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q-bio.PE · Populations and Evolutionq-bio.QM · Quantitative Methods

Swedish bird lists showed weak support for spatial homogenization from 2000–2009 to 2016–2025 under survey controls

We tested whether recorded bird communities became more alike on Swedish fixed routes. We compared 2000–2009 with 2016–2025. We used the same 652 routes and drew three annual surveys per route and period, 200 times. Mean Sørensen dissimilarity fell from 0.46951 to 0.46315. The change was -0.00636, or a 1.35% decrease. A descriptive 95% interval from 100 km spatial blocks was -0.01262 to -0.00001. Its upper end was almost zero. With 200 km blocks, the interval was -0.01315 to +0.00096. Relative-count Bray–Curtis change was -0.00006 (-0.00666 to +0.00562). On the 97 routes with a long-term observer, species-list change was positive with all surveys (+0.00719) and with the same observer (+0.01057). Both intervals included zero. Thus the change of direction in this subset does not establish observer bias. This subset had a mean latitude of 59.15 degrees north, compared with 62.02 in the main set. Date matching and removal of chiffchaff also gave intervals that included zero. The evidence supports a small decrease in recorded list differences in the main sample. It does not give stable support for a general change across survey controls. Equal survey numbers do not correct for detection. The study does not test climate or land-use causes. The package preserves source bytes, provenance, code, all results, figures, and repeat instructions.

biodiversity · birds · Sweden · biotic homogenization · beta diversity · survey effort · observer effects · reproducibility

Admitted 2 citing publications

References

10
  1. usesdoi:10.15468/hd6w0r

    Swedish Bird Survey fixed routes, version 1.16; CC0 source counts and survey events.

  2. usesMean within-Sweden abundance centroids of 154 bird species did not move north with the isotherms in 1998–2025 fixed-route counts, with route and observer effects fixed sci:sha256:54019f16d5bb805257de1779f4f8df9d75e57693c3c95a623b049ce4a36fdc5f

    We reuse the raw v1.16 source archive that this study retained. Its analysis of coverage and observer effects also motivates survey controls. The same source data are not independent validation.

  3. Swedish bird community temperature index rose 0.06 °C per decade on 714 routes in 1996–2025, about half the long-term warming rate, but did not follow route warming rates or annual temperature sci:sha256:c84dfd7d5e48bd849b12a21d84ef26c02ce0b64d3d4de299884f282a9a9a2f66

    Related analysis of thermal community change using the same Swedish source data. It tests a different endpoint.

  4. doi:10.1111/gcb.16350

    Prior study of spatial homogenization across an urbanization gradient in Swedish woodlands.

  5. doi:10.1038/s41559-024-02326-7

    Prior evidence of community change and homogenization in British birds and other taxa.

  6. doi:10.1111/1365-2656.14145

    Prior analysis of British bird homogenization and species occurrence change. It motivates care with single community metrics.

  7. usesdoi:10.1111/j.1466-8238.2009.00490.x

    Source of the Simpson dissimilarity comparison.

  8. Recorded bird composition became more similar on 185 matched Swedish routes from 2000–2004 to 2021–2025 sci:sha256:16404dde9cc7eafa8324db7e915a77bfdcf0a9650203b08557b97d6ffe5c6805

    Contemporaneous same-source study found more similar recorded composition on 185 matched routes in narrower endpoint periods. We found this publication in the final catalog check. Our study uses 652 routes, wider periods, repeated survey rarefaction, and a different primary index. The estimates have different scopes.

  9. Observer changes were linked to higher annual bird community dissimilarity on Swedish fixed routes in 1996–2025 sci:sha256:7fb13ccc15da40ecce33026d77dd154e908f1112ab6848327b75e91a364674d1

    Contemporaneous same-source study linked observer changes to annual community dissimilarity. It motivates care with observer continuity, but it does not establish observer bias in our period comparison.

  10. doi:10.1111/1365-2656.12035

    Prior Swedish fixed-route study reported declining annual local beta diversity in 1998-2010 and tested temperature associations. Our pooled period comparison over 2000-2025 differs in scale and estimand and does not test its climate attribution.

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