Ultralight Solar Transmitter Enables Fine-Scale Movement Ecology in North American Hummingbird Migration

Abstract Due to attachment weight limitations, animals under 5g have remained a major methodological barrier in movement ecology, limiting tracking options for many small-bodied organisms. We developed and field-tested an ultra-light solar powered transmitter (BlūMorpho 0.058-0.060g) designed to enable continuous, near real-time tracking using a broad, crowd sourced network. We validated the system on two North American hummingbird species during spring migration, demonstrating reliable detection, multi-week retention, broad spatial coverage (United States, Mexico and Canada), and long-distance migration paths including a 6,526km cumulative track. Our results highlight the ability to track the smallest of species across the full migratory range with fine-scale spatial resolution and high temporal resolution using the BlūMorpho transmitter. Importantly, we present the first migratory tracks known to exist on North American hummingbird species. Data/Code for peer review statements R Code used for all analyses is attached for peer review.