-2021) Dataset DOI:
 [10.5061/dryad.6m905qgbs](10.5061/dryad.6m905qgbs) **Principal
 Investigators**:   Bryan D. Watts, [bdwatt@wm.edu](mailto:bdwatt@wm.edu),
 757-221-2247  **Data Administrator**:   Marie Pitts,
 [mlpitts@wm.edu](mailto: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 (&gt;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%,
 &gt;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/](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/](https://scholarworks.wm.edu/ccb_reports/486/)