BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Lark Sparrow In Northern Rockies

All regionsNorthern RockiesGrassland birds

Lark Sparrow in Northern Rockies has risen sharply: up 61% on the route-weighted index since 1970.

+61%Since 1970TrendPercent 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 →
126Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Lark Sparrow has risen sharply in Northern Rockies: up 61% on the route-weighted index since 1970.

Lark Sparrow In Northern Rockies Population Forecast

If the recent trend holds, Lark Sparrow in Northern Rockies is projected to fall about 24% by 2029 — from 2.1 in 2024 to a central estimate of 1.6 (95% range 0.70–2.4). A 5-year backtest shows a typical error of ±18.8%, with 100% of held-out values landing inside the 95% band.

-24%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 →
1.6Projected 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 →
0.70–2.495% 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 →
±18.8%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, Lark Sparrow in Northern Rockies is projected to fall about 24% by 2029 — from 2.1 in 2024 to a central estimate of 1.6 (95% range 0.70–2.4). A 5-year backtest shows a typical error of ±18.8%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20251.50.662.4
20261.50.672.4
20271.60.682.4
20281.60.692.4
20291.60.702.4

Routes In Northern Rockies

Routes recording Lark Sparrow in Northern Rockies.
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 →
LysiteWYOMING472024
TensleepWYOMING322024
LaurelMONTANA232022
GeboWYOMING232024
Muddy CreekMONTANA182015
Browns ParkCOLORADO152024
BasinWYOMING142024
MadrasOREGON122024
NowoodWYOMING112024
LovellWYOMING112024
WorlandWYOMING112024
TwickenhamOREGON102024
WamsutterWYOMING101995
Patrick Draw 4WYOMING92002
MaybellCOLORADO72024
OttoWYOMING72024
DuboisWYOMING72024
CrowheartWYOMING72021
PathfinderWYOMING72024
CascadeIDAHO61983
Crane CreekIDAHO62019
EtheteWYOMING62024
SweetwaterWYOMING62017
HarmonyWYOMING62008
LayCOLORADO52024

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