Laysan Duck (Anas laysanensis) Use of Artificial Freshwater Sources on Midway Atoll
A banded Laysan Duck pair at Monument Guzzler
Radar Seep on Eastern Island with Laysan Ducks
Below Ground Guzzler (Parade Guzzler) on Sand Island. Camera Trap set up seen with solar panel.
A banded Laysan Duck pair at Monument Guzzler
As a part of my fulfillment for my B.S. degree in Wildlife Ecology, I completed a capstone project. With the help of Dr. Amber Roth and Dr. Erik Blomberg, I developed project goals and methods, conducted field work, data collection and analysis, and presented my findings in a research paper and poster.
While on Midway Atoll National Wildlife Refuge with the help of refuge biologists, I set up camera traps at different artificial water source types, groundwater seeps and plastic tubs called guzzlers on both Sand and Eastern Island. I independently reviewed over 8,650 camera trap images to gather the data needed including number of ducks, behaviors observed, and environmental conditions, such as temperature and weather. I also conducted quadrat surveys to determine vegetative habitat. Using R, I analyzed the variation in duck density and behavior through linear models.
Abstract
The Laysan Duck (Anas laysanensis) is a critically endangered species endemic to the Hawaiian archipelago. To facilitate reintroduction on Midway Atoll National Wildlife Refuge, two types of freshwater sources, groundwater seeps and plastic tubs called guzzlers, were constructed. To better guide future management, we evaluated the differences between freshwater sources in terms of duck density, vegetation characteristics, and daily duck behavioral patterns. Photos from camera traps were evaluated to estimate duck density and frequency of behaviors at n = 4 seeps and n = 6 guzzlers. Duck density was higher at guzzlers than seeps (β = -0.41 ± 0.06), increased with higher air temperature (r2 = 0.42), and increased throughout the summer (r2 = 0.43). Density was the highest in the morning (β = 0.02 ± 0.01) and lowest at night (β = -0.09 ± 0.01). Based on quadrat surveys, plant richness (p < 0.05) and diversity (p = 0.01) are higher at seeps, but their effects on duck density was inconclusive. Activity didn’t vary throughout the day, but active ducks were more frequent at guzzlers during the day and night compared to seeps. Higher duck density at guzzlers may be concerning for managers due to the higher risk of conspecific competition, disease transmission, and botulism outbreaks. Maintaining seeps can provide a low-density refuge and a high-quality vegetative habitat.
Poster presented at the Maine Chapter of the Wildlife Society Fall Meeting in Orono, ME in December of 2022.