Influences of Drawdown on Waterbird Use of Mudflats in Kentucky Reservoir. Kentucky Reservoir INVERTEBRATES AND MOIST-SOIL SOIL SEEDS

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1 Influences of Drawdown on Waterbird Use of Mudflats in Kentucky Reservoir Drew W. Wirwa, Matthew J. Gray, T. Hill Henry, and Robert M. Wheat Kentucky Reservoir INVERTERATES AND MOIST-SOIL SOIL SEEDS 1

2 Kentucky Reservoir Flood Prevention Hydroelectric Power Production Navigation Recreation geosynthetica.net Reservoir Management Prior to 198 drawdown initiated in June; mudflats exposed mid-july 198 drawdown delayed until July 5, mudflats exposed mid-august August September October Recent legislation delay drawdown until after Labor Day Reservoir Operations Study (ROS) Reservoir Operation Studytudy Regional Assessment and Management of Inland Stopover Habitats for Shorebirds in the Tennessee River Valley What shorebird species migrate through the valley, and in what numbers? When do they migrate through? Where do shorebirds stopover in the Valley? How does TVA management of the river system affect stopover habitats? 2

3 TVA - ROS John Laux,, 28 Comparison of two east Tennessee reservoirs at different drawdown n dates Preliminary Results drawdown date shorebird use is significantly affected by August August October Study Site Kentucky Reservoir 9 Sites etween US Hwy- 79 and I-4 I Eagle Creek Study Sites Scan each mudflat 2X/week Permanent survey point etween sunrise and 5 hrs after sunrise Swarovski 2-6x Methods August December 26/27 3

4 Methods 6x 6x 6x Survey Point Statistical Analysis Among Months (27) Test: Repeated Measures ANOVA Mean Richness Among Months (27) Test: Repeated Measures ANOVA % Composition Among Months (26/27) Test: Chi Square Test of Homogeneity *shorebirds and waterfowl Water Level and Shorebird Total Daily Abundance Correlation Test: Pearson Correlation; Least-squares squares Regression All tests performed at α =.5 using SAS system Shorebird p =.9 No Difference etween Months 4

5 Shorebird (excluding Killdeer) A A September > October, November, December p.5 Waterfowl p = No Difference etween Months Shorebird Mean Richness Mean Richness A September > all other months p.1 5

6 7 6 Waterfowl Mean Richness No Difference etween Months p =.3 Mean Richness percent composition 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Richness (S) Shorebird Species Composition 26/27 Combined p.1 S total = 26 8% 8% 3% 11% 35% Aug Sept Oct Nov Dec Total Shorebirds n = 23,779 16% 33% 26% 21% 6% 1% 11% 74% 7% 8% 84% WRSA WIPH WILL WESA STSA SPSA SOSA SESA SEPL SDO SAND RUTU PIPL PESA LEYE LESA LDO KILL GRYE DUNL COSN SA PL ASA AMGP AMAV Most Common - Killdeer n = 12,375 52% Clayton Ferrell (USFWS) percent composition Shorebird Species Composition 26/27 Combined (excluding Killdeer) 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % p.1 S total = 25 13% 47% 17% 11% 22% 45% 53% 13% Aug Sept Oct Nov Dec Richness (S) Uncommon Species Most Common Least Sandpiper American Total Avocet Shorebirds Ruddy Turnstone n = 4,77 aird s s Sandpiper n = 11,44 Wilson s s Phalarope 41% uff-breasted Sandpiper Willet Piping Plover 8% 4% 28% 31% 71% 21% WRSA WIPH WILL WESA STSA SPSA SOSA SESA SEPL SDO SAND RUTU PIPL PESA LEYE LESA LDO GRYE DUNL COSN SA PL ASA AMGP AMAV 6

7 percent composition 1% 8% 6% 4% 2% % Richness (S) Waterfowl Species Composition 26/27 Combined p.1 S total = 19 9% 33% 53% 16% 73% 15% 38% 3% 23% 21% 14% 14% 14% 19% 4% 4% Aug Sept Oct Nov Dec WODU SNGO RUDU ROGO RNDU REDH NSHO NOPI MALL LESC HOME GWTE GWFG GADW CAGO CACG WTE UFF AMWI ADU Total Waterfowl n = 17,851 Most Common - Gadwall n = 36,882 34% Clayton Ferrell (USFWS) Reservoir Gage Height (ft msl) Correlation of Water Level and Shorebird Abundance 26 7/31 8/14 Summer Pool Winter Pool 8/28 9/11 9/25 Initial Mudflat Exposure 1/9 1/23 11/6 11/2 12/4 12/ Suitable Habitat 2 1 Daily Abundance Gage Pearson Correlation, r = -.42 R 2 =.17 Total Abund Reservoir Gage Height (ft msl) /3 Correlation of Water Level and Shorebird Abundance 27 8/16 Summer Pool 9/3 9/2 1/8 1/25 11/12 11/29 12/18 Winter Pool Daily Abundance Gage Total Abund Initial Mudflat Exposure Pearson Correlation, r = -.36 R 2 =.13 7

8 Migration Temperature Hunting Pressure Available Habitat Mudflat acreage at a given lake elevation Microhabitat Factors Soil moisture/compaction Soil Temperature Food Availability Vegetation Response Potential Mechanisms Influencing Results Influencing Factors Mudflat acreage Invertebrate Abundance Soil Temperature Soil compaction Soil Moisture Vegetation Hunting pressure Future Analysis Time Series Identifying the nature of a phenomenon (i.e., migration) represented by the sequence of observations Acknowledgements Tennessee Valley Authority (TVA) United States Fish and Wildlife Service (USFWS) University of Tennessee Knoxville Department of Forestry, Wildlife and Fisheries Tennessee Wildlife Resources Agency (TWRA) 8

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