BirdAnalyst
Species · Michigan · BBS 2026 Release · 1966–2025

Kirtland's Warbler Population Trend in Michigan

All statesForest birds

Kirtland's Warbler in Michigan has surged: up 341% on the route-weighted index since 2000.

+341%Since 2000TrendPercent 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 →
10Routes 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 →
27YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Kirtland's Warbler Trends in MichiganNotable 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 →

Kirtland's Warbler has surged in Michigan: up 341% on the route-weighted index since 2000.

Kirtland's Warbler Population Forecast in Michigan

If the recent trend holds, Kirtland's Warbler in Michigan is projected to fall about 39% by 2030 — from 0.32 in 2025 to a central estimate of 0.19 (95% range 0.09–0.30). A 5-year backtest shows a typical error of ±61.6%, with 20% of held-out values landing inside the 95% band.

-39%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 →
0.19Projected 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 →
0.09–0.3095% 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 →
±61.6%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, Kirtland's Warbler in Michigan is projected to fall about 39% by 2030 — from 0.32 in 2025 to a central estimate of 0.19 (95% range 0.09–0.30). A 5-year backtest shows a typical error of ±61.6%, with 20% of held-out values landing inside the 95% band.19862030
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 →
20260.170.070.28
20270.180.070.28
20280.180.080.29
20290.190.080.29
20300.190.090.30

Kirtland's Warbler Survey Routes in Michigan

Routes recording Kirtland's Warbler in Michigan.
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 →
Sand Lake1420252013
Red Oak520221986
Skeels320112000
Mayfield120142014
Hiawatha Nf120132013
Betchler Lks120162007
Ishpeming120102010
Scott'S Marsh120082008
Skegemog Pt120132002
Big Island Lake120092009

Kirtland's Warbler Population Trend in Other States

wisconsin

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