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https://hdl.handle.net/11681/46611Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.author | Lott, Casey A. | en_US |
| dc.contributor.author | Wiley, Robert L. | en_US |
| dc.creator | American Bird Conservancy | en_US |
| dc.creator | David Miller Associates | en_US |
| dc.creator | Environmental Laboratory (U.S.) | en_US |
| dc.date.accessioned | 2023-03-17T13:35:30Z | en_US |
| dc.date.available | 2023-03-17T13:35:30Z | en_US |
| dc.date.issued | 2012-12 | en_US |
| dc.identifier.govdoc | ERDC/EL CR-12-4 | en_US |
| dc.identifier.uri | https://hdl.handle.net/11681/46611 | en_US |
| dc.description | Contract Report | en_US |
| dc.description.abstract | This report describes Least Tern (Sternula antillarum) sandbar nesting habitat (SNH) on the Arkansas River below Keystone Dam from field and GIS measurements after the 2008 nesting season. This season was preceded by 2 years with high-magnitude, long-duration dam releases (>50,000 cfs for >3 weeks), which resulted in major habitat renewal; replacing small, low-elevation sandbars that were mostly covered with vegetation with large, completely bare, high-elevation sandbars. Habitat measurements are reported relative to hydrographs that describe Keystone Dam operations for hydropower production and flood control (based on a post-dam era of 1977-2008). Habitat measurements for 2008-2009 were compared to a degraded habitat dataset that was simulated in ArcGIS based on descriptions in the most recent USFWS biological opinion for the Arkansas River. TernCOLONY, an individual-based model of Least Tern reproduction, was then used to evaluate how dam operations affect ILT reproduction, given these two sets of habitat conditions, across the range of dam operations. In simulations, infrequent nest flooding mortality was observed when habitat conditions were outstanding (e.g., after the high flows of 2007-2008). Conversely, regular nest mortality due to flooding, as well as higher predation rates, resulted in low reproductive success when habitat conditions were degraded. Given this baseline understanding, three different management alternatives were simulated that were designed to reduce flooding and/or predator mortality when habitat conditions are degraded (e.g., mechanical sandbar habitat restoration, predator control, and a combination of the two). Only management treatments that included predator control components were effective at increasing regional reproductive output. Since ILT populations experience periods with excellent habitat conditions and degraded habitat conditions at the decadal scales that affect population trajectories, widespread application of this type of evaluation would be helpful to assess the persistence of regional ILT populations considered important to the ILT metapopulation. | en_US |
| dc.description.sponsorship | United States. Army. Corps of Engineers | en_US |
| dc.description.tableofcontents | Abstract ................................................................................................................................................... ii Figures and Tables .................................................................................................................................. v Preface .................................................................................................................................................. viii Unit Conversion Factors ........................................................................................................................ix 1 Introduction ..................................................................................................................................... 1 Background .............................................................................................................................. 1 Objectives ................................................................................................................................. 4 Approach ................................................................................................................................... 5 Least Tern population ecology on regulated rivers ................................................................. 6 A general definition of ILT sandbar nesting habitat (SNH) ..................................................... 7 Drawing inferences from SNH measurements ....................................................................... 8 A specific definition of SNH ..................................................................................................... 9 Contexts for the interpretation of habitat measurements ................................................... 11 2 Defining Sandbar Nesting Habitat Relative to Operational Hydrographs ............................. 14 Defining the ILT breeding season .......................................................................................... 14 Classifying breeding seasons to water year types ................................................................ 15 Relating annual hydrographs to long-term habitat change .................................................. 19 Choosing appropriate flow metrics for data summary ......................................................... 19 Fundamental hydrograph types for evaluating the effects of dams on Least Tern reproduction ........................................................................................................................... 22 Within-day flow variation due to hydropower releases ......................................................... 22 Patterns of within-day flow variability related to hydropower generation ............................... 22 How daily stage variation affects sandbar exposure ............................................................... 23 Effects of daily stage variation on sandbar erosion and plant establishment ....................... 26 Downstream travel of hydropower releases and waterline flow interpolation ....................... 27 High releases/flows during the breeding season that flood nests or chicks ...................... 29 Periods of flooding mortality risk within the Least Tern breeding season .............................. 29 Reproduction-limiting flows ....................................................................................................... 30 Linking hydrographs and habitat measurements .................................................................... 30 3 Methods ......................................................................................................................................... 33 Study area ............................................................................................................................... 33 Hydrologic data methods ....................................................................................................... 35 Field and GIS habitat measurements ................................................................................... 35 Estimating acreage of SNH at different flows ....................................................................... 36 SNH acreage summaries ....................................................................................................... 36 Acreage summaries at benchmark flows ................................................................................. 36 Summarizing key SNH quality covariates ................................................................................. 37 Seasonal availability of SNH ...................................................................................................... 37 Individual sandbar exposure across whole Least Tern nesting attempts ............................... 37 Simulating the effects of nest and chick flooding, habitat restoration, and predator management on tern populations in TernCOLONY ............................................... 38 TernCOLONY simulation experiments ................................................................................... 40 Experiment 1: Nest and chick flooding in the absence of predators/ORVs ........................... 40 Experiment 2: Nest and chick flooding with predators/ORVs present ................................... 41 Experiment 3:Effectiveness of habitat restoration and predator control when habitat conditions are degraded ............................................................................................... 42 Statistical analyses of simulation experiment results .......................................................... 42 4 Results: Habitat Measurements ................................................................................................. 44 Acres of SNH at peak hydropower flows of 13,000 cfs ........................................................ 44 SNH exposure at different benchmark flows ........................................................................ 44 Seasonal exposure of suitable SNH acres (variation among years) ................................... 46 Continuous exposure of SNH during ILT reproduction (summary by water year type) .......... 48 Sandbar habitat quality ......................................................................................................... 51 Sandbar vegetation .................................................................................................................... 51 Distance to the bank/active channel margin ........................................................................... 53 Distance to large trees ............................................................................................................... 53 Distance to low vegetation on sandbars ................................................................................... 53 Freeboard relative to sandbar water surface elevations at 13,000 cfs ................................. 54 5 Results: TernCOLONY Model Simulations .................................................................................. 55 Flooding mortality in the absence of predators/ORVs (Experiment 1) ............................... 55 Flooding mortality when predators/ORVs are present (Experiment 2) ............................... 58 Comparison of management treatments (Experiment 3) .................................................... 68 6 Discussion ..................................................................................................................................... 71 Evaluating the effects of dam operations on ILT reproduction ............................................ 71 Summary of findings .............................................................................................................. 71 Under what conditions might direct management for ILT populations be necessary? .............................................................................................................................. 73 The need to measure SNH after habitat-renewal events as well as when habitat conditions are degraded ........................................................................................................ 74 Conclusions ............................................................................................................................ 75 References ............................................................................................................................................ 77 Appendix A: Hydrologic Data Summary and Analysis Methods ..................................................... 81 Appendix B: Habitat Measurement Methods ................................................................................... 87 Report Documentation Page | en_US |
| dc.format.extent | 111 pages/3 MBs | en_US |
| dc.format.medium | PDF/A | en_US |
| dc.language.iso | en_US | en_US |
| dc.publisher | Engineer Research and Development Center (U.S.) | en_US |
| dc.relation.ispartofseries | Contract Report (Environmental Laboratory (Engineer Research and Development Center)) ; no. ERDC/EL CR-12-4 | en_US |
| dc.rights | Approved for public release; distribution is unlimited | en_US |
| dc.source | This Digital Resources was created in Microsoft Word and Adobe Acrobat | en_US |
| dc.subject | Arkansas River | en_US |
| dc.subject | Interior Least Tern | en_US |
| dc.subject | Keystone Lake (Okla.) | en_US |
| dc.subject | Least Tern | en_US |
| dc.subject | Nest mortality | en_US |
| dc.subject | Sandbar nesting habitat | en_US |
| dc.subject | TernCOLONY | en_US |
| dc.title | Effects of Dam Operations on Least Tern Nesting Habitat and Reproductive Success below Keystone Dam on the Arkansas River | en_US |
| dc.type | Report | en_US |
| Appears in Collections: | Contract Report | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ERDC-EL-CR-12-4.pdf | Contract Report (Environmental Laboratory (Engineer Research and Development Center)) ; no. ERDC/EL CR-12-4 | 3.08 MB | Adobe PDF |  View/Open |