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Climate suitability change predicted little of US bird abundance change in 2010-2025: 0.05 per log unit within species on survey routes, and no species-level forecast skill

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9 citing publications

Stephens et al. (2016) reported that climate suitability trends predict bird population trends. We tested this forward in time with the US Breeding Bird Survey (2026 release, 1966-2025) and nClimGrid monthly climate. We fitted one Poisson climate model for each of 367 species to its 1981-2000 distribution on 2,690 routes (346 species with spatial-block AUC 0.7 or more) and kept the models frozen. We compared suitability change with abundance change in 1981-2009 and in a forward period 2010-2025, in the East and the West, with observer controls. Within species, abundance change between 2010-14 and 2021-25 followed suitability change on 1,623 routes: 0.053 log units per log unit (95% CI 0.035 to 0.070), East 0.061, West 0.036. The result stayed positive with species x region fixed effects, same-observer routes, a boosted-tree model and US-centred species, and it followed 2010-2025 suitability change, not 1981-2009 change. In 1981-2009 the within-species link was weaker and not robust. Between species, suitability trends did not predict population trends in 1981-2009 (Spearman -0.01) and only weakly in 2010-2025 (0.085, p = 0.11); a model calibrated on 1981-2009 had no forecast skill for 2010-2025. Species suitability trends were not stable between periods (Spearman 0.03). Observer fixed effects made the median 2010-2025 trend more negative (-0.134 versus -0.050 log per decade). Limitations: US-only climate models cut cross-border ranges, the models have four climate variables and no land cover, suitability errors reduce the coefficient, and BBS counts do not model detection.

Breeding Bird Survey · climate suitability · species distribution model · climate impact indicator · forward test · population trend · observer bias · nClimGrid · climate change · birds · range dynamics · United States
Ecological impacts of climate change and ecological adaptationPopulation ecologyPopulations and Evolution

References

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  1. reviews, challengesdoi:10.1126/science.aac4858
  2. usesdoi:10.5066/P144YU3S
  3. usesdoi:10.7289/V5SX6B56
  4. supportsBird community temperature index followed less than 10% of May-July warming on 5,294 North American survey routes in 1970-2024 with route and observer controls
  5. Drought lowered bird counts in the dry central US plains again in 2006-2025, about 7-9% at SPI -3 (10.7% published); ten rain-tracking species gave half and the montane response did not repeat
  6. Finnish atlas range margins of southern birds moved north more slowly in 2006-10 to 2022-25 than before while isotherms moved fast; lower detection in 2022-25 explains part of this

Cited by

9 publications
  1. Community thermal composition in 75 monitoring networks followed about 12% of its own spatial temperature gradient in time; a lag fit gives fast adjustment to a small target (1948-2025) supports
  2. Forest type explained about half of the gap between spatial and temporal bird community temperature slopes on 2,523 forested US routes (1966-2025), but not in open-habitat birds, the East, or species
  3. Passing vehicles hid low-pitched, warm-adapted birds at North American Breeding Bird Survey stops in 1997-2025, but traffic grew too little to change the bird temperature index trend by over 1%
  4. Warm springs act like a 1.5-day later survey per 1 C in Breeding Bird Survey counts of 317 species (1966-2025); this phenology-detection artefact is real but too small to explain weak climate tracking
  5. Year-to-year temperature responses of 320 North American bird species followed 5-14% of own spatial gradients, with no clear lasting part; 49 British butterfly species followed about 50% in 2 summers supports
  6. Bird abundance gradients between nearby US survey routes kept 69% of the regional temperature gradient per degree with 5 km route-path climate; year-to-year tracking stayed at about 3% (1966-2025)
  7. Long-serving Breeding Bird Survey observers recorded fewer high-pitched birds; because cold-adapted species sing higher, this drift made 31-77% of the within-observer CTI warming trend (1966-2025)
  8. US breeding bird communities sort by temperature almost as strongly between nearby routes as across the continent, but in time they follow only 3-24% of this slope (BBS 1966-2025) supports
  9. BBS observers recorded about 41% fewer birds that sing at 7 kHz or more after 20 years on a route; route x observer models put this loss into 1966-2025 trends of 446 species