BirdAnalyst
Species · BCR 35 · BBS 2025 Release · 1966–2024

Black-tailed Gnatcatcher In Chihuahuan Desert

All regionsChihuahuan DesertArid-land birds

Black-tailed Gnatcatcher in Chihuahuan Desert has fallen sharply: down 60% on the route-weighted index since 1969.

-60%Since 1969TrendPercent 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 →
37Routes 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 →
55YearsYears 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 Chihuahuan Desert: down 60% on the route-weighted index since 1969.

Black-tailed Gnatcatcher In Chihuahuan Desert Population Forecast

If the recent trend holds, Black-tailed Gnatcatcher in Chihuahuan Desert is projected to rise about 168% by 2029 — from 0.76 in 2024 to a central estimate of 2.0 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±93.6%, with 100% of held-out values landing inside the 95% band.

+168%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 →
2.0Projected 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 →
0.00–4.195% 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 →
±93.6%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 Chihuahuan Desert is projected to rise about 168% by 2029 — from 0.76 in 2024 to a central estimate of 2.0 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±93.6%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20252.00.004.0
20262.00.004.0
20272.00.004.1
20282.00.004.1
20292.00.004.1

Routes In Chihuahuan Desert

Routes recording Black-tailed Gnatcatcher in Chihuahuan Desert.
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 →
PresidioTEXAS132023
Quitman Cyn.TEXAS92009
Dove Mtn.TEXAS92006
LongfellowTEXAS52019
PumpvilleTEXAS42024
Red RockNEW-MEXICO32024
Hatchet PeakNEW-MEXICO32024
Black GapTEXAS32023
LangtryTEXAS32000
MesillaNEW-MEXICO22000
ColumbusNEW-MEXICO22024
GirvinTEXAS22017
Casa PiedraTEXAS22023
Devils R CynTEXAS22024
Sierra BlancTEXAS22024
MarfaTEXAS22022
GageNEW-MEXICO12024
JornadaNEW-MEXICO12023
RodeoNEW-MEXICO12022
Sunshine WllNEW-MEXICO12019
ComstockTEXAS12019
Hot SpringsTEXAS12024
ShafterTEXAS11985
AltudaTEXAS12010
Delaware CrkTEXAS12015

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