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

Franklin's Gull In Northern Rockies

All regionsNorthern RockiesWetland birds

Franklin's Gull in Northern Rockies has surged: up 279% on the route-weighted index since 1974.

+279%Since 1974TrendPercent 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 →
21Routes 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 →
40YearsYears 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 →

Franklin's Gull has surged in Northern Rockies: up 279% on the route-weighted index since 1974.

Franklin's Gull In Northern Rockies Population Forecast

If the recent trend holds, Franklin's Gull in Northern Rockies is projected to stay roughly flat through 2029, near 1.8 (95% range 0.00–11). A 5-year backtest shows a typical error of ±3345.6%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
1.8Projected 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 →
0.00–1195% 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 →
±3345.6%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, Franklin's Gull in Northern Rockies is projected to stay roughly flat through 2029, near 1.8 (95% range 0.00–11). A 5-year backtest shows a typical error of ±3345.6%, with 80% of held-out values landing inside the 95% band.19702029
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 →
20251.90.0011
20261.90.0011
20271.90.0011
20281.90.0011
20291.80.0011

Routes In Northern Rockies

Routes recording Franklin's Gull 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 →
Rock RiverWYOMING1291998
LimaMONTANA572004
WilsonWYOMING411994
Saleratus CrUTAH392007
BoulderMONTANA301993
Wolf CreekMONTANA152018
AugustaMONTANA32012
GreenoughMONTANA32003
YellowstoneWYOMING31987
FeathervilleIDAHO22013
BeaverheadMONTANA22015
Red RockMONTANA22024
Crawford MtsUTAH22002
FontenelleWYOMING22022
St MaryMONTANA11974
RandolphUTAH12021
Neponset ResUTAH12003
WoodruffUTAH12024
CodyWYOMING12001
ClarkWYOMING12000
AlpineWYOMING12016

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