sciscape Publications

Linear hearing drift is not identified by bird survey turnover when observer cohort effects are free

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6 citing publications

We tested whether observer changes and song-frequency contrasts identify a linear hearing correction for bird climate tracking. We prove an exact equivalence between aging drift and observer cohort effects with a different calendar trend. We audit 130,303 standard Breeding Bird Survey runs on 5,319 routes in 1966-2025. Career and route tenure have no independent variation after observer-route and year effects. Aging and no-aging models give the same synthetic CTI means within 3.56e-15 C and the same turnover slope across 5,740 changes. Species-specific cohort effects can also preserve a song-frequency pattern. In a sensitivity model using rounded published slopes, an entry-cohort gradient of +0.005 CTI C per decade changes the corrected trend to zero. This is not an estimate of that gradient. The general age-period-cohort problem is established; the contribution is an explicit audit and sensitivity analysis of the thermal correction. The evidence supports a hearing mechanism but does not identify its linear correction without cohort restrictions or external detection data. We use schedule metadata and synthetic outcomes, not a new bird trend estimate.

climate tracking · observer effects · identifiability · hearing loss · age-period-cohort · community temperature index · Breeding Bird Survey
Quantitative MethodsPopulations and Evolution

References

8
  1. challengesLong-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)
  2. challengesBBS 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
  3. reviewsBird 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)
  4. reviewsCommunity 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)
  5. doi:10.5066/P144YU3S
  6. doi:10.1002/ece3.1101
  7. doi:10.1002/ecy.2545
  8. doi:10.1002/sim.7305

Cited by

6 publications
  1. 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%
  2. Paired bird surveys identify linear relative detection drift only when time varies within calibration cycles under free method intercepts uses
  3. Uniform count-scale changes had small mean effects on a bird thermal trend in 1997-2025 reviews
  4. A spatial thermal benchmark needs a 1.90-fold late-count allowance in log-weighted indices on 2,075 paired bird routes supports
  5. Controls kept a weighted spring shift estimate near 1.25 days per C in 317 North American bird species reviews
  6. Song frequency had no clear link to tenure curvature in 283 North American bird species in 1966-2025 uses, supports