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Waxwings, Bullfinches and Redpolls Arrived Earlier in Tatarstan Over 33 Years

Bohemian waxwing feeding on red hawthorn berries
Research · Ecology

A 33-year study of four regular winter guests in Tatarstan found progressively earlier first autumn arrival for three species: Bohemian waxwing (Bombycilla garrulus), Eurasian bullfinch (Pyrrhula pyrrhula) and redpoll (Acanthis flammea). Rough-legged buzzard (Buteo lagopus) showed no clear long-term shift.

A transect is a predefined line or route used to survey an area systematically, with observations, signs or sampling points recorded along it.

The study used first autumn observations from 1991 to 2023 in an area of about 2,200 km² around Kazan. Five permanent transects totalling roughly 70 km were checked several times each week. Arrival dates were compared with May–August temperatures from Kazan and weather stations farther north in European Russia, local autumn temperatures and measures of food availability in Tatarstan.

Two late waxwing records distorted the long-term trend

Two exceptionally late Bohemian waxwing records strongly affected the long-term estimate, so the researchers repeated the analysis without those years. In that analysis, mean first arrival was 14 October and shifted about 0.5 days earlier per year, equivalent to about 16 days across the study period.

Warmer summers were linked to earlier arrival

Mean May–August temperature across the climate stations used in the study increased by about 2.0 °C from 1991 to 2023. For waxwings, bullfinches and redpolls, warmer summers were linked to earlier autumn arrival. For waxwings, the analysis without the two extreme years corresponded to about 3.1 days earlier arrival for each 1 °C increase in summer temperature.

The researchers found no clear relationship with September–October temperature in Tatarstan or with the local food measures they examined. The authors interpret the shared pattern in the three species with earlier arrivals as a shift in autumn phenology associated with warmer summer conditions at higher latitudes.

They propose two ways in which warm breeding seasons could contribute. Earlier spring arrival and breeding can allow the nesting period to finish sooner, potentially permitting earlier autumn departure, while earlier flowering and fruit ripening may allow birds to build migratory reserves sooner. These mechanisms were not measured directly in the Tatarstan study, but form the authors’ explanation for why warmer northern summers were associated with earlier first autumn arrivals.

Sources and image credit

  1. Askeyev, A., Askeyev, O., Askeyev, I., & Sparks, T. H. (2026). Shifts of autumn phenology of ‘winter guest’ birds in deep Eurasia are associated with climate change. Ornithology Research, 34, 5.Primary peer-reviewed article. Published and version of record 27 January 2026.

Image: Alun Williams333 / Wikimedia Commons — Bohemian waxwing (Bombycilla garrulus) feeding on red hawthorn berries, photographed 8 December 2016. Representative species photograph, not a bird from the 33-year Tatarstan study. Cropped for the news-card format. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · 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

Bohemian Waxwing Bombycilla garrulus Explore species Eurasian Bullfinch Pyrrhula pyrrhula Explore species Redpoll Acanthis flammea Explore species

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