BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

Black-tailed Gnatcatcher In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsArid-land birds

Black-tailed Gnatcatcher in Sonoran and Mojave Deserts has fallen sharply: down 55% on the route-weighted index since 1970.

-55%Since 1970TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
66Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc declinecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Black-tailed Gnatcatcher has fallen sharply in Sonoran and Mojave Deserts: down 55% on the route-weighted index since 1970.

Black-tailed Gnatcatcher In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Black-tailed Gnatcatcher in Sonoran and Mojave Deserts is projected to rise about 134% by 2029 — from 2.2 in 2024 to a central estimate of 5.1 (95% range 0.86–9.3). A 5-year backtest shows a typical error of ±157.7%, with 80% of held-out values landing inside the 95% band.

+134%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
5.1Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.86–9.395% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±157.7%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Black-tailed Gnatcatcher in Sonoran and Mojave Deserts is projected to rise about 134% by 2029 — from 2.2 in 2024 to a central estimate of 5.1 (95% range 0.86–9.3). A 5-year backtest shows a typical error of ±157.7%, with 80% of held-out values landing inside the 95% band.19682029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20254.80.639.0
20264.90.699.1
20275.00.749.2
20285.00.809.2
20295.10.869.3

Routes In Sonoran and Mojave Deserts

Routes recording Black-tailed Gnatcatcher in Sonoran and Mojave Deserts.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Organ PipeARIZONA352023
New RiverARIZONA262016
Cibola LakeARIZONA242024
Bates WellARIZONA212023
Coachella CnCALIFORNIA192013
Cutter 2ARIZONA172018
Red RockARIZONA152014
GlamisCALIFORNIA152018
PisinimoARIZONA111993
Casa GrandeARIZONA102022
Cabeza PrietARIZONA92024
Alamo Res.ARIZONA82024
BlytheCALIFORNIA82003
AjoARIZONA72008
Havasu LakeCALIFORNIA72003
QuartzsiteARIZONA62024
WickenburgARIZONA62022
Willow BeachARIZONA61997
CoolidgeARIZONA41975
LukevilleARIZONA41981
Iron MtnsCALIFORNIA42018
Ash MeadowsNEVADA42006
OatmanARIZONA32019
LagunaARIZONA32023
AntaresARIZONA32018

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