BirdAnalyst
Species · Tennessee · BBS 2025 Release · 1966–2024

Purple Martin Population Trend in Tennessee

All statesAerial insectivores

Purple Martin in Tennessee has risen sharply: up 50% on the route-weighted index since 1968.

+50%Since 1968TrendPercent 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 →
52Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Purple Martin Trends in TennesseeNotable 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 →

Purple Martin has risen sharply in Tennessee: up 50% on the route-weighted index since 1968.

Purple Martin Population Forecast in Tennessee

If the recent trend holds, Purple Martin in Tennessee is projected to fall about 39% by 2029 — from 12 in 2024 to a central estimate of 7.4 (95% range 3.4–11). A 5-year backtest shows a typical error of ±55.4%, with 60% of held-out values landing inside the 95% band.

-39%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 →
7.4Projected 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 →
3.4–1195% 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 →
±55.4%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, Purple Martin in Tennessee is projected to fall about 39% by 2029 — from 12 in 2024 to a central estimate of 7.4 (95% range 3.4–11). A 5-year backtest shows a typical error of ±55.4%, with 60% of held-out values landing inside the 95% band.19662029
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 →
20257.23.211
20267.33.211
20277.33.311
20287.33.311
20297.43.411

Purple Martin Survey Routes in Tennessee

Routes recording Purple Martin in Tennessee.
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 →
Peytonsville5120241966
Pawpaw 24920232013
Mansfield4620241966
Signal Mtn4220241979
Glen3620241966
Humboldt3220241966
Walland2519871966
Lovell2020191966
Tiptonville1920231966
Tullahoma1620151967
Big Sandy1320241966
Jefferson Cty1320111966
Pawpaw1120121967
Collinwood1120241968
Red Bank1119781966
Union Hill1020241967
Jones Gap820191982
Whiteville720241966
Corryton Rd720191966
Silerton620241967
Wrigley620221968
Moscow520231968
Bradyville520151970
Jasper520241967
Trace Collinwood520182015

Purple Martin Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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