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

Loggerhead Shrike Population Trend in Iowa

All statesGeneralists

Loggerhead Shrike in Iowa has collapsed: down 86% on the route-weighted index since 1969.

-86%Since 1969TrendPercent 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 →
34Routes 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Loggerhead Shrike Trends in IowaNotable 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 →

Loggerhead Shrike has collapsed in Iowa: down 86% on the route-weighted index since 1969.

Loggerhead Shrike Population Forecast in Iowa

If the recent trend holds, Loggerhead Shrike in Iowa is projected to stay roughly flat through 2027, near 0.00 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±94.2%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2027TrendPercent 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 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.4995% 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 →
±94.2%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, Loggerhead Shrike in Iowa is projected to stay roughly flat through 2027, near 0.00 (95% range 0.00–0.49). A 5-year backtest shows a typical error of ±94.2%, with 100% of held-out values landing inside the 95% band.19672027
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 →
20230.010.000.50
20240.000.000.49
20250.000.000.49
20260.000.000.49
20270.000.000.49

Loggerhead Shrike Survey Routes in Iowa

Routes recording Loggerhead Shrike in Iowa.
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 →
Panther419941971
Rock Valley419821982
College Spgs320041967
Pierson320031968
Bedford220101968
Bryant219941994
Wales220131967
Hudson219921969
Zearing219941968
Scranton219971983
Davis Corner219941994
Garner219891989
Mccallsburg220121997
Mt Hamill120051970
Exline120091974
Melrose120111976
West Liberty119941970
Burchinal119951995
Brooklyn120071969
Williamsburg120171967
Red Rock120051969
Desmoines119721968
Washington119931967
Neola120061968
Maquoketa120042004

Loggerhead Shrike Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradofloridageorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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