Red-billed Tropicbirds breeding on Pilot Hill on the island of Sint Eustatius have been exhibiting an average survival rate of between 30-40%. The influence of nest cavity attributes, environmental covariates, and parent behavior on Red-billed Tropicbird survival were evaluated through nest surveys and camera trap data. Daily survival rate was calculated as a function of selected covariates. Time spent away from the nest by parents and minimum temperature were the most influential factors. Nest attributes and temperature variables did not correlate to survival.
[Picture]
Red-billed Tropicbird chick (~3-4 weeks) monitered on Pilot Hill, Sint Eustatius, 2022. Photograph by Hailley Danielson-Owczynsky
[Picture]
Presentation of master thesis research at Science Cafe CNSI, May 2022. Photograph by Hannah Madden.
Weekly Nest Surveys & Camera Traps
Every week, the Red-billed Tropicbirds breeding on Pilot Hill, Sint Eustatius, are surveyed. Adults are carefully extracted from the nest and their unique identification band is recorded. Additionally, the presence of any egg or chick is recorded. After a chick hatches, they are checked and weighed each week. When they are grown enough, they also receive their own unique identification band. Red-billed Tropicbirds raise one chick per year and invest a huge amount of time and energy to raising the chicks.
[Picture]
Ringing an adult Red-billed Tropicbird on Pilot Hill, Sint Eustatius (all handling and ringing was conducted under license). Photograph by Hailley Danielson-Owcznsky
[Picture]
Checking a juvenile (yellow bill) Tropicbird that is almost ready to fledge. Photographer unknown
[Picture]
A recently hatched chick, tucked into a highly sheltered nest cavity. photograph by Hailley Danielson-Owczynsky
Parental Infanticide Red-billed Tropicbirds
[Picture]
Camera trap photo, evidence of suspected infanticide. Photograph by Hailley Danielson-Owczynsky, Reconyx camera trap
During the project where I was investigating factors that influence the breeding success of Red-billed Tropicbirds on Pilot Hill, I found what appeared to be evidence of a parent destroying its own egg. This was totally unexpected and while trying to understand why the bird might have done this, we decided it would be a benefit to the body of research surrounding Red-billed Tropicbird breeding ecology to have this information published.