BirdAnalyst
Species · BCR 34 · BBS 2026 Release · 1966–2025

Violet-green Swallow In Sierra Madre Occidental

All regionsSierra Madre OccidentalAerial insectivores

Violet-green Swallow in Sierra Madre Occidental has risen sharply: up 54% on the route-weighted index since 1970.

+54%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 →
33Routes 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 increasecomputed 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 →

Violet-green Swallow has risen sharply in Sierra Madre Occidental: up 54% on the route-weighted index since 1970.

Violet-green Swallow In Sierra Madre Occidental Population Forecast

If the recent trend holds, Violet-green Swallow in Sierra Madre Occidental is projected to fall about 45% by 2030 — from 13 in 2025 to a central estimate of 6.9 (95% range 2.1–12). A 5-year backtest shows a typical error of ±20.5%, with 80% of held-out values landing inside the 95% band.

-45%Change by 2030TrendPercent 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 →
6.9Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
2.1–1295% 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 →
±20.5%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, Violet-green Swallow in Sierra Madre Occidental is projected to fall about 45% by 2030 — from 13 in 2025 to a central estimate of 6.9 (95% range 2.1–12). A 5-year backtest shows a typical error of ±20.5%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20267.02.112
20276.92.112
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20306.92.112

Routes In Sierra Madre Occidental

Routes recording Violet-green Swallow in Sierra Madre Occidental.
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 →
Happy JackARIZONA972025
AlpineARIZONA762025
SprucedaleARIZONA372025
WilliamsARIZONA362025
RuckerARIZONA272001
BlueARIZONA251991
PinetopARIZONA252022
Aztec PeakARIZONA231978
Tonto Vill.ARIZONA172025
Forest LakesARIZONA142025
Mormon LakeARIZONA131975
PrescottARIZONA122025
FlagstaffARIZONA112025
MaineARIZONA102025
Mt. GrahamARIZONA102025
San SimonARIZONA61982
SunizonaARIZONA61996
Clay SpringARIZONA52009
ReserveNEW-MEXICO52025
Emory PassNEW-MEXICO52025
Bartlett ResARIZONA42025
Carr MtnARIZONA42025
Peña BlancaARIZONA32021
RedingtonARIZONA32021
Skull Valley 2ARIZONA22025

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.