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

Purple Finch Population Trend in Maryland

All statesGeneralists

Purple Finch in Maryland has surged: up 412% on the route-weighted index since 1977.

+412%Since 1977TrendPercent 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 →
8Routes 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 →
41YearsYears 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 Finch Trends in MarylandNotable 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 Finch has surged in Maryland: up 412% on the route-weighted index since 1977.

Purple Finch Population Forecast in Maryland

If the recent trend holds, Purple Finch in Maryland is projected to stay roughly flat through 2029, near 0.09 (95% range 0.02–0.16). A 5-year backtest shows a typical error of ±114.6%, with 60% 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 →
0.09Projected 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 →
0.02–0.1695% 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 →
±114.6%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 Finch in Maryland is projected to stay roughly flat through 2029, near 0.09 (95% range 0.02–0.16). A 5-year backtest shows a typical error of ±114.6%, with 60% of held-out values landing inside the 95% band.19722029
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 →
20250.090.020.15
20260.090.020.15
20270.090.020.16
20280.090.020.16
20290.090.020.16

Purple Finch Survey Routes in Maryland

Routes recording Purple Finch in Maryland.
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 →
Finzel420231996
Floyd120161972
Mt Nebo119901983
Vindex120221979
Potomac Park119851985
Accident120161995
Jennings120231995
Steyer120242006

Purple Finch Population Trend in Other States

alaskacaliforniaconnecticutindianamainemassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-dakotaohiooregonpennsylvaniarhode-islandvermontwashingtonwest-virginiawisconsin

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