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Species · Michigan · BBS 2025 Release · 1966–2024

Kirtland's Warbler Population Trend in Michigan

All statesForest birds

Kirtland's Warbler in Michigan has surged: up 269% on the route-weighted index since 2000.

+269%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 →
26YearsYears 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 269% 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 stay roughly flat through 2029, near 0.16 (95% range 0.08–0.25). A 5-year backtest shows a typical error of ±56.9%, with 60% of held-out values landing inside the 95% band.

+9%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 →
0.16Projected 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 →
0.08–0.2595% 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 →
±56.9%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 stay roughly flat through 2029, near 0.16 (95% range 0.08–0.25). A 5-year backtest shows a typical error of ±56.9%, with 60% of held-out values landing inside the 95% band.19862029
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 →
20250.150.060.23
20260.150.070.23
20270.150.070.24
20280.160.070.24
20290.160.080.25

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 Lake720242013
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 2026-05-22.