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End of Eurasian Wren Spring Passage Shifted 5.7 Days Earlier Over 60 Years

Eurasian wren perched in vegetation
Research · Ecology

The final phase of Eurasian wren (Troglodytes troglodytes) spring migration through the southern Baltic coast shifted 5.7 days earlier between 1964 and 2023. A 60-year study from the Hel bird-ringing station in northern Poland found no comparable long-term shift in the beginning of passage, while the median date moved 2.2 days earlier without reaching statistical significance.

The study, published on 13 April 2026, examined the dates when 10%, 50% and 90% of the season’s wrens had passed the station. The birds monitored at Hel are mainly from northern and north-eastern breeding populations that move between Fennoscandia, the Baltic region and north-western Russia and wintering areas farther south and west in Europe.

Weather months earlier was linked to migration timing

The researchers compared migration dates with temperature and rainfall during earlier stages of the annual cycle in four regions of Europe. The relationships differed both by region and by phase of migration. The start of passage was earlier after warm winters and springs in central Europe, but later after warm springs in south-western Europe. The median was earlier after warm springs in central Europe and warm autumns in south-western Europe, but later after warm winters in southern Europe. The end was earlier after warm autumns in northern and south-western Europe, but later after warm springs in south-western Europe. The same type of weather therefore did not have one uniform effect across the migration route.

Rainfall showed equally phase-dependent carry-over effects. The start of passage was later after wet autumns in northern Europe and wet springs in southern Europe, but earlier after wet autumns in southern Europe. The median was later after wet winters and springs in central Europe. For the end of passage, wet winters in central Europe and wet late-summer or autumn conditions in northern Europe were linked to later dates. By contrast, wet early summers in northern Europe, wet springs in central Europe and wet winters in south-western Europe were linked to an earlier end, while wet springs in southern Europe delayed it. The authors suggest that some of these differences may reflect regional effects of rainfall on food availability, body condition and the composition of the migrating population.

Carry-over effects span much of Europe

The authors interpret the pattern as evidence that migration timing at the Baltic coast reflects conditions encountered well before the birds arrive there. They suggest that temperature and rainfall can influence food availability, body condition, migration distance and the proportion of young birds in the migrating population, producing carry-over effects that persist across seasons.

Sources and image credit

  1. Gołębiewski, I., & Remisiewicz, M. (2026). Influence of temperature and rainfall on the timing of the spring migration of Eurasian Wren Troglodytes troglodytes through the southern Baltic coast. The European Zoological Journal, 93(1), 542–562. https://doi.org/10.1080/24750263.2026.2645285Primary peer-reviewed study published online 13 April 2026. Ringing data from Hel, northern Poland, covered 1964–2023; the start of spring passage showed no long-term trend, the median shifted non-significantly 2.2 days earlier, and the final phase shifted significantly 5.7 days earlier.

Image: Georgi.petrov66 — Eurasian wren photographed 27 November 2022; Wikimedia Commons; representative species image, not a bird from the Hel ringing study · CC BY-SA 4.0 · Source

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