Date of Award
Spring 5-10-2025
Document Type
Honors Thesis
Department/Major
Biology
First Advisor
Dr. David Swanson
Second Advisor
Dr. Jacob Kerby
Third Advisor
Dr. Daniel Soluk
Keywords
Least Tern, foraging habitat, Missouri River, wetland sites, off-river foraging
Subject Categories
Animal Sciences | Life Sciences | Ornithology
Abstract
The Interior Least Tern, a summer nesting species native to the sandbars of the Missouri River, faces significant loss of foraging habitat and forage fish populations as a result of modern river regulation. Alternative foraging sites may be located several kilometers from tern nesting colonies at either on-river or off-river wetland sites. To understand how Least Terns use available foraging habitat, we conducted population surveys along the 59-mile reach of the Missouri National Recreational River (MNRR) in Southeastern South Dakota. We conducted land-based surveys at nine on-river public-access sites along the Missouri River and 12 off-river wetland sites within 30 km of the Missouri River approximately weekly during the nesting season. Least Terns consistently occurred in high numbers at all on-river sites. We also observed Least Terns frequenting eight of the 12 off-river sites up to 22 km from the river, including flooded sites appearing part-way through the survey period. These data were collected during the summer nesting period of 2024 as a second-year continuation of the surveys conducted by Boyko (2024) during the 2023 nesting period, thus allowing for comparisons between results from 2023 and 2024. The systematic documentation of Least Tern off-river foraging is an essential first step in understanding the importance of off-river foraging to tern time and energy budgets. This project demonstrates the resilience of the species to declining prey resources and indicates that off-river habitats should also be considered in Least Tern conservation planning.
Recommended Citation
Donelan, Zoe D., "Wandering From The River: On- And Off-River Abundance Of Interior Least Terns Along The 59-Mile Reach Of The Missouri National Recreational River" (2025). Honors Thesis. 398.
https://red.library.usd.edu/honors-thesis/398