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GPS Tracks and Wind Modelling Suggest Black-winged Stilts May Fly Above 7,000 Metres

Two black-winged stilts flying over water
Research · Behaviour

GPS tracks and atmospheric modelling suggest that migrating black-winged stilts (Himantopus himantopus) may sometimes use air layers between about 2,000 and 7,200 metres above sea level. The proposed altitudes were not measured directly, but inferred by comparing the birds’ ground speeds with wind conditions at different heights.

Researchers tracked one female and one male fitted with GPS loggers at a breeding wetland in southern Mallorca. The female wintered near the lower Senegal River, while the male travelled to the Inner Niger Delta in Mali. Both returned to Mallorca the following spring.

Both birds made rapid long-distance migrations

The autumn journeys covered about 3,158 kilometres for the female and 2,624 kilometres for the male, each over five days. The female later travelled more than 2,800 kilometres during the first 48 hours of her spring migration. The tracks were dominated by long, rapid movements with few stops, a pattern the authors describe as a “jumping” migration strategy.

Tailwinds were consistent with possible high-altitude flight

Several track segments had ground speeds above the species’ estimated maximum range speed of 50 kilometres per hour—the calculated airspeed expected to maximise distance travelled per unit of energy. The researchers compared these segments with vertical wind profiles from the ERA5 atmospheric reanalysis, a reconstruction of past atmospheric conditions that combines weather observations with a numerical weather model. Stronger supporting tailwinds at middle and high atmospheric levels could explain the observed speeds and were consistent with possible flight at 2,000–7,200 metres.

The GPS units did not record altitude, and the authors stress that the estimates therefore require cautious interpretation. Segments compatible with middle- to high-altitude wind assistance made up only a limited part of the migrations, so any use of these layers appears episodic rather than dominant. Direct altitude measurements from more birds are needed to establish how often black-winged stilts use high-level winds. The study nevertheless suggests that adjusting flight height may help migrants exploit tailwinds and reduce the energetic cost of migration.

Sources and image credit

  1. Migratory performance and potential high-altitude flight in Black-winged Stilt inferred from GPS tracking and atmospheric modellingPrimary peer-reviewed open-access research article by Garcias, Perelló, Muñoz, Romero and Pinya Fernández in Avocetta. Originally published 15 July 2026; version 2, updated 10 September 2026, corrected the abstract and the order, number and affiliations of authors. Used for the two GPS tracks, migratory routes and speeds, ERA5 wind analysis, inferred altitude range and the authors’ stated uncertainty.

Image: Two black-winged stilts flying over water. Photo: Charles J. Sharp / Wikimedia Commons. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY-SA 4.0 · Source

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