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Preliminary Climate Watch Results Suggest Western Bluebirds Are Shifting With Climate Suitability

Male western bluebird perched on a metal post at Point Pinole Regional Park, California
Research · Ecology

Preliminary results from ten years of Audubon’s Climate Watch suggest that western bluebirds (Sialia mexicana) are already changing where they occur as local climate suitability shifts. Audubon reported the result in June 2026 while its scientists were still analysing the full decade of data, so the finding should be read as an early result rather than a completed range-shift estimate.

Standardised point counts test climate-range projections

Climate Watch was launched in 2016 to test Audubon’s projections of climatically suitable bird ranges against repeated observations from the field. The programme began with 75 participants surveying bluebirds in four U.S. states and has grown to more than 1,000 participants annually across 12 target species.

Surveys are organised in fixed 10 × 10 km squares. Within each square, volunteers conduct 12 five-minute point counts from preselected locations, recording birds seen or heard within 100 metres. The same approach is repeated during a winter survey period and again during the breeding season. Recording both detections and non-detections allows researchers to compare observed occurrence with where climate models predict conditions should be suitable.

Western bluebirds appear relatively quick to follow suitable climate

Audubon says the expanded dataset provides stronger support for its climate-range projections than the programme’s earlier analysis, but species are not responding in the same way. Western bluebirds appear comparatively quick to occur in areas becoming climatically suitable.

Eastern bluebirds have been slower to shift their winter distribution, while several nuthatches appear more reluctant to occupy unfamiliar forests during the breeding season even where climatic conditions have become suitable. This contrast suggests that suitable climate alone does not determine whether a species can move into a new area; habitat and other ecological requirements can also limit range shifts.

The magnitude of the western-bluebird shift is not yet published

Audubon’s public 2026 report does not quantify how far western bluebird occurrence has shifted, how quickly the change happened or what proportion of the population is involved. The full decade-scale analysis was still underway when the result was announced.

The current evidence therefore supports a relationship between western-bluebird occurrence and changing climatic suitability, but not a precise estimate of the size or rate of the range shift. Audubon argues that comparing species that keep pace with changing climate against those that lag may help identify where habitat restoration, protected-area planning or improved opportunities for dispersal are most likely to matter.

Sources and image credit

  1. Audubon’s Climate Watch, Now a Decade Old, Has Tracked Shifts in Bird Ranges as Temperatures RiseOriginal 2026 public report of the preliminary decade-scale Climate Watch findings. Reports that Western Bluebirds appear to be relocating in line with changing climate suitability, while the full decade analysis is still in progress.
  2. Climate WatchOfficial Climate Watch programme page used for survey design and programme context.

Image: Male western bluebird at Point Pinole Regional Park, Richmond, California, 14 March 2015. Photo: Becky Matsubara / Wikimedia Commons. CC BY 2.0. Representative species image; not one of the birds recorded by Climate Watch. · 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

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