Study
Tracking Long-Distance Songbird Migration by Using Geolocators
Stutchbury, Bridget J. M.; Tarof, Scott A.; Done, Tyler; Gow, Elizabeth; Kramer, Patrick M.; Tautin, John; Fox, James W.; Afanasyev, Vsevolod
Science, 2009
Miniature light-level geolocators were fitted to two songbird species small enough that satellite tags were impossible, and recovered on return the following breeding season.
- Studied in
- Progne subis, Hylocichla mustelina
- Sample size
- purple martins and wood thrushes carrying 1.5 g geolocators
Birds travelled far faster on spring migration than existing estimates assumed, with individual daily rates several times higher than had been inferred from ringing recoveries.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Direct tracking of small songbirds is feasible, and the resulting picture of migration speed differs substantially from what indirect methods implied.
How NatureHQ reads it
The record for how a method changes an answer. Ringing recoveries could only ever say that a bird was here and later there; the interval between was assumed. When it became measurable, the assumption turned out to be wrong — and NatureHQ uses this to explain why tracking method belongs in a migration statement rather than being left out of it.
- Geolocators must be recovered, which biases the sample towards survivors that returned to the same site.
- Positional accuracy is coarse, and unusable around the equinoxes.
- Two species, one flyway.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Bird migration
Arctic terns travel further in a year than any known animal — but not in a straight line. The tracked route wanders, pauses in the mid-Atlantic for weeks, and is far longer than the gap between its ends.
How we know where animals go
What is known about where animals go is mostly a story about batteries. Every time tags got smaller, a new set of species became answerable — which is why we know far more about a swan than a swift.
How we know where animals go
A geolocator stores light levels and transmits nothing. To learn anything you have to catch the same bird again the following year — so every route measured this way comes from a bird that survived.
Published by: American Association for the Advancement of SciencePublished in Science or Science Advances (AAAS).
doi.org/10.1126/science.1166664
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.