BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Black-tailed Gnatcatcher

PolioptilidaeArid-land birdsPolioptila melanura

Black-tailed Gnatcatcher has declined: down 28% on the route-weighted index since 1969.

-28%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 →
144RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Black-tailed Gnatcatcher

The Black-tailed Gnatcatcher (Polioptila melanura) is a North American member of the Gnatcatchers (Polioptilidae). In this analysis it is grouped with the arid-land birds.

Size
4–5 in long (10–13 cm) — a tiny, long-tailed songbird (typical for the family)
Habitat
Deserts, dry scrub and brushland of the Southwest.
Diet
Seeds, insects and cactus fruit of arid-land plants.
Range
Recorded on 144 Breeding Bird Survey routes across 6 states, most concentrated in the Sonoran and Mojave Deserts.
Family
Polioptilidae · Arid-land birds

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

No notable trend signals for Black-tailed Gnatcatcher. See the full index history below.

Black-tailed Gnatcatcher Population Forecast

If the recent trend holds, Black-tailed Gnatcatcher is projected to stay roughly flat through 2029, near 0.13 (95% range 0.05–0.21). A 5-year backtest shows a typical error of ±166.4%, with 20% of held-out values landing inside the 95% band.

n/aChange 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 →
0.13Projected 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 →
0.05–0.2195% 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 →
±166.4%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 is projected to stay roughly flat through 2029, near 0.13 (95% range 0.05–0.21). A 5-year backtest shows a typical error of ±166.4%, with 20% 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 →
20250.130.050.21
20260.130.050.21
20270.130.050.21
20280.130.050.21
20290.130.050.21

Where the Black-tailed Gnatcatcher Is Detected

BBS routes recording Black-tailed Gnatcatcher, sized by most recent count.

Black-tailed Gnatcatcher Population Trend by State

Black-tailed Gnatcatcher population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Arizona-52%197052
California-74%197133
Nevada-74%19738
New Mexico+215%19959
Texas-44%196941
Utahinsufficient datan/a1

Black-tailed Gnatcatcher Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Black-tailed Gnatcatcher population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Sonoran and Mojave Deserts-55%197066
Sierra Madre Occidental-18%197116
Chihuahuan Desert-60%196937
Tamaulipan Brushlands+105%19939

Black-tailed Gnatcatcher Conservation Status

Our route-weighted index shows it down about 28% since 1969.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.