BirdAnalyst
Species · BCR 34 · BBS 2025 Release · 1966–2024

Northern Beardless-Tyrannulet In Sierra Madre Occidental

All regionsSierra Madre OccidentalAerial insectivores

Northern Beardless-Tyrannulet in Sierra Madre Occidental has fallen sharply: down 67% on the route-weighted index since 1971.

-67%Since 1971
6Routes In Region
49Years

Notable Signals

long arc declinecomputed index

Northern Beardless-Tyrannulet has fallen sharply in Sierra Madre Occidental: down 67% on the route-weighted index since 1971.

Forecast

If the recent trend holds, Northern Beardless-Tyrannulet in Sierra Madre Occidental is projected to fall about 49% by 2029 — from 0.28 in 2024 to a central estimate of 0.14 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±26.5%, with 100% of held-out values landing inside the 95% band.

-49%Change by 2029
0.14Projected 2029 index
0.00–0.4995% range
±26.5%Backtest error
19692029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.160.000.51
20260.150.000.51
20270.150.000.50
20280.150.000.50
20290.140.000.49

Routes In Sierra Madre Occidental

Routes recording Northern Beardless-Tyrannulet in Sierra Madre Occidental.
PomereneARIZONA32024
SahuaritaARIZONA32019
Peña BlancaARIZONA12024
PatagoniaARIZONA12024
RedingtonARIZONA12021
AmadoARIZONA12022

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.