Biology ETDs

Publication Date

Spring 2026

Abstract

Small body size and rapid metabolism make annual migrations challenging for North American hummingbirds. Many of these birds make annual journeys of over 10,000 km. During migrations, hummingbirds use stopover sites, where they remain for several days to accumulate body fat. At these stopovers, they often encounter uncertainties in food resources, competition, and weather. To save energy, hummingbirds sometimes enter nocturnal torpor. My dissertation uses respirometry data, lipid measurements from Quantitative Magnetic Resonance, and feather hydrogen stable isotopes to understand how energy levels, migration patterns, torpor use, and water balance interact in four species of migrating hummingbirds. I discovered lipid thresholds that elicit torpor and that torpor occurrence and duration are modulated to achieve specific morning fat reserves. I found diverse relationships between migration distance, energetic status, and torpor use. Finally, I quantified water balance in hummingbirds, discovering that they maintain hydric balance at cool temperatures; however, at warmer temperatures, they risk lethal dehydration.

Language

English

Keywords

hummingbird, migration, torpor, metabolism, lipid, water balance

Document Type

Dissertation

Degree Name

Biology

Level of Degree

Doctoral

Department Name

UNM Biology Department

First Committee Member (Chair)

Blair O. Wolf

Second Committee Member

Carlos Martinez del Rio

Third Committee Member

Christopher C. Witt

Fourth Committee Member

Andrew E. McKechnie

Download

Included in

Biology Commons

Share

COinS