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Autumn Movement Timing Stayed Stable as Wings Became Rounder in Great and Eurasian Blue Tits

A great tit and a Eurasian blue tit perched on the same tree stump
Research · Ecology

Twenty-one years of ringing data from Hungary show that the timing of post-breeding autumn movements remained broadly stable in great tits (Parus major) and Eurasian blue tits (Cyanistes caeruleus), even as their average body mass and wing structure changed. The study analysed 43,898 captures from three ringing stations between 2004 and 2024.

The researchers separated the August dispersal period from the main movement period in September and October and examined different age and sex groups. Across the long time series, neither species showed a consistent shift toward earlier or later autumn movement.

August body mass and wing length declined

Body measurements changed more clearly. During August, average body mass and wing length declined over the study period in both species. The authors suggest that warming in the Carpathian Basin may have favoured smaller-bodied birds in the Hungarian breeding populations, but this remains an interpretation of the long-term pattern rather than a direct test of climate as the cause.

During September and October, changes varied among age and sex groups and did not fit one simple body-size response to warming. One broader pattern was more consistent: average wing length decreased while the third primary, one of the main flight feathers, became longer. The authors interpret this combination as a shift toward a rounder wing shape.

Rounder wings may point to shorter movements

Wing shape is linked to flight strategy. More pointed wings generally suit sustained long-distance flight, while rounder wings can favour manoeuvrability and shorter movements. The researchers therefore suggest that the changing wing shape could reflect a growing proportion of short-distance movers or shorter average movement distances. Ringing measurements alone cannot show how far individual birds actually travelled.

Great tits and Eurasian blue tits are partial migrants: some individuals remain relatively close to their breeding areas while others disperse or move regionally. The study therefore points to a quieter long-term change than a shift in the calendar itself—stable autumn timing alongside lighter birds and altered wing morphology. Recoveries and tracking data will be needed to test whether the morphological change is actually linked to shorter journeys.

Sources and image credit

  1. Recent changes in migration dynamics, body mass, and wing morphology of the Eurasian Blue Tit and Great Tit during the post-fledging season in Hungary

Image: caroline legg — Great Tit (Parus major) and Eurasian Blue Tit (Cyanistes caeruleus) in Dumfries and Galloway, Scotland, photographed 11 November 2023; Wikimedia Commons/Flickr. Representative species image, not birds from the Hungarian study. CC BY 2.0. · CC BY 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Ecology

SPECIES IN THIS STORY

Species in this story

Great Tit Parus major Explore species Eurasian Blue Tit Cyanistes caeruleus Explore species

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