Beau A. Bauer, M.S. student, Nemours Wildlife Foundation and James C. Kennedy Waterfowl and Wetlands Conservation Center, Clemson University
Wetland Management for Widgeongrass and Aquatic Invertebrate Biomass in South Carolina Tidal Coastal Impoundments
Abstract: Widgeongrass (Ruppia maritima) is a cosmopolitan submersed aquatic vegetation (SAV) of brackish wetlands. Management of SAV species is practiced in impounded tidal wetlands (i.e., historic rice fields) in coastal South Carolina to provide forage for waterfowl and other waterbirds. Widgeongrass also provides habitat and associated periphytic forage for aquatic invertebrates. I conducted an experiment to test effects of complete drawdown to dried substrate versus partial, shallow water (1 – 10 cm) drawdown for 7-14 days for each treatment during May – June 2016 on aquatic invertebrate and SAV biomasses in managed brackish tidal impoundments (MTI) in the Ashepoo, Combahee, and Edisto Rivers Basin, South Carolina. Such data were lacking to inform managers of best management practices to promote standing crops of SAV and aquatic invertebrates. I sampled sediments and SAV in 20 MTIs (10 complete and 10 partial drawdown MTIs) and three natural tidal marsh sites (control) during August 2016, November 2016, January 2017, and April 2017. I used general linear model analysis of variance to test (α = 0.10) effects of drawdown on SAV biomass (g[dry]/m2) and effects of drawdown and control tidal marsh on benthic invertebrate biomass (g[dry]/m2). Control marshes lacked SAV, so only benthic invertebrates in sediments could be sampled in tidal wetlands. I also used general linear model analysis of covariance to test (α = 0.10) effects of drawdowns and SAV (covariate) on combined benthic and epifaunal invertebrate biomass—the latter of which inhabited widgeongrass. I detected a treatment effect of drawdown and the control marsh on SAV biomass for August 2016 (P = 0.012) and on benthic invertebrate biomass for these treatments for all sampling periods (0.021 P 0.079). I detected a significant positive effect of SAV biomass during November 2016, January 2017, and April 2017 (0.001 P 0.086), and drawdown treatments on total invertebrate biomass for August 2016, November 2016, and April 2017 (0.018 P 0.045). The SAV covariate was removed for August 2016 total invertebrate biomass analysis due to collinearity with drawdown treatment effect. Benthic and total invertebrate and SAV biomasses were greatest in partially drawndown MTIs. The exception to this pattern was that benthic invertebrate biomass was greater in both partially and completely drawndown MTIs than natural tidal marsh in January 2017. My results suggest that both drawdown management practices and SAV biomass influence variation in total invertebrate biomass in sampled MTIs—with SAV biomass being a more temporally consistent influence than treatment alone. Total invertebrate and SAV biomass production peaked in August 2016 before Hurricane Matthew devastated SAV communities in October 2016. This result and that total invertebrate and SAV biomasses were greatest in partially drawndown MTIs suggest that partial drawdowns may maximize invertebrate and SAV biomasses and MTI foraging carrying capacities for late summer-fall migrating ducks and other waterbirds in coastal South Carolina. However, I also recommend periodic complete drawdowns to consolidate flocculent soils and decompose organics to promote rooting by SAV. I will complete my study in 2018 and plan to graduate in December 2018 or May 2019.
Gillie Croft, M.S. student, Nemours Wildlife Foundation and James C. Kennedy Waterfowl and Wetlands Conservation Center, Clemson University, Yemassee and Clemson, SC USA
Wood and Other Duck Use, Selection, and Production in Nest Structures in Coastal South Carolina
Abstract: We conducted a landscape-scale survey of nest-structure use and production by wood ducks (Aix sponsa), black-bellied whistling ducks (Dendrocygna autumnalis), and hooded mergansers (Lophodytes cucullatus) in coastal South Carolina during 2016-2017. We modeled effects of box volume, entrance size and height above ground or water, and micro-habitat features on selection of nest boxes by wood ducks and black-bellied whistling ducks. For 364 and 354 nest boxes surveyed in both years (n = 718 box years), 66% were used by waterfowl and disproportionately among species (wood ducks 61%, black-bellied whistling ducks 15%, and hooded mergansers 0.3%). Wood ducks nested from January-August ( = 181-day nesting season) with peak nesting in March-May. Black-bellied whistling ducks nested from May-September ( = 116-day nesting season) with peak nesting in June-July. Internal volume of 364 boxes in our study ranged between 15,190.23 cm3 and 40,818.96 cm3. Wood ducks were 5.8% (β = −0.00006, SE = 0.00002, P = 0.0032, n = 718) more likely to select nest boxes for every 1,000 cm3 decrease in internal volume. However, black-bellied whistling ducks were 18.8% (β = 0.00017, SE = 0.000044, P = 0.0001, n = 718) more likely to select nest boxes for every 1,000 cm3 increase in internal volume. Canopy cover above the box had a negative association with nest box selection, and boxes were 15.2% (β = −0.01646, SE = 0.00285, P < 0.0001, n = 718) and 11.3% (β = −0.00199, SE = 0.00526, P = 0.0232, n = 718) more likely to be selected by wood ducks and black-bellied whistling ducks for every 10% decrease in percent canopy cover. Additionally, nest boxes were 18.1% (β = 0.01661, SE = 0.005978, P = 0.0058, n = 718) and 10% (β = −0.01053, SE = 0.00362, P = 0.0038, n = 718) more likely to be selected by black-bellied whistling ducks for every 10 cm increase in distance from base of box entrance vertically to ground or water surface and every 10 m decrease in distance between boxes. Based on egg-shell membranes recovered in structures (i.e., an index of successfully hatched egg), an estimated 3,378 wood duck, 531 black-bellied whistling duck, and 19 hooded merganser ducklings exited nest structures over both years of study for an average of approximately six ducklings across species per box (n = 3,928 ducklings/718 boxes; = 5.5 ducklings). We suggest when initiating a nest box program where wood ducks and black-bellied whistling ducks nest sympatrically, internal volume and entrance size of boxes should be constructed to accommodate both species. Our data suggest the conventional nest box described by Bellrose (1980), with internal volume of 34,375 cm3 and internal dimensions of 25 × 25 × 55 cm adequately accommodated both wood ducks and black-bellied whistling ducks, and therefore can be deployed where both species occur. However, we suggest nest box entrances be constructed to have 12.7 cm diameters to facilitate use by black-bellied whistling ducks and maintain use by wood ducks. Additionally, we found ducks selected boxes in generally open areas and often in ponds with predatory fish, which could create “ecological traps” if ducklings are depredated by fish or other predators. We emphasize the importance of proper nest-box placement near suitable brood-rearing habitat (e.g., shoreline scrub-shrubs) to promote duckling survival and recruitment. Our study did not estimate brood survival and duckling recruitment into fall and breeding population nor cost benefits. Therefore, we emphasize need to determine recruitment by box-nesting females of cavity nesting waterfowl in North America.
Nicholas M. Masto, M.S. Student Fellow, James C. Kennedy Waterfowl & Wetlands Conservation Center and Clemson University, Georgetown and Clemson, SC, USA
Aerial Strip–Transect Surveys to Estimate Fall–Winter Abundance and Distribution of Waterfowl and Other Waterbirds in South Carolina
Abstract: Aerial surveys for waterfowl and other waterbirds are essential for estimating and monitoring population size and trends, respectively, and determining habitat relationships and spatiotemporal distributions of these birds. Researchers have designed aerial surveys that provide precise estimates of breeding and wintering populations of ducks and other waterfowl over large physiographic regions; yet, few state conservation agencies have adopted statistically rigorous surveys. In response to cessation of the Midwinter Waterfowl Survey by the U.S. Fish and Wildlife Service in 2016 and need for reliable probability based surveys of wintering waterfowl and other waterbirds, we designed and implemented an aerial survey to estimate abundance of eight groups of waterbirds including dabbling ducks (tribe Anatini), diving ducks (tribes Aythini, Mergini, and Oxyurini), total ducks, geese and swans (tribes Anserini and Cygnini), coots and gallinules (Rallidae), pelagic and piscivorous waterbirds (Anhinga spp., Larus, Pelacanus, and Phalacrocorax species), raptors (subfamily Circinae, Haliaeetus leucocephalus, and Pandion haliaetus) and wading birds (families Ardeidae, Threskiornithidae, and Mycteria americana) in coastal and inland regions of South Carolina. We sampled fixed width transects across 7.5–10% areal coverage of strata in South Carolina and used design-based analyses to estimate waterbird population indices (Î; abundance not corrected for imperfect detection) for four surveys during fall 2017–winter 2018. We also evaluated differences in estimates by front- and rear-seat aerial observers for January and February 2018 surveys. Estimates met our a priori goal of precision (CV ≤ 15–20%) during February for three waterbird groups (i.e., diving ducks and pelagic waterbirds for the front-seat observer and coots and gallinules for the rear-seat observer). The greatest abundance of total ducks was observed in January 2018 by front- and rear-seat observers (Î = 74,504, CV = 32%; Î = 113,936, CV = 28%, respectively) and the greatest summed abundance of all waterbirds observed by front-seat observer was in November 2017 (Î = 141,163). Front- and rear-seat observers’ estimates differed for pelagic waterbirds (z0.005 = −2.75, P = 0.0061) and diving ducks (z0.005 = −2.59, P = 0.0096) in January and February 2018 surveys, respectively. Pooled estimates met our a priori goal of precision for pelagic waterbirds in January and February 2018 surveys and diving ducks in February 2018. Probabilistic sampling enabled interpolation and graphic depiction of waterbird densities across survey strata, which can be used to monitor seasonal spatial distributions, inform managers and the public of high- and low-use areas, and target areas for future habitat conservation and hunting opportunity. I will conduct analyses to determine increased level of sampling needed to improve precision in future surveys. Despite variability in survey estimates exceeding our a priori goal of precision for most groups of birds, our aerial transect surveys of fall and wintering waterbird populations are the only statistically rigorous waterbird surveys being conducted currently in South Carolina and, to our knowledge, other Atlantic Flyway states inland of the Atlantic Ocean
Lauren H. R. Senn, Ph.D. Student Fellow, James C. Kennedy Waterfowl and Wetlands Conservation Center, Clemson University, Clemson, SC USA
Development, Assessment, and Marketing an Online University Course in Waterfowl Ecology and Management
Abstract: To our knowledge, only Clemson University currently offers an online course in Waterfowl Ecology and Management available to undergraduates and graduate students. Such a course is needed especially by wildlife students and professionals unable to matriculate to campuses where this course remains offered. As part of my dissertation research, Dr. Rick Kaminski and I have converted his Waterfowl Ecology and Management course from traditional face to face lecture and laboratory to online presentation, and I will be evaluating the transition, students’ opinions, and marketing of the new online course. We offered the online course for the first time in fall 2017, as an elective in Clemson University’s new online Master’s degree in Wildlife and Fisheries Biology. The conversion process involved video recording lecture material, using online software to transcribe the audio of each lecture, pairing transcribed video and audio with corresponding lecture slides, and re-recording audio to match videoed lectures. We wrote a script for hundreds of slides, enabling students to read text after listening to it narrated. The course is split into nine learning modules: History of Waterfowl Conservation, Waterfowl Morphology and Identification, Habitat Use and Selection, Evolutionary Ecology Related to Waterfowl, Annual Cycle Ecology and Management (Fall/Winter, Vernal [Spring Migration], Reproduction, Post-breeding/Molting), Adaptive Harvest Management (by Dr. Beth Ross, USGS South Carolina Cooperative Fish and Wildlife Research Unit, Clemson University), and Waterfowl Diseases. Each module also includes readings on current research, a class discussion, and quiz. Students are evaluated via module quizzes, a group oral presentation, a waterfowl identification exam, and midterm and final exams. To earn graduate credit, graduate students propose a research project that is approved by Dr. Kaminski, and they submit a research proposal to him written in the style of a scientific journal article. The course will be assessed each semester by evaluations submitted by enrolled students. The initial fall 2017 offering of Waterfowl Ecology and Management had an enrollment of 11 undergraduate and 14 graduate students. All students received a grade of A, B, or C. Post-course survey results indicated that 93% of the students believed the course increased their knowledge and appreciation of waterfowl and they would recommend the course to others, and 87% of respondents stated that lecture videos were effective in helping them assimilate course material. Results also showed a need for improvement in the group presentation component of the course, with 73% of respondents either reporting ‘neutral’ or they believed the project was ‘somewhat effective’ in helping them learn course material. Results of these surveys will provide insight on strategies for improvement of the course, and development of best practices for converting similar wildlife science and management courses to an online format. Course improvements include updating the group presentation so it is better integrated into an online format, as well as the addition of a knowledge assessment test to be given to each student at the start and end of the course. In addition to work on the course, I will be collaborating with Drs. Shari Rodriguez and Kaminski on a survey to be administered to attendees of the 8th North American Duck Symposium in Winnipeg, Manitoba, Canada, August 2019. The survey will be designed to profile demographics and professional characteristics of attendees to help determine what credentials and experiences promote becoming a waterfowl and wetlands professional.