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

Common Grackle Population Trend in Tennessee

All statesGeneralists

Common Grackle in Tennessee has collapsed: down 90% on the route-weighted index since 1968.

-90%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 →
54Routes 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 Common Grackle 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 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 →

Common Grackle has collapsed in Tennessee: down 89% on the route-weighted index since 1968.

Common Grackle Population Forecast in Tennessee

If the recent trend holds, Common Grackle in Tennessee is projected to fall about 100% by 2029 — from 6.7 in 2024 to a central estimate of 0.00 (95% range 0.00–21). A 5-year backtest shows a typical error of ±71.3%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–2195% 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 →
±71.3%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, Common Grackle in Tennessee is projected to fall about 100% by 2029 — from 6.7 in 2024 to a central estimate of 0.00 (95% range 0.00–21). A 5-year backtest shows a typical error of ±71.3%, with 100% 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 →
20250.670.0022
20260.000.0021
20270.000.0021
20280.000.0021
20290.000.0021

Common Grackle Survey Routes in Tennessee

Routes recording Common Grackle 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 →
Climer6720041967
Soddy5319811967
Red Bank4919781966
Pawpaw4420121966
Humboldt4020241966
Jefferson Cty3720111966
Tiptonville3420231966
Pawpaw 23420232013
Peytonsville3320241966
Wrigley3020221966
Bradyville2620211966
Mansfield1720241966
Collinwood1720241966
Campbellsville1720191966
Tullahoma1720151967
Jones Gap1720191982
Petersburg1620131966
Sweetlips1520061966
Belotes Bend1520181966
Lovell1520191966
Corryton Rd1520191966
Fish Springs1520231966
Walland1319891966
Indian Mound1219981966
Trace Collinwood1020152015

Common Grackle Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawest-virginiawisconsinwyoming

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