Conservation and Ecology of Birds – Waterfowl II

Contributed Paper
ROOM: Room 10 – Anasazi

10:30AM Spring Migration Strategies of Mallards and American Black Duck That Winter in the Finger Lakes Region
Justin M. Droke; Michael Schummer; Jonathan Cohen
ABSTRACT American Black Ducks (Anas rubripes; hereon Black Ducks) were once the most abundant waterfowl in eastern North America, but declined in the last century with concurrent increases in Mallards (Anas platyrhynchos). Mallards are habitat generalist relative to Black Ducks and habitat change to eastern forests may favor Mallards. Competition and interactions between Black Ducks and Mallards have been studied extensively during the breeding season, but spring migration has received much less attention. We investigated habitat selection and foraging behaviors of Black Ducks and Mallards in the Montezuma Wetlands Complex in central New York, March – April 2016 and 2017. The Montezuma Wetlands Complex is the initial spring staging area for Black Ducks and Mallards wintering in the Finger Lakes region of central New York. We also tracked spring migration chronology of female Black Ducks (n = 42) and Mallards (n = 33) marked with GPS/GSM backpack transmitters in the Finger Lakes region, January – March 2016 and 2017. Our study is the first to simultaneously mark female Black Ducks and Mallards on a wintering area where they are sympatric to estimate how they migrate and settle on breeding territories. In 2016, Mallards spent 36% less time feeding and 12% more time resting and preening than Black Ducks in flooded agricultural habitats, whereas behaviors did not differ among other habitat types. On average, Mallards departed the Montezuma Wetlands Complex 26 days earlier than Black Ducks. Most Mallards settling locally on breeding areas before Black Ducks began departing for breeding areas farther north. By September, we will have updated these preliminary 2016 results with 2017 data and provide an assessment of spring habitat use, behaviors, and migration chronology of Black Ducks and Mallards that winter in the Finger Lakes region of central New York.
10:50AM Using Camera Technology to Validate Waterfowl Nest Monitoring Protocols
Sam R. Krohn; John Palarski; Nickolas Conrad; Ryann Cressey; Kaylan Carrlson; Tom Buhl; Susan Ellis-Felege
Waterfowl nesting in the prairies of North America have been well studied, yet little research has been done to validate protocols for fating nests that are commonly used to assess causes of nest failure. To gain a better understanding of nest predators at waterfowl nests (e.g., blue-winged teal (Anas discors) and mallard (Anas platyrhynchos)), we installed a continuously recording video-surveillance system at a subset of nests (n=45/year) at Ducks Unlimited’s Coteau Ranch and The Nature Conservancy’s Davis Ranch near Denhoff, North Dakota during the 2016 and 2017 breeding seasons. Specifically, we aimed to identify the predators of waterfowl nests and to determine if common protocols established by Sargent et al. (1998) were effective for identifying nest predators. We monitored nests until hatch or failure and reviewed video to confirm fate of the nest and in the event of failure, identified the cause. We recorded evidence of depredation in the field using descriptive categories of egg, nest, and habitat characteristics defined by Sargeant et al. (1998). We input this evidence into the Sargeant et al. (1998) model to determine possible predators. We compared video evidence to the model predictors based on signs that remained at the nest to see if we could properly identify the predator. Our comparison of video evidence to standard protocol revealed that protocol database was correct 46% of the time, incorrect 29% of the time, and inconclusive 25% of the time. Information from this study will be used to guide future protocols for determining causes of nest failures at waterfowl nesting in the Prairie Pothole Region.
11:10AM Impacts of Spatiotemporal Variation in Migration Chronology on the Fall Inventory of Midcontinent White-Fronted Geese
Douglas C. Osborne; Ryan J. Askren
Midcontinent white-fronted geese (Anser albifrons) stage in large numbers in Prairie Canada during fall migration to obtain energetics needed to reach the wintering grounds. Since 1990, an annual survey, the fall aerial inventory has been conducted in the region to count the number of white-fronts. Our study aimed to assess migration chronology and proportion of the population counted by the inventory. We deployed satellite transmitters on nonbreeding and failed nesting white-fronts (n = 10) in the Nunavut, Canada during 2014 and on nesting female white-fronts on the North Slope of Alaska during 2014 (n = 4) and 2015 (n = 11). Mean departure date from molting areas in the Canadian Arctic (3 September ± 1.8 days) was 7.9 days earlier than Alaska white-fronts (12 September ± 1.9 days). Mean arrival date of Nunavut white-fronts to the fall staging area (7 September ± 0.6 days) was on average 11 days earlier than Alaska white-fronts (18 September ± 2.5 days). During 2014, 100% of white-fronts marked in the Nunavut were located within the survey area during the survey period, whereas only 50.0% (2014) and 77.8% (2015) of white-fronts from Alaska occurred in the survey area during the survey period, respectfully. Trends of count data from fall inventory guide regulatory frameworks and harvest management strategies in the Central and Mississippi Flyways, however our data suggest the fall inventory may be missing a large portion of breeding adult and hatch-year white-fronts from the North Slope of Alaska. We suggest evaluating the fall inventory sampling design to include a framework that would allow for statistical estimation of population abundance, inclusion of a second survey period to capture late migrating white-fronts including the primary breeding stock, or consider alternative approaches to informing harvest management strategies.
11:30AM From Bluebills to Bivalves: Lesser Scaup Diets and Population Trends on Lake Pontchartrain
Clay M. Stroud; Kevin M. Ringelman; Michael A. Poirrier; Claire E. Caputo
Lake Pontchartrain provides wintering habitat for a continentally-significant proportion of Lesser Scaup (Aythya affinis). Mid-winter surveys indicate dramatic variation in annual scaup abundance (221–1,194,907), though the mechanisms driving these fluctuations are unknown. Previous studies indicate that scaup feed primarily on mollusks, and so changes in the benthic community (species composition, abundance, and size classes) have the potential to influence scaup dynamics on the lake. Benthic communities are in turn shaped by hurricanes, droughts, and spillway openings, potentially creating a lagged bottom-up trophic cascade that ultimately affects scaup populations. To diagnose trophic linkages and variation in scaup abundance, we collected ducks and paired benthic samples (n=60) from the field to evaluate diet preferences, and then used this information to guide analysis of pre-existing long-term datasets on scaup and benthic populations. The most common prey species was Rangia cuneata, accounting for 43.49% of all food items. Compared to 2004 (255 individuals/m2), R. cuneata practically disappeared from the lake in the winter of 2005 due to Hurricane Katrina (31 individuals/m2), but rebounded to above pre-Katrina levels (384 individuals/m2) the following year. Likewise, there were less than 500 scaup estimated in the winter of 2005, but over 800,000 birds the following winter. Droughts and spillway openings produced similar patterns of immediate decline in R. cuneata and scaup abundances with increased populations the following year. These disturbances appear to reset the size-class succession of benthic invertebrates; the intervening periods were characterized by an increasing abundance of larger bivalves, and accordingly fewer scaup. Scaup populations on Lake Pontchartrain appear to be closely linked to R. cuneata populations, which are affected by disturbance events that alter salinity and water quality. Our results provide valuable information on trophic linkages in an estuarine system that is particularly prone to increasingly frequent disturbance events predicted with climate change.
11:50AM Variables Influencing the Wintering Distribution of Black Scoters in the South Atlantic
Hannah M. Plumpton; Emily D. Silverman; Beth E. Ross
Along the Atlantic coast of the United States there has been an increase in human activity. These activities include energy production, sand mining, aquaculture, shipping, and coastal development that all have the potential to greatly impact sea ducks throughout their migratory cycle. Of the sea ducks wintering along the Atlantic coast the black scoter (Melanitta americana) has the largest and most variable range, encountering the effects of global change throughout migration. To better quantify the abundance and wintering distribution of black scoters and other sea ducks, the U.S. Fish and Wildlife Service conducted aerial surveys from 2009-2012 along the Atlantic coast. Initial results showed that the core wintering areas used by black scoters varied each year and that black scoters could be found as far north as the Boston Harbor and as far south as the Georgia coast. We build on this previous work to further describe the species distribution during winter and assess the factors influencing their annual distribution using the data from the U.S. Fish and Wildlife Service winter surveys. We discuss and identify several key habitat variables including the ocean depth, substrate type, and distance from shore. Our top model had quadratic functions for the variables distance to shore (11.26 ± 1.67 SE) and ocean floor slope (-4.48 ± 1.83). The results from our model showed that black scoters were primarily found within the first 3 miles from the shore and with an ocean floor slope of 0 to 0.1 degrees. The results from this study will increase knowledge on the wintering ecology of black scoters and aid in the development of future aerial surveys to better quantify abundance, as well as identifying areas of potential overlap with energy development.


Contributed Paper
Location: Albuquerque Convention Center Date: September 27, 2017 Time: 10:30 am - 12:10 pm