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

Loggerhead Shrike Population Trend in Louisiana

All statesGeneralists

Loggerhead Shrike in Louisiana has collapsed: down 82% on the route-weighted index since 1969.

-82%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 →
89Routes 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 →
57YearsYears 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 LouisianaNotable 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 Louisiana: down 82% on the route-weighted index since 1969.

Loggerhead Shrike Population Forecast in Louisiana

If the recent trend holds, Loggerhead Shrike in Louisiana is projected to rise about 33% by 2029 — from 1.0 in 2024 to a central estimate of 1.3 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±145.8%, with 100% of held-out values landing inside the 95% band.

+33%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 →
1.3Projected 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 →
0.00–3.795% 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 →
±145.8%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 Louisiana is projected to rise about 33% by 2029 — from 1.0 in 2024 to a central estimate of 1.3 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±145.8%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20251.60.004.0
20261.60.003.9
20271.50.003.8
20281.40.003.8
20291.30.003.7

Loggerhead Shrike Survey Routes in Louisiana

Routes recording Loggerhead Shrike in Louisiana.
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 →
Creole2719871967
Carlisle2219881968
Mamou1919821967
Junior1119911987
Lafitte919911967
Brousville920241998
Ltl Chenier 2920112010
Larose819921988
Morgan City719861967
Frogmore620241998
Grand Isle620192010
Burr Ferry620041987
Delhi620212011
Gran Chenier519811967
Keystone520131967
Mer Rouge520081969
Fillmore519891968
Berwick520181987
Cypress419871967
Fort Polk419751967
Transylvania420221998
Concord420192006
Morgan City420222011
Hackberry320141967
De Ridder320191967

Loggerhead Shrike Population Trend in Other States

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

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