Sara is a female green turtle, Chelonia mydas. She weighs 80 kilos and her shell measures 96 centimetres along the curve. A satellite transmitter glued to her carapace followed her for 418 days around San Cristóbal, in the Galápagos. Ninety-eight per cent of her locations fall near that island. The rest come from Santiago.
Sara belongs to a group of nine adult turtles, seven males and two females, tagged between August 2015 and November 2018 on four islands: Española, Floreana, Isabela and San Cristóbal. The study was published on 27 August 2026 in Frontiers in Amphibian and Reptile Science. The first author is Juan Pablo Muñoz-Pérez, of the University of the Sunshine Coast in Australia and the Universidad San Francisco de Quito. The corresponding author is John Rowe, of Alma College in the United States. The other seven authors work in Ecuador, Singapore, Mexico, Costa Rica and the United States.

Two forms of green turtle live in the Galápagos. The black morphotype is the typical eastern Pacific form. The yellow morphotype is paler and, by one hypothesis, has affinities with Indo-Pacific populations. Recent genomic studies indicate that the two forms are differentiated. Almost nothing was known about how the yellow form moves.
The tags talk to the Argos satellite system, which locates the animal each time it surfaces. The locations were processed with a density estimate that draws the outline containing 95 per cent of positions. That is the home range. The 50 per cent outline marks the core area, where the animal spends half its time. Core areas are often small and lie in shallow water close to shore.

None of the nine left the archipelago. Five kept to a single island. Four moved between islands, over tens of kilometres, mostly between April and October. Mike, a male from Isabela tracked for 324 days, used 23.9 square kilometres. Ainoa, a female tracked for only 45 days, ranged across San Cristóbal, Santa Cruz and Isabela over 27,316 square kilometres. Body size does not explain the differences.
The paper gives the mean home range as 1,497.9 square kilometres, plus or minus 2,913.9. That figure is the home range of Cristian, a male from Española. It is the median of the nine values, the one in the middle. The mean of the values in the table is 4,272.9. The plus-or-minus matches the standard error of the mean, not the standard deviation. For the core area the mean, 863.8, is right, and the plus-or-minus is again the standard error. The Frontiers press release speaks of an average home range of about 1,498 square kilometres and repeats the wrong figure.

The release has two more inaccuracies. It quotes the corresponding author as saying no turtle left the reserve over the «three years of our study». Tagging was spread over three years, but no animal was tracked for more than 418 days, and two for fewer than a hundred. It also says three turtles moved between islands. The paper counts four.
The authors list their limitations. Argos has coarse spatial resolution and can inflate home ranges compared with GPS. Tracking may not cover a full breeding cycle if the yellow morphotype migrates at multi-year intervals. El Niño and La Niña effects were not examined, and the sample is small. The raw data will be made available by the authors on request, but have not been deposited.

The practical conclusion concerns the reserve, which together with the archipelago’s other protected waters covers nearly 200,000 square kilometres. For this form the coastline of several islands matters. The core areas lie close to shore. The authors declare no competing interests and state that no generative artificial intelligence was used in writing the paper.

References
Muñoz-Pérez J. P., Alarcón-Ruales D. E., Tanabe L. K., Hart C. E., Heidemeyer M., Steiner T., Arauz R., Valle C. A., Rowe J. W., "Movements of yellow-morphotype green turtles (Chelonia mydas) in the Galápagos Marine Reserve", Frontiers in Amphibian and Reptile Science, 4, 1837921, 27 August 2026, open access. doi: 10.3389/famrs.2026.1837921
Frontiers, press release reproduced by ScienceDaily, "Scientists expected these Galápagos sea turtles to wander. They stayed put", 28 September 2026 (used as a lead and for the errors noted in the text).