Research Updates
Migratory Connectivity of Louisiana Waterthrush and Worm-eating Warbler
The Ruhl lab just wrapped up a research collaboration with ornithologists from University of Tennessee, Tennessee River Gorge Trust, and University of Toledo working to investigate the migration ecology and range-wide migratory connectivity of Louisiana Waterthrush and Worm-eating Warbler. Click HERE to read about the migration of these two species!
Migration of Cerulean Warblers
The Ruhl lab is teaming up with the Sam Shine Foundation to document the migratory routes, stopover hotspots, and stationary non-breeding grounds locations for Cerulean Warblers that breed within the Southern Indiana Cerulean Warbler Birdscape (SICWB) geography. Cerulean Warblers are listed as state endangered in Indiana. This species, like many other neotropical migrant songbirds, spends the majority of the year in South America. This means that habitat management on the breeding grounds alone is not sufficient to protect and conserve this species. We must also map migratory connectivity for the Indiana breeding population in order to fill this critical knowledge gap and inform international conservation efforts.
Undergraduate Research Students
Elisa González Dalton Kidder Fallon Hale Mason Adams
Lucy Floyd Amanda McNeill Rebecca Stephens Abby Howell
Non-breeding ecology of North American sparrow species is an important research focus of full annual cycle conservation for White-throated Sparrows, which are considered "short-distance" migrants. Thanks to decades of observational studies, we have a pretty solid understanding of diurnal habitat use and foraging preferences for most species, but roosting ecology and habitat selection remains an elusive knowledge gap. In January and February, my students use radio-telemetry methods to determine roosting habitat preferences and spatial distributions of overwintering White-throated sparrows. They also aim to address questions related to behavioral topics related to thermoregulation, communal roosting, and social dominance hierarchies.
Elizabeth Nojd
White-throated Sparrows have an expansive non-breeding range distribution, spanning most of the Eastern United States. As a result, it is likely that habitat associations and roosting behaviors may vary regionally. Our previous research described the roosting ecology of birds that overwintered in Arkansas, but this winter we will track birds at study sites in Indiana and Louisiana to determine whether temperature and vegetation structure impact roosting behavior differently at the latitudinal extremes of the non-breeding range. Stay tuned for results from this exciting new project!
This research project is a collaboration between Purdue University and Louisiana State University
Karena Barlow Hannah Adams Aric McKinney
Optimal foraging theory predicts that organisms should make foraging decisions that maximize net energetic gain. In 2020 and 2021, Karena, Hannah, and Aric used radio frequency identification (RFID) technology to determine whether the foraging preferences of Tufted Titmice (Baeolophus bicolor) matched the predictions of optimal foraging models in situ. We tested two prey items (whole sunflower seeds and sunflower kernels) to assess the predictions of optimal foraging cost-benefit models in an experiment in which the energetic currency of food was kept constant, but handling time differed. Our results from this study were published in 2023!
Dr. Ruhl's Graduate Research at Purdue University
Ph.D.
I conducted my Ph.D. research in the Dunning Lab of the Forestry and Natural Resources Department at Purdue University. During the summer (May 31-Aug 15), I mist-netted and banded birds in the clearcuts of the Hardwood Ecosystem Experiment (HEE). The HEE is a 100-year landscape-level study monitoring the social and ecological impacts of forest management within the Morgan-Monroe and Yellowwood State Forests in southern Indiana. My project focused specifically on the association of mature forest birds with early successional habitat during the postfledging period. Neotropical migrants that require large tracts of mature forest for breeding and nesting, such as Worm-eating Warbler, Ovenbird, Wood Thrush, and Scarlet Tanager often move into early successional habitat during the postfledging period (the time between nesting and migration). Although there are several hypotheses to explain this behavior, the driving factors behind species-specific habitat association during this time remain largely unknown. I used a variety of techniques (e.g., constant-effort mist-netting, stable isotope analysis, and radiotelemetry) to address these habitat use questions.
M.S.
I completed my Masters research in the Purdue University Forestry and Natural Resources Department in 2014. My research focused on the effects of intensive biomass harvest for bioenergy on eastern red-backed salamanders in Jennings county, Indiana. Plethodontids have been suggested as an ideal bio-indicator species for forest ecosystems. Because they are considered to be a surrogate for forest ecosystem health, I monitored the abundance of Eastern red-backed salamanders in response to a gradient of 0-100% retained coarse woody debris (CWD) following timber and biomass harvesting. I also considered key aspects of salamander health such as standard metabolic rate and body condition. CWD was a significant predictor of salamander abundance. However, I was not able to identify a threshold of resilience for plethodontids based on the gradient of retained CWD. This study emphasizes the need for future wildlife research on biomass harvesting to ensure appropriate implementation of regulations that provide better protection of the integrity and biodiversity in forest ecosystems.
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