BirdAnalyst
Species · BCR 18 · BBS 2025 Release · 1966–2024

Northern Harrier In Shortgrass Prairie

All regionsShortgrass PrairieGeneralists

Northern Harrier in Shortgrass Prairie has collapsed: down 76% on the route-weighted index since 1969.

-76%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 →
109Routes 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 →
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 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 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 →

Northern Harrier has collapsed in Shortgrass Prairie: down 76% on the route-weighted index since 1969.

Northern Harrier In Shortgrass Prairie Population Forecast

If the recent trend holds, Northern Harrier in Shortgrass Prairie is projected to stay roughly flat through 2029, near 0.23 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±32.9%, with 100% of held-out values landing inside the 95% band.

-6%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 →
0.23Projected 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 →
0.00–0.7395% 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 →
±32.9%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, Northern Harrier in Shortgrass Prairie is projected to stay roughly flat through 2029, near 0.23 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±32.9%, 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 →
20250.260.000.76
20260.250.000.76
20270.240.000.75
20280.230.000.74
20290.230.000.73

Routes In Shortgrass Prairie

Routes recording Northern Harrier in Shortgrass Prairie.
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 →
PlainsTEXAS101993
Adams Co.COLORADO52021
Agate 2NEBRASKA42024
GruverTEXAS42016
BriggsdaleCOLORADO32021
GilpinCOLORADO32011
WaverlyCOLORADO32019
CheyenneCOLORADO32018
Last Chance 2COLORADO32024
Prospect ValCOLORADO32000
Prospect Valley 2COLORADO32022
PaxtonNEBRASKA32016
KimballNEBRASKA32021
MarslandNEBRASKA32021
PinneoCOLORADO22018
AbarrCOLORADO21999
Two ButtesCOLORADO22009
Wildhorse LCOLORADO22024
Gordon CreekCOLORADO22022
KirkCOLORADO22023
NinaviewCOLORADO22004
TimpasCOLORADO22006
WallaceKANSAS22017
RuletonKANSAS22014
PlymellKANSAS22011

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