Impact of Long Piers on Birds in Worcester County

1. The Effect of Long Piers on Birds Using Marsh Habitat in Worcester County, Maryland Alison E. Banning, Jacob L. Bowman,Bruce L. Vasilas University of Delaware January 22, 2007 Jake Bowman

2. Tidal Salt Marsh Functions Erosion Control Storm Buffer Wildlife Habitat Water Filtration Fish & Crustacean Nursery Aesthetics Jacob Bowman

3. Birds of the Salt Marsh Obligate Marshbirds Facultative Marshbirds Swamp Sparrow Boat-tailed Grackle Red-winged Blackbird Virginia Rail Fish Crow Sharp-tailed Saltmarsh Sparrow Willet Kevin T. Karlson Gulls & Terns Herons & Egrets Tri-colored Heron Great Egret Harold Linstrom Common Tern Great Black-backed Gull Mark Bashita Black-crowned Night-heron Jacob Bowman

4. Introduction • High rate of development and population increase • 70% of county residents live within the Coastal Bays Watershed • 5-10 million visitors annually • Continued pressure on coastal systems

5. Introduction • Long piers ≥100 ft. • Permitting regulations • Current moratorium on long pier permitting • Are birds using marsh habitat being impacted by the presence of long piers? • Contribution of surrounding habitat? • Birds as an indicator of marsh health

6. Study Objectives • Determine the effect of long piers over marshes on bird a. abundance by bird group • species richness by group, by species

7. Study Objectives • Determine the effect of landuse variables on bird a. relative abundance b. species richness determined by surrounding marsh area, human development, agriculture, forest, long piers, and road cover

8. Study Area • Long pier sites and control sites (no-pier) paired locally • 500m survey site spacing • 200m no-pier buffer around control sites • Survey sites on private and public land • Site distribution follows county development Chincoteague Bay Atlantic Ocean

9. Site Selection 224 long piers (with and without marsh) 22 Long Pier Sites 24 Control Sites (No-Pier)

10. Site Selection Pier site example Control site example

11. Methods Bird Surveys • 2005-2006: Pier sites: n=38, Control sites: n=34 • Standardized North American Marsh Bird Monitoring Protocols (C. Conway 2004) • 15 minute bird surveys targeting birds <50m • 4 replications per site, May-July • Sunrise & sunset with tide & weather considerations Digitizing • 2004 MDE aerial photographs • 5 landuse categories • MDE road files to measure length (km) • # long piers • Tabulated landuse within 500m, 1000m and 5000m buffers

12. Analysis Using 4 bird groups: Obligate marshbirds, Facultative Marshbirds, Herons & Egrets, Gulls & Terns • Relative Abundance • between site types • to long pier density • with landuse variables at 3 buffer levels • Species richness • between site types • to long pier density • With landuse variables at 3 buffer levels

13. Analysis • Treatment sites & habitat variables • vegetation, open water and mudflat coverage between pier and control sites • Treatment types and landuse variables • Compare pier and control values • 6 variables at 3 buffer sizes

14. Results: Obligate Marshbirds • Relative Abundance • Less abundant at pier sites; P=0.005 • Willets more abundant at control sites; P=0.039 • Close to negative interaction with long pier density; P=0.060 • Increased with area of marsh within 500m, P=0.0001 & 1000m, P=0.001 • Decreased with area of agriculture within 5000m; P=0.005 • Species richness • Lower at pier sites; P=0.002 • Negative interaction with long pier density; P=0.005 • Increased with area of marsh within 500m, P=<.0001 and 1000m, P=0.001 • Decreased with amount of agriculture and long piers at 5000m; P=0.003

15. Results: Facultative Marshbirds • Relative Abundance • Negative interaction with long pier density; P=0.014, Increased with amount of agriculture within 500m, P=0.003, and 1000m, P=0.002 • Species richness • Decreased with area of marsh within 5000m, P=<.038

16. Results: Herons & Egrets • Relative Abundance • Greater abundance at pier sites; P=0.023 • Positive interaction with long pier density; P=0.0003 • Decreased with area of agriculture and marsh within 1000m, P=0.004, and 5000m; P<0.0001 • Species richness • Greater at pier sites; P=0.019 • Decreased with amount of agriculture at 500m, P=0.018 and agriculture and marsh at 1000m, P=0.0003, and 5000m; P<0.0001

17. Results: Gulls & Terns • Relative Abundance • Species richness • Increased with long pier density, P=0.026

18. Results: treatment sites & habitat variables 0.004 0.004 0.405 0.662 0.486 0.598 0.803 0.219 0.627 0.618 0.367 0.375 α< 0.05

19. Results: Treatment types & Landuse variables α< 0.05

20. Discussion • Marsh specialists are most sensitive to long piers and long pier density. • Positive interaction with marsh area • Negative with agriculture • Facultative marshbirds are sensitive to long pier density • Agriculture relationship for food • Herons and Egrets benefit by long piers and pier density • Sensitivity to humans • Perching, especially for juveniles • Foraging • Gulls and terns least effected • Increase with pier density and open water foraging and diet flexibility

21. Discussion: Landscape Analysis • Marsh area and Long Piers: clumped human development and pier construction • Habitat differences: high/low marsh ratios, alteration with construction, effect on marsh functions • Development pressure and economic gain • Wetland loss and sea level rise • Pier regulations for new construction, replacement, community piers vs. private

22. Acknowledgements Funding provided by:Academic Support: Dr. Greg ShriverField Assistants: Erin Cord Anna Joy Lehmicke

23. Questions and Comments Further information: abanning@udel.edu (302) 831-8884