A lightweight backpack harness for tracking hummingbirds

Hummingbirds and other lightweight bird species are challenging to track
because they have limited capacity to carry devices for data-logging. We
present a simple and customizable three-loop ‘backpack’ harness for
studying hummingbird migration and movement, with step-by-step
instructions for harness construction and attachment. The harness has
negligible weight and cost (< $0.50 USD/each), is easy for a single
person to make and apply in the field, and it requires no complicated
setup or equipment. We have field-tested this harness on 74 Giant
Hummingbirds (Patagona gigas) with three different types of tracking
devices (geolocators, GPS tags, and satellite transmitters) in Chile and
Peru from 2017–2020. Based on recaptures to date, we report that harnesses
last at least two years, even under high UV-light conditions. We found no
evidence of adverse effects of the harnesses on birds after one to two
years and apparent survival of geolocator-tracked Giant Hummingbirds was
in line with published estimates for other hummingbird species. This
harness method is a practical and effective option for mounting
ultra-light devices on hummingbirds, and it can be readily modified for
other species with short legs, prominent sternal keels, and long wings.