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CONFERENCE SCHEDULE UPDATES & CHANGES: As a result of the prolonged government shutdown, we experienced a number of cancellations and changes to the schedule. Cancellations and changes are listed here (as of January 26, 2019). 

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Poster [clear filter]
Tuesday, January 29
 

6:00pm EST

(P84) True Metabolizable Energy of Submersed Aquatic Vegetation for Gadwall
AUTHORS. Margaret Gross, Western Illinois University/Illinois Natural History Survey - Forbes Biological Station; Heath Hagy, U.S. Fish & Wildlife Service; Christopher Jacques, Western Illinois University; John Simpson, Winous Point Marsh Conservancy; Sean Jenkins, Western Illinois University; J. Brian Davis, Mississippi State University; Joseph Lancaster, Illinois Natural History Survey - Forbes Biological Station; Aaron Yetter, Illinois Natural History Survey - Forbes Biological Station

ABSTRACT. Wetland vegetation communities provide critical foraging habitat for waterfowl, but many of the historical wetlands in the United States have been lost throughout the last two hundred years. The loss of wetlands has led to substantial declines in submersed aquatic vegetation species, which are important foods of waterfowl and other wildlife. Unfortunately, there is a lack of information about the implications of these losses on energetic carrying capacity for waterfowl, especially ducks. Waterfowl managers typically estimate the energetic carrying capacity for a wetland by using bioenergetics models. These models incorporate several parameters that predict energy demand, including population size, stopover duration, and the energetic value (i.e. true metabolizable energy) of foods available to ducks. Of these parameters, energetic carrying capacity models are especially sensitive to true metabolizable energy values, however, very few true metabolizable energy estimates are available for submersed aquatic vegetation. Most available true metabolizable energy values are from plant seeds and have only been estimated for a couple waterfowl species that do not primarily consume aquatic vegetation. I estimated TME<sub>N</sub> (true metabolizable energy corrected for non-dietary nitrogenous compounds) values of six common species of submersed aquatic vegetation for gadwall in order to parameterize energetic carrying capacity models and better understand the value of emergent marshes for ducks. Vegetation species was the most important predictor of true metabolizable values (mean ± SE; kcal/g[dry]) of submersed aquatic vegetation (Myriophyllum spicatum, 0.77 ± 0.32; Elodea Canadensis, 0.70 ± 0.31; Ceratophyllum demersum, 0.55 ± 0.28; Najas guadalupensis, –0.61 ± 0.34; Vallisneria americana, –0.98 ± 0.39; Stuckenia pectinata, –1.07 ± 0.33), but both sex and mass of birds was also influential.

Tuesday January 29, 2019 6:00pm - 9:00pm EST
SUPERIOR BALLROOM C/D
  Poster, Wetland

6:00pm EST

(P85) Using a Plasma Lipid Metabolite Index to Evaluate Spring Migration Stopover Habitat for Wild Canvasbacks (Aythya valisineria) in Illinois
AUTHORS. Andrew F. Bouton, Western Illinois University; Eric J. Smith, Western Illinois University; Heath M. Hagy, US Fish and Wildlife Service; Michael J. Anteau, US Geological Survey; Randy V. Smith, Illinois Department of Natural Resources; Christopher N. Jacques, Western Illinois University,

ABSTRACT. Wetland loss and degradation in stopover areas can lead to declining food resources, which in turn has implications for migratory waterfowl populations.  The spring condition hypothesis states that migratory stopover areas are vital for acquiring nutrients necessary for nesting and egg production.  Lipid metabolite (i.e., triglyceride [TRIG], beta-hydroxybutyrate [BOHB]) concentrations of blood plasma can provide a useful index of daily mass change in wild birds and can be used to assess forage quality of stopover sites.  We evaluated an index of foraging habitat quality by measuring plasma lipid metabolite levels and daily mass change of wild canvasbacks (Aythya valisineria) held in short-term captivity for feeding (n = 30) and fasting trials (n = 30) on 60 individuals.  We collected two blood samples from each bird (i.e., 0 and 24 hr) and measured metabolite concentrations using established assay procedures.  We tube-fed birds selected for the feeding trial every 4 hours for a 24-hour period and provided only water for fasting birds over the same period.  Respectively, TRIG and BOHB were positively and negatively related to mass change (Results not yet finalized).  Our analysis revealed that sex was not an important predictor of daily mass change.  We used our index to predict changes in lipid reserves of birds collected experimentally from across the Upper Mississippi River and the Illinois River Valleys.  Our analyses indicated that canvasbacks gained weight across the Upper Mississippi River and Illinois River Valley, suggesting that these areas had sufficient forage resources to provide nutrients for canvasbacks during spring migration.

Tuesday January 29, 2019 6:00pm - 9:00pm EST
SUPERIOR BALLROOM C/D
  Poster, Wetland

6:00pm EST

(P86) Using Plasma-lipid Metabolites to Index Mass Changes in Birds: Are Triglycerides More Indicative of Energy Income Than Deposition?
AUTHORS. Eric Smith, Western Illinois University; Michael Anteau, U.S. Geological Survey; Heath Hagy, U.S. Fish & Wildlife Service; Christopher Jacques, Western Illinois University

ABSTRACT. During spring migration, energy acquisition and storage are important for survival during resource-limited periods, endurance flights, and reproduction. Plasma-lipid metabolites (triglyceride [TRIG], β-hydroxybutyrate [BOHB]) have been used to index changes in lipid reserves over short-time periods, thus have utility for assessing foraging habitat quality at stopover sites. However, such an index may be affected by energetic maintenance costs and further validation under experimental conditions is needed to understand potential sources of variation. We evaluated a previous index using wild lesser scaup (Aythya affinis; hereafter scaup) held in short-term captivity (24 hr) during spring migration through Illinois, USA. β-hydroxybutyrate was negatively associated and TRIG was positively associated with changes in body mass (R<sup>2</sup> = 0.68). Our BOHB slope estimate was nearly identical to one published previously on free-living scaup. However, effects of TRIG differed from free-living scaup and varied by sex, with females having a greater slope. Our results suggest that TRIG is a better measure of energy income than deposition because TRIG slopes appear to be sensitive to energetic maintenance costs. In contrast, BOHB appears to be reliable in predicting negative mass change which is consistent with previous findings. Despite differences in TRIG slopes, our cross-validation process using z-standardized predictions from captive and free-living scaup corresponded well and there was no directional bias (r<sup>2</sup> = 0.79). Sexual differences in apparent lipid deposition rates warrant further research before a generalizable model is advisable for comparing mass change predictions across studies. However, if predictions are standardized it appears this technique is generally robust to variations in energy income vs. deposition. Our evaluation provides verification for the utility of plasma-lipid metabolites as an indicator of short-term mass change and as a potential index of foraging habitat quality.

Tuesday January 29, 2019 6:00pm - 9:00pm EST
SUPERIOR BALLROOM C/D
  Poster, Wetland