BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Cave Swallow

HirundinidaeAerial insectivoresPetrochelidon fulva

Cave Swallow has surged: up 550% on the route-weighted index since 1980.

+550%Since 1980TrendPercent 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 →
155RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
46Years 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 Cave Swallow

The Cave Swallow (Petrochelidon fulva) is a North American member of the Swallows & Martins (Hirundinidae). In this analysis it is grouped with the aerial insectivores.

Size
4.5–8 in long (12–20 cm) — a small, streamlined bird (typical for the family)
Habitat
Open airspace over fields, water and towns; nests in cavities, earthen banks or on structures.
Diet
Flying insects caught on the wing.
Range
Recorded on 155 Breeding Bird Survey routes across 4 states, most concentrated in the Oaks and Prairies.
Family
Hirundinidae · Aerial insectivores

Notable Cave Swallow 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 Cave Swallow. See the full index history below.

Cave Swallow Population Forecast

If the recent trend holds, Cave Swallow is projected to rise about 74% by 2029 — from 0.33 in 2024 to a central estimate of 0.56 (95% range 0.27–0.86). A 5-year backtest shows a typical error of ±190%, with 0% of held-out values landing inside the 95% band.

+74%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 →
0.56Projected 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 →
0.27–0.8695% 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 →
±190%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, Cave Swallow is projected to rise about 74% by 2029 — from 0.33 in 2024 to a central estimate of 0.56 (95% range 0.27–0.86). A 5-year backtest shows a typical error of ±190%, with 0% of held-out values landing inside the 95% band.19712029
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 →
20250.540.240.83
20260.550.250.84
20270.550.260.85
20280.560.260.85
20290.560.270.86

Where the Cave Swallow Is Detected

BBS routes recording Cave Swallow, sized by most recent count.

Cave Swallow Population Trend by State

Cave Swallow 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 →
Louisiana21×201315
New Mexicoinsufficient datan/a2
Oklahomainsufficient datan/a1
Texas+410%1980137

Cave Swallow Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Cave Swallow 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 →
Shortgrass Prairie+85%20086
Central Mixed Grass Prairie-35%199410
Edwards Plateau+247%198417
Oaks and Prairies-54%198635
Chihuahuan Desert+70%198420
Tamaulipan Brushlands+2%198225
Gulf Coastal Prairie+43%199630

Cave Swallow Conservation Status

Our route-weighted index shows it up about 550% since 1980. Aerial insectivores have fallen sharply across the continent, a decline widely linked to dwindling insect prey.

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