Waterfowl

Contributed Paper
ROOM: CC, Room 19
SESSION NUMBER: 47
 

1:10PM Building a Model of Submerged Aquatic Vegetation for Atlantic Brant in the Mid-Atlantic Using Remote Sensing and In-Situ Sampling
Chase Colmorgen
With a constantly changing environment, the ability to retain and protect submerged aquatic vegetation (SAV: eelgrass (Zostera marina), widgeongrass (Ruppia maritima), and macroalgae (Ulva sp., Entermorpha sp, Gracilaria tikvahiae, and assorted Rhodophyta) is becoming more important as they provide critical ecosystem functions. SAV has many benefits to organisms including the Atlantic brant (Branta bernicula hrota) which is a specialist on these food sources. For example, after a stark decrease in eelgrass in the early 1930s due to a wasting disease from the slime mold Labyrintha zosterae, the population of Atlantic brant also decreased due to lack of food availability. With eelgrass never fully recovering, the brant substituted macroalgae as an alternative food source within a few years. Today, brant populations are still fluctuating raising questions as to whether current food abundance is a factor in their population changes. Thus, building a predictive model of SAV abundance will aid in predicting the potential carrying capacity of wintering brant within the Atlantic flyway. We used Landsat 8 imagery to create a Normalized Difference Vegetation Index (NDVI) of SAV between Long Island and Southern New Jersey which coincides with the highest population wintering grounds for brant. We collected water depth, quality, turbidity, salinity, and SAV biomass at 257 1m2 quadrats across the study area including 174 predicted SAV points and 82 null points. All SAV samples are identified to species, cleaned, dried, and weighed to determine energy density availability. Akaike Information Criterion (AIC) values showed models containing salinity, water depth, and NH3-N are significant drivers of SAV presence. The NDVI results revealed higher modeling accuracy for algae species than seagrass, but also supports the theory of more algae abundance than seagrass. These modeling results coupled with the sorted biomass values allow estimations for wintering brant carrying capacity across the Mid-Atlantic.
1:30PM Nest Site Selection of Boreal Ducks at Multiple Spatial Scales
Matt Dyson; Brad Fedy; Stuart Slattery; Jim Devries
Predator-prey relationships shape ecological communities and play a prominent role in shaping species life history strategies. Land use change can have profound effects on predator-prey interactions, and threaten both predator and prey population persistence. In many avian species, nest success is critical to population performance. Therefore, species are under intense selective pressure in choosing a safe nest site when predation is the primary cause of nest failure. The western boreal forest (WBF) supports 12 – 15 million ducks annually, second only to the Canadian Prairies. However, we have limited knowledge of duck nesting ecology in the region including information about the diverse assemblage of potential nest predators, and interactions with the changing landscape. We investigated ground-nesting duck nest site selection in the WBF of Alberta across multiple scales. We located 109 duck nests in 2016 and 2017. We used regression approaches to identify micro (4th order) and macro (3rd order) scale habitat features selected by ducks. At the micro-scale, females selected nest sites that provided greater overhead cover and higher percent forb, grass, and shrub composition compared to random locations. However, birds also selected nest sites with less lateral cover. Our results provide evidence of a tradeoff, in which females seem to balance the need for concealment from aerial predators with the need for increased vigilance and escape from terrestrial predators. At the macro-scale, we expect ducks to select for proximity to wetlands and avoid industrial features. Overall, alteration of predator communities in the boreal caused by climate and landscape change may result in maladaptive nest site selection strategies by boreal ducks. Therefore, further investigation of the adaptive significance of nest site selection at multiple spatial scales is warranted for boreal waterfowl conservation and management.
1:50PM Movement Variation of Overwintering Ring-Necked Ducks in the Southern Atlantic Flyway.
Tori D. Mezebish; Mark D. McConnell
Animal movement patterns are influenced by resource distribution and anthropogenic activity. Ring-necked ducks (Aythya collaris) are one of the most abundant and highly harvested North American diving ducks; however, few studies have investigated their overwintering movement patterns. Overwintering movement ecology in relation to hunting disturbance and resource abundance could have implications for harvest regulations and wetland management at multiple scales. We quantified changes in daily movement distances of ring-necked ducks in the Red Hills Region of the southern Atlantic Flyway during the 2017-2018 overwintering season. We calculated average daily step lengths using hidden Markov modeling for eleven satellite transmitter implanted females. Daily distance moved by individuals throughout the total overwintering period was 5.04 km, CI=4.31-5.77. However, daily distance moved was significantly greater during (6.03 km, CI=5.12-6.9) than after hunting season (3.61 km, CI=2.68-4.55). Hunting events may have generated regular escape movements by individuals, causing daily step length to be higher during hunting season than after. Decreased daily distance moved may also be related to changes in available habitat post-hunting season. Many Red Hills managers drain managed wetlands shortly after the waterfowl hunting season ends, reducing regional wetland density. If resources at remaining wetlands were abundant enough to prevent large-scale resource-seeking behavior, ring-neck movements may have decreased to step lengths corresponding to distances between the limited wetlands available. Moreover, this trend may not be directly related to anthropogenic activity, but a function of migratory preparation. Hens likely decreased the magnitude of exploratory movements during the post-hunting overwintering period to energetically prepare for spring migration, and utilized a minimal number of wetlands. Our findings demonstrate a behavioral shift in ring-neck movement ecology that may be related to hunting disturbance and resource distribution. Further research should investigate the roles and magnitude of these factors to better understand overwintering ring-necked duck ecology.
2:10PM Developing a Plasma Lipid Metabolite Index for Canvasbacks
Andrew Bouton; Eric Smith; Heath Hagy; Michael Anteau; Randy Smith; Chris Jacques
The canvasback (Aythya valisineria) is a wetland-obligate species that is dependent on submerged aquatic vegetation (SAV), namely tubers, moist-soil seeds, and aquatic invertebrates. Since the 1950s, fluctuations in the canvasback population may be due, in part, to changes in wetland quality and abundance at migration stopover sites and wintering areas. Wetland loss and degradation can lead to declining food resources, which in turn has direct implications for migratory waterfowl. Thus, a need to provide high-quality habitat for wetland-obligate species is paramount for management and conservation efforts. As such, a greater understanding of the fate of acquired nutrients (e.g., catabolized or accumulated) as lipid reserves may be useful in assessing habitat quality of key migration stopover areas for large-bodied diving ducks like canvasbacks. Lipid metabolites circulating in the blood plasma can be useful to index daily mass change in wild birds. Studies on small passerines and lesser scaup have shown that plasma lipid metabolites (triglyceride, beta-hydroxybutyrate) can be used to estimate short term mass changes. We developed an index of the relationship between plasma-lipid-metabolite concentrations and daily mass change by capturing canvasbacks on Pool 19 of the Mississippi River and conducting feeding or fasting trials on 60 individuals (15 males and 15 females each) during March 2017. Our index predicted 77% of the variation, with triglycerides being positively correlated and beta-hydroxybutyrate being negatively correlated with mass change (daily mass change = -130.22 + 52.62(TRIG) – 81.17(BOHBln)). Our index can be used to predict changes in lipid reserves of wild canvasbacks and indicate quality of forage at stopover areas.
12:50PM Cinnamon Teal Nest Attendance Influences Nest Survival during Incubation
Casey Setash; William L. Kendall; David Olson
Patterns of nest attendance in birds influence whether or not an individual’s reproductive attempt is successful and have the potential to impact the future success of its offspring. Parental behaviors during incubation vary based on an individual’s body condition, energy requirements, and environmental factors in its breeding habitat. We assessed nest attendance patterns in the cinnamon teal (Spatula cyanoptera) breeding in the San Luis Valley of Colorado from 2016-2017. We evaluated temporal and environmental impacts on the duration and frequency of incubation recesses and the constancy with which a hen incubates. We then assessed their impacts on nest survival during the incubation stage. We observed weak support for a negative relationship between nest initiation date and recess frequency, and recess duration varied by nest age and time of day, with hens on older nests taking longer recesses in the afternoon and hens on nests earlier in incubation taking longer recesses in the morning and evening. Incubation constancy decreased with higher ambient temperatures and increased for hens with older nests. Nest survival was positively associated with lower recess frequency and longer recess duration. Our results suggest cinnamon teal might be modifying their behavior during the breeding season to use variable climatic conditions to their advantage while maintaining the highest probability of a successful reproductive attempt.

 

Contributed Paper
Location: Cleveland CC Date: October 9, 2018 Time: 12:50 pm - 2:30 pm