On birds, behavior, and the power of observation
Along the western coasts of Central and South America lives a bird with bright baby-blue feet. Compared to the rest of its body, the bird’s feet are big and floppy, and stand in stark contrast to its coffee brown wings and white-gray plumage.
The male aptly-named blue-footed booby uses its webbed beauties to attract females. Once he approaches, he displays each foot, one at a time. As he displays, he rocks back and forth, performing a slow, ritualistic dance. Every few steps, he extends his wings in full, still while rocking back and forth, showing off his feet. If the female is interested, she will join him by displaying her feet, one at a time, back and forth, until both birds are almost in synchrony – back and forth, rocking.
Sydney Hope witnessed this courtship sway while visiting the Galápagos Islands in 2011 after her freshman year in college. Crouched on a nearby rock, she watched the birds’ movements, one foot at a time, back and forth. The display fascinated her. She began to wonder how this unique mating behavior evolved.
By then an undergraduate studying biology, Sydney was attuned to observing wildlife. Ever since she could remember, she had loved watching and playing with animals. Now, she was bearing witness to life in the wild, and making connections between her coursework and her interest in animal behavior. Her thinking grew from an innate, personal curiosity to an observation-driven exploration.
Since then, she has applied the same fascination with the blue-footed boobies to other species of birds, including the Carolina chickadee, the Oregon junco, and most recently the wood duck – all while asking questions about her observations: why do these animals behave this way, and how do they benefit from such behaviors?
With this deep sense of curiosity and questioning, Sydney began graduate school at Virginia Tech in the fall of 2014. As a Hokie, she studies wood duck behavior and physiology under the mentorship of Bill Hopkins, professor of fish and wildlife conservation in the College of Natural Resources and Environment, a Fralin Life Science Institute affiliate, and director of the Global Change Center at Virginia Tech.
For her master’s research, which is funded by a prestigious National Science Foundation Graduate Research Fellowship, Sydney investigates how the wood duck’s early nesting environment affects its ability to perform certain behaviors important for survival.
Wood ducks typically nest in trees, she explained. The nest itself is in a deep cavity below the opening in the truck where the ducks come and go. Once a baby wood duckling hatches, it uses the claws on its webbed feet and the momentum of its hopping body to climb up to the opening and jump out. Accomplishing this feat during the first day of life is critical to early survival.
“This is my favorite wood duck behavior,” said Sydney. “Most of the time the nest is over water, so they jump into the water. But I’ve heard stories that they can nest in cities over concrete. When they jump, the ducklings fall to the ground, bounce up to three feet in the air, and then are perfectly fine!”
The duckling’s exit is usually motivated by its mother, who whistles for them to join the rest of the family. So, in addition to behaviors like jumping out of nests, Sydney observes and measures behaviors related to a duckling’s degree of sociality, like how much and when a duckling vocalizes or ‘calls’. She also observes how they interact with the world around them, including their movement patterns and their responses to stimuli like others’ vocalizations.
Investigating how behaviors like these change due to different environmental conditions during development is important because they can affect the wood ducklings’ ability to survive. Sydney focuses on how small changes in incubation temperature of the eggs impact the ducklings once they hatch and grow.
Changes in incubation temperature may be due to a number of factors, Sydney explained, including the amount of time the mother sits on the eggs, and whether other wood ducks have laid eggs in the same nest, increasing the nest size. Furthermore, anything that disrupts maternal wood duck behavior during incubation can affect the incubation temperature. Human disturbances, for example, can scare an incubating wood duck mother off a nest. In addition, climate change may result in more extreme weather events and varying food availability, which would force a mother to spend more time foraging and less time incubating. Both scenarios would cause a decrease in incubation temperature, which could be detrimental to proper development of the young.
Ultimately, Sydney plans to compare behavior and incubation temperature to blood levels of hormones and the brain receptors for those hormones in order to reveal the biological mechanisms underlying these behavioral patterns. Learning more about how early developmental biology and behaviors later in life correlate will help Sydney continue her quest for answers to tough but important questions – and we all have the blue-footed boobies to thank.