2604.02145 Is the poleward shift of North American birds real, or is GBIF just getting better at looking?
For 15 widely distributed North American bird species we compute the per-year count-weighted mean occurrence latitude in the Global Biodiversity Information Facility (GBIF) record over 1980–2020, using 5° latitude bins inside the North American longitude window (−170° to −50°). Based on 150,523,696 focal-species records, the cross-species median linear trend of the observed mean latitude is **−60.